Why won't idle come down

[96flhpi]

When I stop at a light my idle is high unless I bring it down manually with engine braking or releasing the clutch just enough to engage ever so slightly.  Since it's got points I figured the mech advance was shot but new advance, same thing, old advance with new springs no better. 

Don't think it's intake leak because I can bring it down with the clutch and once it's down it goes to the same RPM every time and is rock steady once it's there.  I had checked and replaced the seals before ordering new advance even though it didn't show any evidence of a leak. 

FWIW I've always had better luck getting a consistent idle with the silver advance springs and am using them this time.  Maybe they're crap since they were $9 for a bag of 10 instead of the $25 for 2 I saw at J&P.

Anybody know what else might cause this behavior?

[motorplex88]

I have had this happen like you are describing. For me it indeed ended up being a crack in one of the intake bands. Not sure what carb your running but mine is the old Bendix. I would take a look.

[JW113]

This is classic symptom of advance unit sticking. A crack in the intake seals is the same as the throttle being open. If it runs at high rpm, then forcing it to drop rpm by using the clutch/brake and it goes back to normal doesn't seal the leak in the intake. What you are describing is the advance weights getting stuck in the advance position. Just my thoughts, could be wrong. Usually am. LOL!

Don't know what you're using for a mechanical advance, but I can't stress enough don't go cheap. Get the Rivera, keep it lubed up, be done with it.

-JW

[motorplex88]

I'll agree with JW in the statement about a crack {leak} in the intake would remain a constant....you would think. I found in mine that not to be true. It was a fine hair line crack that I had to take the carb off and look good to find it. I would have thought I would find it with the ol shoot brake clean method. Changed the bands and problem went away. Go figure. I missed the part where you said you changed your intake seals so you most likely have that issue covered. I'll shut up now.

[96flhpi]

Thanks for replies.

That's weird Motor - I was gonna say every time I've had a leak I've had to fiddle with the idle adjust constantly so it can't be that, but I guess I can't rule it out.  It's been exactly the same before and after the seal change though.

JW I replaced a 15 year old Rivera with an American Prime unit, supposedly made by a former Rivera employee.  It's US made, cost as much as the Rivera, and looks EXACTLY the same as the Rivera other than the name on the weights.

My new thought is that maybe the can of white lithium grease I've been using as lube has gone bad.  Does that stuff have a shelf life?  I've been using the same can at least 10 years - at beginning of season I disassemble unit, clean, spray on lithium, let it set, it leaves a film behind and there's very little fling off.  When I pulled the advance last night there was a small pool of liquid grease in the bottom of the cone (usually there's so little I can clean it with a q-tip but this took a few paper towels) and the unit looked pretty dry.  I redid the unit with wheel bearing grease but won't get to test it until tonight. 

Might explain why it seems fine when I first redo it but comes back within 3-4 miles, and why it's happened with more than one advance.  I thought it may have to do with the unit heating up but maybe it's just flinging off all the lube.

[JW113]

Yes, lithium grease aka Lubriplate does go bad. Starts off fairly white, turns into what looks like hummus over time and gets thicker That's the oil oxydizing. Personally, I would not use lithium grease in a high temp application. For the advance weights and other places on the motor that need some lube, I like that high temp caliper grease.

-JW

[motorplex88]

Good idea on the caliper grease. I usually just used the grease from those little pills that comes with ignition points. Never have known what that stuff is.

[Hossamania]

I always used that grease too, way back when I changed points on my cars a million years ago. I was told it was non-conductive, and that regular grease was not recommended.

[Dogbone45ACP]

I use anti seize on advance units . What ever brand you like. Works well.

[kd]

White Lubriplate is formulated to absorb water and prevent rust spotting in stationary load bearing surfaces.  I agree that you need to use a high temp lube with stringy cling characteristics.  The kind that is hard to clean up with a dry towel because it leaves a film.

[JW113]

This is what I use. You don't want grease getting on the disk, so it tends to stay in place even with high temps. Which seems to make it work good on hot ignition parts.

[attach=0]

-JW

[96flhpi]

Installed unit with the wheel grease lube, went for a 40 min ride, everything was great for 35 mins of it and last 5mins problem returned.  Pulled the points plate and advance is plenty lubed still.  Thinking ok problem comes with engine fully warmed up, but previously I've replaced the unit on an engine that only cooled for the time it took me to do the exchange and it's been good at first and returns after 5 mins.

But now I'm back to maybe it IS a small air leak.  I did have the heads off for a valve job not long ago, and yes I re-torqued after installation, but maybe it's a small head gasket leak, or intake leak that I failed to fix first go around - and also yes the heads were clocked to the intake.  It started maybe a week after the heads were reinstalled, in fact I think it started after the final retorque.  Gonna pull the heads and start over because I'm outta ideas.  Hopefully I didn't pull an insert.

On that note, I have copper and blue teflon head gaskets on hand (I usually use James Fire-Ring).  The teflons are probably 8 years old, do they have a shelf life?  If they do I'll try the copper, but prefer the teflons just because I've never tried the copper before.

Also, FWIW, I've been using that white lithium to lube the advance for like 13 years, never had a problem.  In fact it was most likely suggested by someone here, back in the MSN days.

Thanks again for any advice.

[PoorUB]

I seriously doubt it is a head gasket. When I head gasket starts to leak they blow out fairly quick and you start hearing a chirp.

How many miles since the problem started?

[xlfan]

What kind of carb?

[96flhpi]

UB - I know I've filled up the gas 3-4 times so 400-500 miles maybe, haven't been keeping track.

XL - It's happened with two different Keihin CV's and the original butterfly so probably not the carb.  I thought carb too after it came back with the new weights.

I read that too much advance can cause this so when I set the timing after installing the advance last night I retarded the timing maybe 5 degrees just to rule it out, but that wasn't the problem.

I too doubt it's a head gasket but other than an air leak of some kind I'm all out of ideas.  The only reason I'd pull the heads and start over is because I have all the gaskets I need on hand and have been chasing this for 2 weeks - if I redid everything I could be up again over the weekend.  I also commute on this bike so don't want to be putting on a lot of miles if it's possibly a leak and do damage, although the oil temp (tank gauge) has been normal.

[guppymech]

In my experience with car engines, a vacuum leak causes rough running and a lower idle rpm.  The presence of a vacuum leak could be verified by cupping your hand over the carburetor inlet with the engine at idle, if the idle sped up and smoothed out there was a leak somewhere.  Slightly blocking the carb inlet with your hand gives a richer mixture that corrects for the vacuum leak.

What year is your engine and do the heads use o-rings or bands?  My heads use bands and I find I get a better intake manifold seal using 4 thin wormscrew clamps than either the stock or aviation style clamps.

It may be a crack that needs a full heat soak to open up enough to cause problems.  From a cold engine it takes a good ride to act up but the time you changed the advance unit on the hot engine the problem came back in 5 minutes as she cooled a little during the iggy swap.

I will say, anytime I've had a motorcycle engine idle take off like yours it's been from the advance unit, both my old Norton and current FXE.  They wouldn't do it like clockwork, just once in a while with the Norton being way worse.   Do you have a stock H-D advancer you could try?

My take on head gaskets.  I'm using Cometic .032 copper, coated with Permatex Copper Spray-a-Gasket torqued to 55 ftlbs with no leaks.  The gaskets are reusable after annealing with a propane torch and cleaning off the scale.  I'd anneal the new gaskets before you use them also.

Sorry I'm all over the place with my post but this is a odd problem you have that is difficult to troubleshoot over the internet.

Tom

[xlfan]

Have you blocked unused vacum ports on the carbs?   

[Burnout]

Put a timing light on it when it is acting up, to see if it caused by the advance not rolling back.

Any vacuum leak would cause driveability issues.

[JW113]

You mentioned two CVs, where/how do you have the enrichener cable mounted? Is there any chance the enrichener is opening slightly, which will also cause a high idle. Doesn't explain the stock butterfly carb doing it also, but something to check I suppose.

-JW

[kd]

If it was an intake issue I doubt after forcing the idle down with the clutch in gear it would stay there as you say.  I suggest you go back into the advance unit and blueprint it.  Just because you have new springs, doesn't mean they are not screwing up by not pulling the weights back at lower RPM. There may be a bent post or the weight(s) may be dragging or hooking on something on return. Did the plate get warped when installed by the way it was set in place?

After 3 carbs it probably isn't that.  It could be a manifold problem but as I said it doesn't pick back up with the clutch in. Spraying the manifold seals will test them anyway. This sounds to me like the advance plate is hanging up for some reason.

I would try to polish all contact points and check for damage that may be causing a tight spot on return.  If you shut it off when the idle is high does it restart at a high idle or start out low again? Can you run it with the cover off so you can see if it returns?

[Racepres]

Just for "Potty mouth"s and Grins... replace the condenser with a known good one... I have had them go Flakey... especially "new" ones...
Generally however... bad condensers either simply won't run... or Fire up fine, but will Not pick up RPM...

[JW113]

This is a bit extreme, but if you suspect an intake leak, here is what we do with old Indians to locate intake leaks, which are kind of common with their funky manifold to head spigot compression joints. Get a 1-7/8 or 2" rubber stopper from ACE or True Value or where ever, drill a hole in the middle. Roll the motor over until both intake valves are closed. Pull the carb, force the stopper into the intake manifold hole, and use a compressed air blow off gun to blow air into the manifold. KEEP THE AIR PRESSURE LOW, like 5-10 psi. Then use soapy water sprayed around the intake manifold joints, head gaskets, etc, and look for bubbles. We call that "the bubble test". Clever name, eh?

-JW

[david lee]

This is a bit extreme, but if you suspect an intake leak, here is what we do with old Indians to locate intake leaks, which are kind of common with their funky manifold to head spigot compression joints. Get a 1-7/8 or 2" rubber stopper from ACE or True Value or where ever, drill a hole in the middle. Roll the motor over until both intake valves are closed. Pull the carb, force the stopper into the intake manifold hole, and use a compressed air blow off gun to blow air into the manifold. KEEP THE AIR PRESSURE LOW, like 5-10 psi. Then use soapy water sprayed around the intake manifold joints, head gaskets, etc, and look for bubbles. We call that "the bubble test". Clever name, eh?

-JW

ive done the soapy thing before but not your one.makes complete sense

[JW113]

Another less conclusive way, but can work as well, is to take a spark plug out, crank the motor over to get that on the intake stroke (valve open), leave the carb on, and use the compressed air into the spark plug hole. You'll pressurize the intake manifold and carb a little. The throttle plate won't hold back the air, but with higher pressure (60psi or so) it will be enough to expose any leaks and make bubbles.

-JW

[96flhpi]

Thanks all for replies.  I'll tell you latest in the saga first then answer your ?'s after.

After work decided to see if it's still "everything perfect until engine fully heated."  It is.  However tonight, with butterfly carb, it coughed enough to stall the bike at start up (usually coughs a few times when dead cold but not enough to stall bike), ran perfectly once warmed up enough to take throttle - no coughs, no hiccups - for around 1/2 hour.  Then the high idle returned and started to get an occasional hiccup if I gunned it off coasting, then coughs at stops, then coughs at stops that'd stall bike.  Easy, now it's an obvious intake leak, right?

Problem is, that is what this carb's M.O. is - every few years I get both nostalgic and forgetful and put it back on and it runs perfectly for a week, then needs constant A/F adjustments, then by the end of the second week it's coughing so much I replace it with the CV.

Since I'm putting the CV back anyway I pulled the intake to inspect the rings and although they're not torn or split I did find that while one had a clearly defined witness mark around the entire circumference where it filled the intake/head gap, the other had the defined mark around 2/3 or so then the mark blurred to where I was questioning whether I could see it or not.  I'm seriously hoping Motorplex hit on it early on.  I have been keeping the clamps a little looser since I overtightened them and caused a leak a few years ago but made them tighter with new rings.

Guppy - it's got O-ring style intake.  When you say vacuum leak do you mean an intake/gasket leak?  If not there's no vacuum system to leak.  And no, don't have an OEM advance to experiment with.

XL - both CV's VOES ports gunked over with silicone and capped with a little plastic cap.  Doesn't mean they can't have opened but the butterfly has no VOES port.

Burnout - not sure if that would help.  Wouldn't the timing show advanced whether the weights were being held open from binding or the usual centrifigul force? 

JW - CV choke mounted to engine mount between heads, butterfly choke on dash, checked both early on in the process.  Great advice on the intake leak checker.  I've seen machinists make them out of aluminum and an old inner tube but I'm not a machinist.  Your's only requires the tools I already have.

KD - this has happened with three different units - old Rivera, brand new American Prime, and one cobbled together from spare parts of crappy Chinese ones.  Tried 2 sets of springs on the Rivera and 3 on the American Prime.  Oddly enough the cobbled together one lasted the longest before the problem came back.  Restarts at normal idle until I give it throttle then hangs up immediately.  Can't see the weights running the points plate blocks them.

Race - it's my also experience that condensers typically either work fine or they don't at all.  But unless these new intake seals are the answer I'll give it a try.

Thanks again everyone, rainy tomorrow so back at it Saturday.

[capn]

These problems are a pain.Either advance unit or intake.Try riding the bike till it acts up with points cover off.Without burning yourself take out advance unit and put one in without the weights on it and see how it idles.If good its probably the advance.

[Racepres]

Tho it is not "correct" I always take a wrap of cheap electrical tape over O-rings at Manifold... it is also Vital to use the Correct Intake Clamps...split ones are for Rubber Bands..and Solid aircraft type are best for O-ring... But... yea...all old news!!!
BYW I have had problems with the 2-piece Clamps... But I'm thinking the Chrome ones were worse than the brass ones... or? Been awhile... may be bassackwards!!!

[JW113]

Here's a crazy thought that might point to an intake manifold leak. So this only happens when hot, yes? And when hot it stays bad, but when cools down idle is OK, yes?

So what happens when it get hot? The cylinders and heads grow a little bit, pulling away from the intake manifold a little bit. Which, if the seal at one of the joints is marginal, a small crack might open, and thus your intake leak.

It's a theory anyway!

Are the flanges on the heads and intake manifold, where the O-rings seat, clean as a whistle? I polish the ones on mine with Scotchbrite pads to make sure they're glass smooth.

-JW

[96flhpi]

These problems are a pain.Either advance unit or intake.Try riding the bike till it acts up with points cover off.Without burning yourself take out advance unit and put one in without the weights on it and see how it idles.If good its probably the advance.

This is a great idea, but the points cam would flop around too much with no weights.  But if I locked the weights down with wire instead of springs it could be useful.  I've even got that cheapo cobbled together advance I could sacrifice if it comes down to needing to lock them down with epoxy or similar. 

Race - I'm using the solid aircraft clamps.  Last night during the seal swap I clamped them on the intake (off bike) with no seal just to see if there was even clamping all around and other than maybe .010 gap (if even) after where the clamp band overlaps it's perfect.

[96flhpi]

Here's a crazy thought that might point to an intake manifold leak. So this only happens when hot, yes? And when hot it stays bad, but when cools down idle is OK, yes?

So what happens when it get hot? The cylinders and heads grow a little bit, pulling away from the intake manifold a little bit. Which, if the seal at one of the joints is marginal, a small crack might open, and thus your intake leak.

It's a theory anyway!

Are the flanges on the heads and intake manifold, where the O-rings seat, clean as a whistle? I polish the ones on mine with Scotchbrite pads to make sure they're glass smooth.

-JW

Yeah JW that's my new theory until I can test the newly installed intake tomorrow.  Gonna pick up some of that caliper grease you recommended and relive the advance too.

Flanges are clean, not scothbrited or anything, but as clean as they usually are whenever I've installed the intake.

[kd]

If possible, do each modification separately.  It would be interesting to find out which "guess" rersolves the problewm.  Doing both together will muddy the water.

[capn]

I converted mine over to band style with the plastic spacers cant remember who sells them.Also there is a guy in Fla. that sells a kit with four narrow worm clamps with the bands.Thats what cured mine.FnA custom cycles.

[Racepres]

I converted mine over to band style with the plastic spacers cant remember who sells them.Also there is a guy in Fla. that sells a kit with four narrow worm clamps with the bands.Thats what cured mine.FnA custom cycles.

Something I will Never do again, a Fix for a non Existent Problem... but, I actually prefer o-rings... less problems...
Worm Clamps do Not form a Perfect Circle like the proper aircraft [or O.E.] clamps... also not for me...,
Do What works for you.... but mine have not been a problem in the 30 plus years I have owned them!!!

[capn]

Yes but those four separate clamps can seal a slight misalignment easily.Instead of putting the bands in a bind with one wide clamp it tightens on the heads and manifold separately .

[Racepres]

Yes but those four separate clamps can seal a slight misalignment easily.Instead of putting the bands in a bind with one wide clamp it tightens on the heads and manifold separately .

Not been My Experience... the O.E clamp is Split for this reason..and does a better job...IMO... Only
Your Experience, may be different...

[capn]

I wasnt aware that they were still selling OE shovel clamps.

[u4hd2]

27063-80 is what I like best for the band type seals. Clamp around a socket the same size as the intake and tighten the brads with a punch. Now its a perfect fit.

[96flhpi]

WOW this is the most frustrating thing I've had to deal with on this bike, it's just getting worse.  Cleaned out CV and put back on, impossible to start, coughing constantly (48/180 jets, don't remember how may turns on A/F but haven't had to touch any of this for years), stalling constantly, flames out of carb (tested with no air cleaner), choke had little effect meaning it raised idle just slightly when out.  Once I had it running high idle was there on first twist of throttle.  Ran it up the driveway just for a test and it bogged down like it was super rich.  Once it was running choke did nothing but make it run rough no change in rpm.

Sprayed brake cleaner at both sides of intake and around head gasket are and no change at all in idle, tried different choke cable and same crap.

Gonna stay away for now and try the other lube tomorrow and a new condenser.  If I remember right hard to start is a sign off a bad condenser.

[guppymech]

A new condenser should help with the recent worse symptoms.  My first car had a condenser go bad over the course of one evening and I was lucky to get it home.

[Hossamania]

When I was a young man, every new set of points got a new condenser.

[96flhpi]

Yeah Racepres - this particular carb was on bike for years and working fine when removed.  It was only replaced to see if it was causing the idle problem.

[JW113]

Have you put a timing light on it yet?

-JW

[96flhpi]

Have you put a timing light on it yet?

-JW

No - I'm confused as to what info that would give me.  If there's a leak causing rpms to go up centrifugal force is gonna open the weights and show advanced and if the weights are stuck open it's gonna show advanced too.  What am I missing? 

Just got back from auto store to pick up the lube.  Also, since I'm thinking issues may be separate I was gonna try a different coil if new condenser does't solve the coughing issue - pulled the coil cover last night but didn't help.  I know I have a good 3 ohm, think I have another 5 ohm.  Am I remembering right that the problem with 3 ohm on points is only that it causes faster wear meaning for test purposes it isn't an issue?

[JW113]

What info indeed. Let me waste everyone's time with a little anecdote.

My old truck (w/ small block 400 V-8) started pinging badly with anything but the slightest amount of throttle. And I mean BADLY. Has to be something in the timing, yes? I checked it at idle, spot on 8 deg BTDC. I dialed it back to zero, no help. Advance mechanism sticking or opening too fast? I took it all apart, cleaned & lubed, back together and no help. I put a mark on the damper at 35deg and checked the timing from idle to about 3000rpm, timing was advancing correctly. Maybe a vacuum leak? I plugged a the brake, vac advance, and PVC lines, no help. Carb running too lean off the idle circuit? I took the carb (Quadrajet) to a pro carb rebuild shop. $400 later, I had a completely refurbished carb, and... no help. Running low on ideas, I bought a new distributor. In the process of putting it on, I decided to have a look at the plugs. All looked OK but cyls 4 and 6 looked "funny". As in different than the other 6. Since the plugs were out, just for fun I decided to do a compression test. All were about 150 psi except for... you guessed it, 4 and 6. The culprit in all of this was not the carb, not the ignition, not a vacuum leak, but a blown head gasket. Blown right at the seam between cyls 4 and 6, they were talking to each other, and hence the bad detonation. Had I done the basic diagnostic homework first, would have saved myself a LOT of time and money. Lesson learned.

The moral of this tale: Don't assume anything! Collect all the diagnostic info you can, whether you think you need to or not.

Since you have not actually checked the timing, you don't know with 100% certainly that it is set correctly. Right?

Just sayin'...!

-JW

[96flhpi]

I thought you meant it'd tell me if weights are open or not which I figured "yeah they're open but why?"

So new condenser, caliper lube on advance.  Noticed I had previously pinched the coil wire at some point during my many swaps, while shrink tubing over the exposed wire noticed the wire to the spade connector was starting to fray.  So no broken insulation and fresh spade and no more coughing at idle, choke behaves as it should.  However high idle still there even on cold engine now, and bogging down under load remains.  Throttle response is normal (except the high idle) when stationary but won't take more than the slightest throttle while in gear, any more the carb coughs and spits gas.

While cycling through with the the kicker I noticed the intake stroke doesn't feel like it's sucking my thumb on the plug hole as much a usual.  Installed plugs and cycled through and I can hear air coming out of the carb throat.  Pulled rod covers and it's the short time while the exhaust not fully closed and intake is starting to open.  Is that what cam overlap is and is normal?  I have always found at least a little gas in the A/C even when it's running great.  Sorry I know nothing about cams, but the air out of the carb was enough to leave gas all over my hand.  Cam is Andrews J, lifters are Velva Touch adjusted to spec, 1-1/2 turns front cyl, 1 turn on rear.

Gonna do a comp test.

[JW113]

Yes, the Andrews J has a fair amount of overlap. Probably what you're feeling.

While you're checking the timing, perhaps do a compression test also?



-JW

[96flhpi]

Yes, the Andrews J has a fair amount of overlap. Probably what you're feeling.

While you're checking the timing, perhaps do a compression test also?



-JW

I see what you did there!  Gotta borrow a light for timing but have a comp gauge. 

Comp is down from 137/135 two months ago before heads were redone to 115 front and rear now.  Could fully warmed engine then vs cold now and the fact that the carbon's been cleaned off the pistons and heads account for that.  Head came off because oil was getting in, carbon was caked in spots.

Unbelievably gonna change carbs AGAIN to see if current CV is the stumble under load issue.  Only thing left I can think of with advance is that those $8 for 10 springs are all crap, they are Taiwan after all.  Tried the ones that came with the American Prime unit - which are gold colored, but doubt they're the super stiff like in those tuning kits - made no difference. 

[96flhpi]

OK so spare CV back on, starts right up, choke works as it should, takes throttle under load, AND no high idle at least while cold.  Seems like (fingers crossed) it's good enough to get beyond the top of my driveway tomorrow to see what happens on a fully heated engine.

If I strip the plastic/rubber off the body of the first CV and let it sit a few days in a gallon of carb cleaner will it eat up the throttle shaft seals?  Something obviously got clogged while it was on the bench.  Sprayed carb cleaner through it before I put it back on but one of the internal passages must be blocked.  And anyone know where to get those seals for both a CV and a butterfly?  I swear some day I'm gonna get that butterfly to run well for more than a few weeks

Thanks again.

[76shuvlinoff]

The CV carb was one of the better things I did for my shovel.  Is the diaphragm in it ok?

[JW113]

I don't use that carb dip stuff anymore. I know it's throwing more money at the problem, but I like the cheapo ultrasonic cleaner from HF and use half water and half Pine Sol. Works amazing well.

-JW

[96flhpi]

Well the moral of this story is you get what you pay for.  It turns out the advance issue was the cheap ~ 10 for $8 springs from Mid-USA.  Kept changing springs on the same advance unit and eventually found 2 of the 10 where it was much better but not totally gone, ordered the ridiculously overpriced $25 for 2 spring set from V-Twin and high idle problem is gone completely.  Irony is the V-Twin set is of course also from Taiwan.  Definitely a different manufacturer though - the "V" that goes through the weights is more of a "U".

All other problems were my own doing - ie, not noticing I had pinched the ignition wire behind the points plate during my many advance swaps and one CV carb having its own separate issue.  It's not the diaphragm - I only have one slide that's been getting swapped and it's totally fine in the current CV.  I'm fairly sure a passage is blocked, when I spray cleaner into the little brass passages in the throat a LOT more comes out of the slow jet on the good carb then on the bad.  Guess I'll look into that ultrasonic tank.

Thanks all for the help!!

[motorplex88]

Glad you found your problem

[kd]

It's never helpful when seemingly one Problem arises and it turns into more than one issue causing it.

[JW113]

Reply #2.


Glad you figured it out.

-JW

[96flhpi]

Reply #2.


Glad you figured it out.

-JW

True but I did it without a timing light