1.940 valves on stock seats

[prodrag1320]

got a set of TC heads in for some SERDI seat work,after cleaning them i noticed they were stock seats with 1.940 valves,these were from a well know,all over the internet,better than sliced bread shop.i put them on face book just for a chuckle (didnt "out" the shop) and was surprised how many "high perf" shops do this.NOT A GOOD IDEA AT ALL!!! if looking to go with anything bigger than 1.900,MAKE SURE YOUR SHOP IS INSTALLING OVERSIZE SEATS!!

[Hillside Motorcycle]

1.900" is the limit on an OEM seat.
1.940"-up have new seats installed here, and is easy to do if so equipped.

[Buglet]

   It depends who is doing the work. I found out a lot of things about different shop including some vendors on here which I will not get into.

[FLDavetrain]

Likewise. I have the goods on a vendor that would make people's stomach turn

[PoorUB]

Too large of valve on a stock seat, wouldn't  you lose flow over stock?

[prodrag1320]

Too large of valve on a stock seat, wouldn't  you lose flow over stock?

A stock seat has a OD of 1.930,when installing a 1.940 valve,half the actual 45* seat is in the aluminum

[Don D]

March 1 2001, article by Joe Mondello in Engine Rebuilder Magazine recommended this practice.  Not a recommendation by me or endorsement just an observation.

I put in new seat rings and have done so for the last 8 years. Easily done with counterbore cutters on my  Serdi.

[prodrag1320]

March 1 2001, article by Joe Mondello in Engine Rebuilder Magazine recommended this practice.  Not a recommendation by me or endorsement just an observation.

I put in new seat rings and have done so for the last 8 years. Easily done with counterbore cutters on my  Serdi.

Not doubting you,but I'd love to read that article.no clue how it could be ok to use a 1.940 valve on a seat not even as big as the valve

[CVOThunder]

Kirby, thanks for explaining this earlier on FB. I was cornfused on the .040 being the limit but not anymore.

[Don D]

It can be done safely but all advantages of the larger head are canceled out by the seat being lower on the valves seat. Something done on stock rebuilds, centering the seat on the valves face. Done differently when performance is the goal.

[aswracing]

got a set of TC heads in for some SERDI seat work,after cleaning them i noticed they were stock seats with 1.940 valves,these were from a well know,all over the internet,better than sliced bread shop.i put them on face book just for a chuckle (didnt "out" the shop) and was surprised how many "high perf" shops do this.NOT A GOOD IDEA AT ALL!!! if looking to go with anything bigger than 1.900,MAKE SURE YOUR SHOP IS INSTALLING OVERSIZE SEATS!!

Many years ago, a set of heads came into our shop that literally had 2" valves on the stock seats. I wouldn't have even believed it could be done until I saw it. The seat was basically just a sliver of thin steel. The 45 was well into the aluminum, and high up on the valve face. It's a wonder the seat hadn't fallen out.

Too large of valve on a stock seat, wouldn't  you lose flow over stock?

That's exactly right, and it's what HD Street Performance is getting at in his post above. You generally place the contact point ("the 45") anywhere from about the middle of the face on the valve to the outer edge. It's placement is a trade-off between flow and life. But when the seat o.d. is too small, you can't do that. You're forced to place it higher up the valve face. That doesn't do you any good from a performance point of view. At the end of the day, the valve is the plug and the hole size constrains the flow. If you're not making the hole bigger, making the plug bigger isn't going to help flow. In fact it could hurt it.

[PoorUB]

Too large of valve on a stock seat, wouldn't  you lose flow over stock?

A stock seat has a OD of 1.930,when installing a 1.940 valve,half the actual 45* seat is in the aluminum

That shouldn't be a problem!

[SP33DY]

March 1 2001, article by Joe Mondello in Engine Rebuilder Magazine recommended this practice.  Not a recommendation by me or endorsement just an observation.

I put in new seat rings and have done so for the last 8 years. Easily done with counterbore cutters on my  Serdi.

Not doubting you,but I'd love to read that article.no clue how it could be ok to use a 1.940 valve on a seat not even as big as the valve

Here's a link to a later reprint of Joe Mondello's article. I knew Joe pretty well and I suspect that there's a back story to this. 

http://www.engineprofessional.com/EPQ3-2010/mobile/index.html#p=52

[Don D]

Too large of valve on a stock seat, wouldn't  you lose flow over stock?

No, but you would not be able to get any more flow than a 1.9" valve, the throat gets opened up over stock and the seat moved out some. Then the rest of the port needs a remodel. 

From Mondello:
"Many think if you install a 1.94 intake valve you must replace the seat - no you don't"

But with all due respect, this was a long time ago and we have come a long way. Personally I no longer even use the 1.94 valve. I go right to a 1.98 or 2" depending on the build. And all the talk about Neways, no thanks. I realize he was trying to help ham and eggers, I knew the man, good guy. He cleaned my clock on a grudge night at Lyons many years ago.

[jsachs1]

 I've had heads come in here with 1.900" intake valves, where half the 30 degree top angle has flaked off. You see it all in this business.

1- pic bad guide, customer said the bike ran great.

2- pic customer tried to install his own compression releases.

John

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[attach=1,msg1348102]

[MadMaxUK]

trying to help ham and eggers

Ham and eggers  that takes me back. I was half expecting the words 'donut cam' in the next sentence 

[Hossamania]

The picture where the customer tried to install his own compression releases, "I don't need no jig, it ain't rocket science."

[aharp]

March 1 2001, article by Joe Mondello in Engine Rebuilder Magazine recommended this practice.  Not a recommendation by me or endorsement just an observation.

I put in new seat rings and have done so for the last 8 years. Easily done with counterbore cutters on my  Serdi.

Beat me to it. I remember that article. He was recommending 89% throat to valve too if I recall correctly?

[FSG]

John  what was the go with the spark plug hole ?

[aharp]

Anyone know what became of Kyle Mathews that was partnered up with Mondello? They had a website touting their heads and "engines run on math" blah blah but are nowhere to be found now. Guy seemed to work hard at pushing his product but never saw any actual pulls on his heads to back anything up.

[jsachs1]

John  what was the go with the spark plug hole ?

Plug hole is OK. Maybe a piece of carbon that makes it look like a flaw. The exhaust guide was sawed through, causing the valve to not hit the seat squarely. Customer said the bike was running well. Valve protrusion geometry vs. rocker box combo problem.
John

[TorQuePimp]

Anyone know what became of Kyle Mathews that was partnered up with Mondello? They had a website touting their heads and "engines run on math" blah blah but are nowhere to be found now. Guy seemed to work hard at pushing his product but never saw any actual pulls on his heads to back anything up.

After mondello died he gave up on the project
Casting patterns were done at profiler in new Carlisle Ohio
Darin Morgan had a .200 raised port with a 2" valve that flowed 308@.600@28°
Don't know anything beyond that

[FSG]

 

[Derekcoor04]

Question for you head guys. I had my 02 heads ported,polished,and decked but kept stock valves, can i install 1.9 intake and 1.585 exhaust valves without having seats recut?

[Hillside Motorcycle]

Question for you head guys. I had my 02 heads ported,polished,and decked but kept stock valves, can i install 1.9 intake and 1.585 exhaust valves without having seats recut?

Absolutely not.

[Tail Ridr]

Question for you head guys. I had my 02 heads ported,polished,and decked but kept stock valves, can i install 1.9 intake and 1.585 exhaust valves without having seats recut?

Where do you get a 1.585 or basically 1.59 ex valve? Have looked around some and don't find much listed beyond the normal sizes, or are they turned down?

[04rkryder]

If you're talking 5/16 stem, AV&V has a 1.585 exhaust valve (AV1585)

[Derekcoor04]

yeah that's what I'm talking about is 5?16" valves< and yes it was AV&V.