Valve Seat Issues?

[richbiker]

Antone else seen M8 Valve seats bad?

https://www.facebook.com/100157792180/videos/10154969685867181/

[rbabos]

Oh great.
Ron

[BVHOG]

Just saw that today, with the diminishing quality of the MoCo I am not even a little surprised.

[No Cents]

  they are going to be lined up at the dealerships now for leak down tests to be done after TR posted that video. 
Those M8's still scare me.

[1FSTRK]

 
Great job by TR getting the word out, very well done video with good information including what percentage of problem heads and honest sample size.

[HV]

MOCO says normal Leak dome is up to 13% 

[BVHOG]

You don't suppose lean mixture, late ignition timing and excessive heat has anything to do with this do you?

[1FSTRK]

TR indicated it was a machining problem.
There did not appear to be any high heat signs on the heads in the video.

[FSG]

1 bad replace all 4  ,   

[Durwood]

  they are going to be lined up at the dealerships now for leak down tests to be done after TR posted that video. 
Those M8's still scare me.

I recently tested mine and it was less than 1% on both cylinders, I guess my bike was built in the middle of the week.

You don't suppose lean mixture, late ignition timing and excessive heat has anything to do with this do you?

Definite possibility Bob..My shop bike had one mile on it when I put it on the dyno for the initial break in and tune.

Oh great.
Ron

Come on Ron, tell us how you really feel.

[Durwood]

I just chatted with Wes Brown and he hasn't seen any loose seats yet.

[1FSTRK]

I just chatted with Wes Brown and he hasn't seen any loose seats yet.

I think one point of the video is, is anyone else checking? It does appear that they could get past a visual check.

[prodrag1320]

You don't suppose lean mixture, late ignition timing and excessive heat has anything to do with this do you?

on a properly installed seat,none of this would result in a seat coming loose.i havnt seen any loose seats yet,but I really havnt been looking for one either

[badcooky]

The video looked seriously bogus .

[Herko]

MOCO says normal Leak dome is up to 13% 

Wow.

[rbabos]

  they are going to be lined up at the dealerships now for leak down tests to be done after TR posted that video. 
Those M8's still scare me.

I recently tested mine and it was less than 1% on both cylinders, I guess my bike was built in the middle of the week.

You don't suppose lean mixture, late ignition timing and excessive heat has anything to do with this do you?

Definite possibility Bob..My shop bike had one mile on it when I put it on the dyno for the initial break in and tune.

Oh great.
Ron

Come on Ron, tell us how you really feel.

Well, I do like the whole M8 thing and was considering one for a while. Problem is, the quality issues just keep coming. Issues that should not be there in the first place and if any are there, they should be looked after, not specs provided to justify the problem rather then resolve the issues. That burns my ass to no end.  My V rod may very well be the last HD I own. If they could get the M8 to the reliability state of the Revolution drive train MoCo could have the world by the ass. With the current mind set of the company it looks they are heading the other direction. Who in their right gear head mind could accept loose valve seats and be told 13% leak down is acceptable for the cost of these things? Not me.
Ron

[Buglet]

   Durwood
                  What pressure did you use to check the leak down, did you check it at BDC, TDC, and in the middle. Thanks.     

[koko3052]

Cost keeps going up....quality keeps going down.

[FSG]

The video looked seriously bogus .

Are you serious ?

[Ohio HD]

The video looked seriously bogus .

Having met Tom on two occasions at the Ohio Mile, talking Twin Cams and Sportsters (he was racing a Sportster there), he's a super knowledgeable guy, very pleasant, and also listens to you. I believe he wouldn't put something in public view if he had not seen this as an issue. Not to mention his reputation as being a straight up shop owner.

[HV]

MOCO says normal Leak dome is up to 13% 

Wow.

To be honest they say close to 20% is nothing to worry about ....Id have to disagree with that ....but I havent seen any close to that yet ....I guess High Mileage will tell the story FYI a Dealer is not going to replace seats ....just complete heads

[wfolarry]

I remember the Evo Sprtsters having the same issue. Standard test was to slam them on a piece of wood & see if the seats fall out. Wasn't a major problem but it was something you checked when you had one that was running bad & you ruled out everything else before you took it apart. If it is a problem [this is the first I heard of it] the MOCO will just increase the press fit & keep right on building bikes.
I do think what Durwood said makes a difference. Good tune always helps & never hurts. 
Most of the failures I seen were heat related. With water cooling & oil cooling I don't see it becoming a major problem.

[Durwood]

   Durwood
                  What pressure did you use to check the leak down, did you check it at BDC, TDC, and in the middle. Thanks.   

I checked it at the bottom and top, not the middle.

[04 SE Deuce]

   Maybe they can pressurize the primary with some of the blow-by so the trans lube will stay in the trans.

Makes me laugh when people state Harley quality is going down...they use to make some real junk.  Harley has always had an absurd amount of difficulty with design changes compared to Japanese bikes.  The M8 will be fine once sorted.

[rbabos]

  Maybe they can pressurize the primary with some of the blow-by so the trans lube will stay in the trans.

Makes me laugh when people state Harley quality is going down...they use to make some real junk.  Harley has always had an absurd amount of difficulty with design changes compared to Japanese bikes. The M8 will be fine once sorted.

Sure it will be sorted. In the mean time, I'll let others make donations to their bottom line while they take their sweet ass time solving issues and get it where it should have been in the first place. It was mentioned he EVO Sportsters had this issue at first. Does this company ever learn from their mistakes?
Ron

[flh canuck]

Wonder if this issue applies to both oil cooled and liquid cooled heads and what production dates?

[Ancient]

Yep, that's ugly. 

[harleytuner]

The video looked seriously bogus .

Having met Tom on two occasions at the Ohio Mile, talking Twin Cams and Sportsters (he was racing a Sportster there), he's a super knowledgeable guy, very pleasant, and also listens to you. I believe he wouldn't put something in public view if he had not seen this as an issue. Not to mention his reputation as being a straight up shop owner.

Tom is a straight up dude.  I can't seeing him making a bogus video. 

[PoorUB]

Well, I do like the whole M8 thing and was considering one for a while. Problem is, the quality issues just keep coming. Issues that should not be there in the first place and if any are there, they should be looked after, not specs provided to justify the problem rather then resolve the issues. That burns my ass to no end.  My V rod may very well be the last HD I own. If they could get the M8 to the reliability state of the Revolution drive train MoCo could have the world by the ass. With the current mind set of the company it looks they are heading the other direction. Who in their right gear head mind could accept loose valve seats and be told 13% leak down is acceptable for the cost of these things? Not me.
Ron

I was seriously hoping the M8 would be something new and great when news of it first came out. As far as I am concerned it is just a variation of a Twin Cam with new issues to deal with. I think they would have been better off to move out the cylinder studs on the TC and slap larger bore cylinders on it and keep running it that deal with the mes mess they started.

I rode imports all my life and finally bought my first HD in 2005, on my third one and growing tired of it all. For the money these bikes cost the technology and quality is lacking.

A BMW or even the new 2018 Gold Wing looks interesting.

[Tattoo]

The video looked seriously bogus .

I have been doing business with T-Man Performance for many years and TR and his crew are pretty straight up.

[CarlosGGodfrog]

Unless the replacement seats have a larger OD, how does a CNC machine make a hole smaller to get a tighter press fit ? Back in the fifties, weren't screw-in seats available for cars ?

[Don D]

Use a larger seat
TR is straight up.

[CarlosGGodfrog]

Ok, that makes sense.

[gonenorth]

  Maybe they can pressurize the primary with some of the blow-by so the trans lube will stay in the trans.

Makes me laugh when people state Harley quality is going down...they use to make some real junk.  Harley has always had an absurd amount of difficulty with design changes compared to Japanese bikes.  The M8 will be fine once sorted.

[Don D]

A detail not often discussed HD uses different vendors for castings and even within a single vendor there are different alloys. The numbers on the heads like 332, 332M, and 242 t5, all designate the alloy and heat or process treatment.  A poorly heat treated head could have a seat in at the proper press fit and still drop later. Once it is moving no telling what the original fit was.

[Ancient]

Question Don, or anyone else that might know, does the moco just buy in blank castings and machine and assemble themselves, or do they buy them in completely assembled and ready for install?

[Don D]

I don't know for sure but I would guess the part comes from the vendor completed and ready to install even if they have to subcontract some of the parts like the main casting. Typically in automotive the casting and all the component parts have individual numbers, many of which are not published and used on the build of materials internally to comprise the whole assembly which is the finished part number available to the public. Then all the individual parts such as springs valves and the other repair parts are also cataloged.

[TorQuePimp]

  would be far more valid for those of us that know

to provide interference fit numbers

If you are replacing them all....welding or cutting them out pretty easy to measure one and see

by the looks of it the press fit is less than .006 the three ive removed

[tmwmoose]

A detail not often discussed HD uses different vendors for castings and even within a single vendor there are different alloys. The numbers on the heads like 332, 332M, and 242 t5, all designate the alloy and heat or process treatment.  A poorly heat treated head could have a seat in at the proper press fit and still drop later. Once it is moving no telling what the original fit was.

That reminds me of a laugh years ago when I would attend factory school. When ever the factory would discuss a problem going on and what they found to fix it always started off with .."Well the VENDOR that made the gear that's failing blah blah blah told us blah blah ."

[rbabos]

  would be far more valid for those of us that know

to provide interference fit numbers

If you are replacing them all....welding or cutting them out pretty easy to measure one and see

by the looks of it the press fit is less than .006 the three ive removed

.006 is pretty tight.
Ron

[Moparnut72]

With.006 interference fit I don't see how you could get the guides in no matter how much heat and liquid nitrogen or dry ice is used.
kk

[Don D]

.006 is a little light on a seat
Guides a new story.

[rbabos]

.006 is a little light on a seat
Guides a new story.

What would you feel as a save interference with seats being so close to each other and available aluminum mass before they crack? Just curious.
Ron

[Moparnut72]

Yeah, you are right. I was thinking guides.    On the radials I worked on if the seats were bad the cylinder was then junk.
kk

[Don D]

Ron
.007 with a seat that size all things considered especially considering the heat some of these motors are subjected to.

[rbabos]

Ron
.007 with a seat that size all things considered especially considering the heat some of these motors are subjected to.

Thanks.
Ron

[jsachs1]

Ron
.007 with a seat that size all things considered especially considering the heat some of these motors are subjected to.

[prodrag1320]

Yeah, you are right. I was thinking guides.    On the radials I worked on if the seats were bad the cylinder was then junk.
kk

ive got a set of S&S heads a local shop installed a .008 guide in a STD hole,needless to say,it cracked all the way thru the head.we install seats @ .008 & guides @ .002.heat/freeze on both to install.a properly installed seat should never move or come out

[Don D]

Ok but then the alloy and heat treat (or lack of) needs to be factored.

[badcooky]

ive got a set of S&S heads a local shop installed a .008 guide in a STD hole,needless to say,it cracked all the way thru the head.we install seats @ .008 & guides @ .002.heat/freeze on both to install.a properly installed seat should never move or come out
[/quote]

[harleytuner]

Follow up https://m.facebook.com/story.php?story_fbid=10154988443657181&id=100157792180

[bxbutch]

Well done THANK YOU Butch

[strobeen]

Very interesting. Could this valve seat problem be some of the cause of sumping ?

[rbabos]

Very interesting. Could this valve seat problem be some of the cause of sumping ?

No.
Ron

[Don D]

Interesting find
Easy fix with OS seat and properly putting a little more lead on the seat ring.

[rbabos]

Interesting find
Easy fix with OS seat and properly putting a little more lead on the seat ring.

What about the out of round bore , trashed from previous press. Don't you have to true the bores first? Otherwise press will be unequal around the seat.
Ron

[Don D]

In the seat and guide machine you just center and true over the hole and recut the hole enough oversize to clean and concentric to the guide axis. Then use an oversized seat ring to reestablish the proper press. I always sand the start of the seat ring to prevent any material being pulled in (the original problem ).

[WhipLash96]

  Maybe they can pressurize the primary with some of the blow-by so the trans lube will stay in the trans.

Makes me laugh when people state Harley quality is going down...they use to make some real junk.  Harley has always had an absurd amount of difficulty with design changes compared to Japanese bikes. The M8 will be fine once sorted.

Sure it will be sorted. In the mean time, I'll let others make donations to their bottom line while they take their sweet ass time solving issues and get it where it should have been in the first place. It was mentioned he EVO Sportsters had this issue at first. Does this company ever learn from their mistakes?
Ron

Absolutely love your question here Ron!

[rbabos]

In the seat and guide machine you just center and true over the hole and recut the hole enough oversize to clean and concentric to the guide axis. Then use an oversized seat ring to reestablish the proper press. I always sand the start of the seat ring to prevent any material being pulled in (the original problem ).

I know you will do it right as described above. Sadly, there will be some that just shove that seat into a damaged hole and call it done. I was only pointing attention to that square peg/round hole aspect.
Ron

[Thermodyne]

Seems to me, that the MoCo is trying to build modern heads with outdated practices.   

On the high end automotive side, seats for soft alloy aluminum heads are chilled with nitrogen and then dropped into place, to prevent damage to the head from interference pressing them. 

[1FSTRK]

Seems to me, that the MoCo is trying to build modern heads with outdated practices.   

On the high end automotive side, seats for soft alloy aluminum heads are chilled with nitrogen and then dropped into place, to prevent damage to the head from interference pressing them.

Same at HD for decades.

[jsachs1]

If you put a smooth radius on the seat lead in, proper interference fit, you should never have the problem.
John

[04 SE Deuce]

  Maybe they can pressurize the primary with some of the blow-by so the trans lube will stay in the trans.

Makes me laugh when people state Harley quality is going down...they use to make some real junk.  Harley has always had an absurd amount of difficulty with design changes compared to Japanese bikes. The M8 will be fine once sorted.

Sure it will be sorted. In the mean time, I'll let others make donations to their bottom line while they take their sweet ass time solving issues and get it where it should have been in the first place. It was mentioned he EVO Sportsters had this issue at first. Does this company ever learn from their mistakes?
Ron

Absolutely love your question here Ron!

Hey we're talk'n a company steeped in tradition here!   

[Moparnut72]

Seems to me, that the MoCo is trying to build modern heads with outdated practices.   

On the high end automotive side, seats for soft alloy aluminum heads are chilled with nitrogen and then dropped into place, to prevent damage to the head from interference pressing them.

That is how we put guides in '30's and 40's radial aircraft engines. Seats weren't replacable. Once the seats were worn out, ground too many times etc, the cylinders were discarded. When I ground seats I took off the least amount of material possible.
kk

[TorQuePimp]

If you put a smooth radius on the seat lead in, proper interference fit, you should never have the problem.
John

Or order them that way

Tucker,PPPC ,del west and others have a seat order form where you can write in particulars

   it helps alot

[Thermodyne]

OK, so here's a question.  Regardless of what error is taking place when the heads are built.   What are the ramifications to the end user?  That guy who will never pull the heads short of a failure?

Will the exhaust gas eventually erode the aluminum away from under the seat?

Will the seat run hot from improper cooling and cause any number of problems?  Early detonation all the way to burnt valves or dropped seats.

Or will those scooters just run a little more poorly, but give a lifetime of service?

[Don D]

Bent and dropped valve

[prodrag1320]

If you put a smooth radius on the seat lead in, proper interference fit, you should never have the problem.
John

100% agree'd

[1FSTRK]

OK, so here's a question.  Regardless of what error is taking place when the heads are built.   What are the ramifications to the end user?  That guy who will never pull the heads short of a failure?

Will the exhaust gas eventually erode the aluminum away from under the seat?

Will the seat run hot from improper cooling and cause any number of problems?  Early detonation all the way to burnt valves or dropped seats.

Or will those scooters just run a little more poorly, but give a lifetime of service?

If it will show up on a leakdown test it can cause some or all of what you listed.

[HD/Wrench]

Reminds me of the Floating guide in the early CVO 110 heads..  Some ran with the noise for many thousands of miles before they had a hard crunch failure. Just did a 07 that was " noisy"  No guide in the port on front ex head it had been moving up and down for a long time based on when the noise started..  The amount of oil it was pushing was the customer concern.. Dealer said that some CVO can be louder than others .. Guy rode the wheels off..   Head was junk at that point or at least would cost more to repair then to buy new .


New model new issues ..  HD will solve it as that is not something that can be a turn your head the other way .. But how many  are leaking ?? close to 450,000 heads in a year .. at what point is it a real issue to HD ?   

[harleytuner]

Reminds me of the Floating guide in the early CVO 110 heads..  Some ran with the noise for many thousands of miles before they had a hard crunch failure. Just did a 07 that was " noisy"  No guide in the port on front ex head it had been moving up and down for a long time based on when the noise started..  The amount of oil it was pushing was the customer concern.. Dealer said that some CVO can be louder than others .. Guy rode the wheels off..   Head was junk at that point or at least would cost more to repair then to buy new .


New model new issues ..  HD will solve it as that is not something that can be a turn your head the other way .. But how many  are leaking ?? close to 450,000 heads in a year .. at what point is it a real issue to HD ?

When it costs the share holders money.

[Nastytls]

New model new issues ..  HD will solve it as that is not something that can be a turn your head the other way ..

Don't they have an extensive history of doing just that?

How would anyone know this is happening without tearing the heads off. HD will just say that the leak down is within spec and there is no reason to pull the head. Even if you persuaded them to pull it under warranty, it looks like T-mann went to significant lengths to determine where the leak actually was, what tech at an HD dealer is ever going to do that?

[IronButt70]

. at what point is it a real issue to HD ?

When it costs the share holders money.

BINGO!!! We have a winner.

[HD/Wrench]

New model new issues ..  HD will solve it as that is not something that can be a turn your head the other way ..

Don't they have an extensive history of doing just that?

How would anyone know this is happening without tearing the heads off. HD will just say that the leak down is within spec and there is no reason to pull the head. Even if you persuaded them to pull it under warranty, it looks like T-mann went to significant lengths to determine where the leak actually was, what tech at an HD dealer is ever going to do that?

NONE ..

[HV]

If a HD Tech called the MOCO with excessive leak down #s......(A)they would not pay for him to check the Seats (B) they would just send a replacement Head and would want the old one back unmolested 

[harleytuner]

If a HD Tech called the MOCO with excessive leak down #s......(A)they would not pay for him to check the Seats (B) they would just send a replacement Head and would want the old one back unmolested 

What about cylinders and rings?  Or is there enough known issues that they know it's the seats?

[sfmichael]

pretty sure seats only

[HV]

If a HD Tech called the MOCO with excessive leak down #s......(A)they would not pay for him to check the Seats (B) they would just send a replacement Head and would want the old one back unmolested 

What about cylinders and rings?  Or is there enough known issues that they know it's the seats?

Of course they would want others checked as well but FYI We haven't seen ANY yet with Excessive Leak Down for any reason 

[harleytuner]

If a HD Tech called the MOCO with excessive leak down #s......(A)they would not pay for him to check the Seats (B) they would just send a replacement Head and would want the old one back unmolested 

What about cylinders and rings?  Or is there enough known issues that they know it's the seats?

Of course they would want others checked as well but FYI We haven't seen ANY yet with Excessive Leak Down for any reason 

  I haven't headed of any neither but ive had a few I've tuned that seamed lower than expected on power, I'm going too try to get then back in to check leak down,  they are both fully compliant so if there is exessive leak down they should be covered. Thanks

[HV]

Ive seen a few ( at Training ) that have been apart a few times...with way more leak down in one cyl compared to another .....( We check leak down on both Cyl as part of the Engine testing procedures for the Advanced Tuning Course )  we then Dynoed them...ones with equal low numbers made almost 6 or 7 more HP then ones with large leak down on even one CYL ....I think the Multi Valve Systems make any Leak down effect the Numbers more then a 2 Valve per head would ......we then lapped the valves and checked seat pressures etc and had Big improvements in #s ....I think the 4 Valve heads need more attention on a rebuild then the old 2 Valve ones.....we see this a lot on Multi Valve Jap bikes all the time but I think most or a lot of the HD Techs are not as fussy as they should be with making sure valves are properly seated

[harleytuner]

Ive seen a few ( at Training ) that have been apart a few times...with way more leak down in one cyl compared to another .....( We check leak down on both Cyl as part of the Engine testing procedures for the Advanced Tuning Course )  we then Dynoed them...ones with equal low numbers made almost 6 or 7 more HP then ones with large leak down on even one CYL ....I think the Multi Valve Systems make any Leak down effect the Numbers more then a 2 Valve per head would ......we then lapped the valves and checked seat pressures etc and had Big improvements in #s ....I think the 4 Valve heads need more attention on a rebuild then the old 2 Valve ones.....we see this a lot on Multi Valve Jap bikes all the time but I think most or a lot of the HD Techs are not as fussy as they should be with making sure valves are properly seated

I haven't had any in for tunes since all this came about,  the 2 I'm referring to were tuned over the summer and i was upset with the results as the exact same builds did significantly better on other bikes.   This may be the reason why and for piece of mind id like to check,  especially if I can find a warrantiable issue for my customer. I go through a checklist before the bikes hit the dyno, but a leak down isn't something I usually spend time on if it's just in for a tune and i didn't do any work to it.

[HV]

I agree that you may find better #s with a good valve lapping at the least........Just as an example at the factory we did 114 Kits...now these kits had been installed a number of times so they were not 100% to begin with .....when we were done they had to make at least 100 HP  or we Failed the course....we only did one CYL Head for each bike ( testing seat pressures seat width etc.  )....My Bike had only like 3% leak down on my Cyl I did when done...However the rear CYL that we did not check in depth  had 10% ....on the Dyno I made 103 HP....My Buddy's bike had 3% on both CYL and it made 108 HP .....  Moral of the story ....the M8s are VERY sensitive to Valve Work !

[FSG]

Moral of the story ....the M8s are VERY sensitive to Valve Work !

with 4 of them per head you'd expect that to be the case 

[Moparnut72]

When I worked in the aircraft shop with radials, I did all the valve work. It was interesting what I found.  After lapping them I put in spark plugs and tip them upside down and pour in mineral spirits to check for leakage. If I did it was either lap some more or get out the Neways and recut. On the Wright engines there was a known problem. The heads on those were screwed on to the cylinders permanently but were known to develop a leak at this joint. We checked for that with air pressure. The boss had machined a fixture to seal the cylinder and we had a sparkplug with air fitting welded to the base. I would then pressurize the cylinder with 120#'s to check the seam for leaks with soapy water.  Occasionally I would find a valve leaking even though it passed the liquid test. We even did 3 angle valve jobs on these ultra low tech motors and they came from the factory that way.

Another interesting thing I read in a rebuild article  in Hot Rod magazine was that minor seepage with the liquid test was OK.     I lost a lot of respect for those guys at that point. I can't imagine what the leakdown % would have been on that engine. And this from an outfit that is all about high performance engines. We always test ran our engines for 5 hours before we ever released them to the owner and then we always did a leakdown test to boot.  I wonder how often HD does it. I would hope they at least pull random engines to test as a quality control procedure.
kk

[04 SE Deuce]

Periodic lapping valves/seats on desmodromic (no valve spring) Ducati's is key to making/maintaining power potential.

[HV]

I always Lap Valves and check with Contact Cleaner ...if that dont leak by its sealing !

[sbcharlie]

i think this issue is a total joke.  yes there maybe some seat not installed correctly from the factory. the valve seats are not machined after the seats are installed. the valve seat profile are machined in the seat and then they are pressed in to the valve guide axis. a leak down test is not going to show a loose seat even if it had a .002 press fit.  lapping a valve in shows if if the valve seat is not sealing to a valve. not a good way to fix a problem.  i have a Newen TUG we use now since this issue has came up, have not seen a loose seat yet. i was taught by the best never lap a valve after a valve job. on heads with Ti valves you can not lap you will destroy the coating on the valve surface. you use prussian  blue to verify contact patch. it interesting how you guys on these forums talk about things and your ideas on how to address problem  sbc

[kd]

i think this issue is a total joke.  yes there maybe some seat not installed correctly from the factory. the valve seats are not machined after the seats are installed. the valve seat profile are machined in the seat and then they are pressed in to the valve guide axis. a leak down test is not going to show a loose seat even if it had a .002 press fit.  lapping a valve in shows if if the valve seat is not sealing to a valve. not a good way to fix a problem.  i have a Newen TUG we use now since this issue has came up, have not seen a loose seat yet. i was taught by the best never lap a valve after a valve job. on heads with Ti valves you can not lap you will destroy the coating on the valve surface. you use prussian  blue to verify contact patch. it interesting how you guys on these forums talk about things and your ideas on how to address problem  sbc

  on the process. That's my teaching too. Blue will show any short-comings and then you fix that properly. Valve lapping to me has always been to get a few more miles out of a head that can't immediately be fixed or is slated for the graveyard anyhow. The problem may be guides, stems or several other issues and not worth fixing. I have the lapping tools but Prussian Blue is the paste I use, not grit.

[sfmichael]

never been a fan of valve lapping either - just seems like a stop-gap measure to correct an issue that should be remedied by machining

don't know anything about Ducati's (other than they're fast and sexy) and if that's a known benefit then I say roll with it - I never knock something that is a proven benefit even if it goes against my instincts

[Ohio HD]

As Rick said about the Ducati desmo motors, they don't use valve springs, only precise rockers that open and close the valves against the cam lobes. Since they don't have a valve spring pounding the valve against the seat, you occasionally need to touch them up, and reset the rockers if needed.

[BVHOG]

I would like an exact explanation of why lapping valves is harmful other than the Ti valves being damaged.

[sbcharlie]

Because your destroying the contact seat surface
My thoughts do what you think works  think about it
Just a Harley Davidson again you genius on this
Board crack me up better yet use a drill and some gas
Line and power grind them in .lots of Fred flintstone ways
To do things and it's amazing it works get some real
Course compound they grind in a lot quicker

[1FSTRK]

Because your destroying the contact seat surface
My thoughts do what you think works  think about it
Just a Harley Davidson again you genius on this
Board crack me up better yet use a drill and some gas
Line and power grind them in .lots of Fred flintstone ways
To do things and it's amazing it works get some real
Course compound they grind in a lot quicker

And to think BV was just defending you not so long ago. Must be tough teaching us humans, you being a god and all.

[sbcharlie]

What are you talking about  I think this a very stupid topic  I forgot use
Use a course toothpaste to finishing lapping.

[1FSTRK]

What are you talking about  I think this a very stupid topic  I forgot use
Use a course toothpaste to finishing lapping.

You come here as some kind of expert in the field, a man asks why a practice that once was common place is no longer thought of as a good idea and your response is arrogance, sarcasm, and now the question and topic are stupid. Class act.

[sbcharlie]

I have been doing this for over 50 years
And you know what you really annoy me

[1FSTRK]

It is never my intention.

[kd]

 

BV, one of the big reasons for me is that you are lapping a valve that is in a guide that most certainly has clearance (and therefore wobble) and if it is in a guide that has miles on it it is usually bell mouthed and out of round from the rocker valve stem travel on top of that. The cup and stick is being rocked back and forth and the grinding compound is not effective in creating a concentric pattern. If the stick is not rotated a full 360* you can change the seat to the worse. As you know, the valve rotates continuously in operation.

If you have a multi angle seat the contact area will be thin and wear a groove in the opposite seat surface. Any preset interference angle between the seats ground to ensure narrow seating (and therefore a better seal) will be destroyed (especially if done on a fresh grind). The proper seating area on the valve face can me moved to a higher or lower position on the valve face when lapped and a proper narrow seat width on the valve face can become wider.

I have used fine compound when machinist's blue was not available, but just to put a track on the seat and valve face to get witness marks for checking the seat(s) for pitting, damage or uneven contact. Those things show up when you frost up the surface lightly with lapping compound buff marks.I have also lapped pitted seats etc. to get another week or 2 out of an engine while waiting for parts and the machine was needed. I just don't agree that lapping is a repair / build procedure. That's me, anyone else is welcome to take another stance.

[Admiral Akbar]

i think this issue is a total joke.  yes there maybe some seat not installed correctly from the factory. the valve seats are not machined after the seats are installed. the valve seat profile are machined in the seat and then they are pressed in to the valve guide axis. a leak down test is not going to show a loose seat even if it had a .002 press fit.  lapping a valve in shows if if the valve seat is not sealing to a valve. not a good way to fix a problem.  i have a Newen TUG we use now since this issue has came up, have not seen a loose seat yet. i was taught by the best never lap a valve after a valve job. on heads with Ti valves you can not lap you will destroy the coating on the valve surface. you use prussian  blue to verify contact patch. it interesting how you guys on these forums talk about things and your ideas on how to address problem  sbc

Charlie, I suspect you might want to get your facts straight..  Unless of course this is wrong..

https://www.youtube.com/watch?v=FGg3ojioeiM

go to 7:30 in the video..

This makes more sense than your sense.. T man is right on as far as I can tell.

[Don D]

I avoid lapping. Why?
Take a valve that has been lapped and put it in the valve grinder. Just start to kiss it with the stone and watch how it cleans up. Tells a story about how the face is no longer flat.
That said there is a time and place for a light lap with fine compound. I do this occasionally.
When the valve guide clearance is tightened up concentric seats become critically important. Lapping is not a substitute.

[Durwood]

I added leak down and sump test to the M8 prerequisite list before disassembly, I did a stage 2 on one today and leakage was almost nothing, just like my test bike, less than 1%.

[HD/Wrench]

Sounds good but its to the point that we are checking for all this on these bikes so now its CCP test, Fuel psi test, Leak down and a sump test.   Cost will go up for sure.. Then add the break in fee .. 

[BVHOG]

BV, one of the big reasons for me is that you are lapping a valve that is in a guide that most certainly has clearance (and therefore wobble) and if it is in a guide that has miles on it it is usually bell mouthed and out of round from the rocker valve stem travel on top of that. The cup and stick is being rocked back and forth and the grinding compound is not effective in creating a concentric pattern. If the stick is not rotated a full 360* you can change the seat to the worse. As you know, the valve rotates continuously in operation.

If you have a multi angle seat the contact area will be thin and wear a groove in the opposite seat surface. Any preset interference angle between the seats ground to ensure narrow seating (and therefore a better seal) will be destroyed (especially if done on a fresh grind). The proper seating area on the valve face can me moved to a higher or lower position on the valve face when lapped and a proper narrow seat width on the valve face can become wider.

I have used fine compound when machinist's blue was not available, but just to put a track on the seat and valve face to get witness marks for checking the seat(s) for pitting, damage or uneven contact. Those things show up when you frost up the surface lightly with lapping compound buff marks.I have also lapped pitted seats etc. to get another week or 2 out of an engine while waiting for parts and the machine was needed. I just don't agree that lapping is a repair / build procedure. That's me, anyone else is welcome to take another stance.

Thanks for the detailed answer without all the other BS, makes sense.

[Gordon61]

...Unless of course this is wrong..

https://www.youtube.com/watch?v=FGg3ojioeiM

go to 7:30 in the video..

This makes more sense than your sense.. T man is right on as far as I can tell.

...they also mentioned leak testing after the seats are cut ??

[HD/Wrench]

BV, one of the big reasons for me is that you are lapping a valve that is in a guide that most certainly has clearance (and therefore wobble) and if it is in a guide that has miles on it it is usually bell mouthed and out of round from the rocker valve stem travel on top of that. The cup and stick is being rocked back and forth and the grinding compound is not effective in creating a concentric pattern. If the stick is not rotated a full 360* you can change the seat to the worse. As you know, the valve rotates continuously in operation.

If you have a multi angle seat the contact area will be thin and wear a groove in the opposite seat surface. Any preset interference angle between the seats ground to ensure narrow seating (and therefore a better seal) will be destroyed (especially if done on a fresh grind). The proper seating area on the valve face can me moved to a higher or lower position on the valve face when lapped and a proper narrow seat width on the valve face can become wider.

I have used fine compound when machinist's blue was not available, but just to put a track on the seat and valve face to get witness marks for checking the seat(s) for pitting, damage or uneven contact. Those things show up when you frost up the surface lightly with lapping compound buff marks.I have also lapped pitted seats etc. to get another week or 2 out of an engine while waiting for parts and the machine was needed. I just don't agree that lapping is a repair / build procedure. That's me, anyone else is welcome to take another stance.

Thanks for the detailed answer without all the other BS, makes sense.

Like trying to cut a seat with a pilot that is not tight in the guide .. Same thing in reverse  A full radius type cut on the seat + lapping will show up very fast and in  most cases create more damage than it will ever solve.  I posted that up years ago now. A customer decided to lap the fresh heads for what ever reason. Then filled the ports with fluid and they leaked.  He was complaining about it on here  .. Took them to zippers , they looked at it and did a new valve job.. Told him to stop doing that .. " paraphrasing on my part "