Why won't idle come down

[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