A simple question for all you experts!
Harley EvoDiscuss A simple question for all you experts! in the Motorcycles forums; As you know I have been getting this 95 FLHTC running-right and fixing all it's issues. I ran into something strange...
I decided to pull the plugs for the second ...
As you know I have been getting this 95 FLHTC running-right and fixing all it's issues. I ran into something strange...
I decided to pull the plugs for the second time since getting the bike. The first time I pulled them right after I got the bike without even riding it. They looked pretty rich but decided to run them.
Second time after about a hundred miles of riding, pulled the plugs... They were gray. In my opinion mixture was pretty good. This is where it is interesting. I decided to check the idle mixture screw. It was turned all the way in! The bike was still running. At idle a little stumble or so but still running! So with a little research I found that this CV carb should have the screw 2-3 turns out as a rough setting.
I cranked it out 2.5 turns. Actually the bike seems to be running better now. Is this weird or standard stuff? Further, when I had the ignition switch recall done, the HD tech that it was a pretty nice bike but it needed new intake manifold seals and probably the carb to intake seal changed out. He said the carb might need cleaning and a rebuild.
Is there air leaking into the intake which would negate the idle mixture? Is this telling me the idle jet is too big? I know the main jet or needle have nothing to do with the idle.
Already had the carb off to readjust the float so doing all the intake seals is not going to be a problem. It's just weird that it would not stall with the needle all the way in. And it putters along at 950-1000 at idle. When I rebuild the carb I will put one of the Harley-performance.com stage one kits in it. Oh, it has a Ness big sucker filter on it and some unknown after market pipes.
You guys know all this stuff. I don't. If it does not have wings or a jet engine.... Thanks bro's and sisters!
Your HD tech was on the scent. To check for leaks in your intake system start the bike and get it warmed up and idling. Then spray WD40 on the suspected joints. If your idle changes when you do this you have an intake leak. Easy enough to fix. If this little test doesn't show leaks then your carb is the next place to look for problems.
Fair advice on the intake leak, but even spraying WD-40, BrakeKleen, or even H2O might not reveal a small discrepancy in the intake connections. (I HATE that term, "intake leak!) The best method is to fashion a block-off plate for the manifold face, and introduce 10-15psi air pressure. Then spray a soapy water solution on the connections and look for bubbles. This will reveal even the smallest of leaks. (Engine must be rotated so both intake valves are closed, of course.)
Here's the setup I fabicated for my panhead, you can do the same for any bike.
If there is an Intake Leak it will contaminate Not only the Idle A/F mix but ALL circuits of the A/F mix..
If you pulled the plugs after just idling in to the garage then that grey color is a snap-shot of the Idle A/F mix..
Sounds like a good color but there is apparently some other issue..
With the idle A/F mix screw bottomed out (all the way in) I'm thinking of 2 things..
Possibly somebody has forcibly bottomed out that screw and deformed the seat allowing enough air to get by to idle..
And/Or the idle speed is just high enough to be barely in the Low-spd circuit..
You might lower the idle speed Waaaaay down and then turn the A/F screw all the way in again,,,, see what happens..
Spray those seals and Carb "booty" OR just change them anyway as you planned..
Any of those spray chemicals will work,, I prefer CarbCleaner..
Very interesting way of checking for intake leaks & accurate I'm sure but kinda over-kill for such a simple test..
I've never done that but I'd imagine the pressurized air will leak up through the Valve guides, seals,, etc..
__________________ "Fill your hands you son of a bitch"
Rooster Cogburn
sounds like to me that the carb needs a good going over, taking all the jets out, needle and seat and choke circuit and giving a good cleaning, spraying through all of the passages and making sure nothing is clogged. also check to make sure the air isn't getting by at the butterfly and butterfly shaft, these wear over time and can suck air so sparay this area as well when looking for the leaks.
I ran it for about 50 miles today. Within one minute of arriving home I had the rear plug out. It is pretty much gray even with the idle backed out about two and a half turns. Given the hack job repairs I have found it would not surprise me that they cranked it down past it's limit. Frisco I played with it a little more after reading your post. I did get the idle to drop when turning in the screw enough to stall. For now, I just brought it back out a little to keep it running until I rip off the intake and carb in a couple of weeks. It seems to be running pretty good now. Now it has a slight burble on decel which it didn't have before I was playing with it today. Boy this thing has a lot of grunt... My Valkyrie was like a sewing machine gone wild but this is a whole different animal.
My thought is that if I had wanted another sewing machine I would have bought a Singer. I am having a great time learning and listening to you guys!
That is a beautiful piece of work ya got there BigIncher. There is something to be said for old school! We sorta do that same thing on recip aircraft. I don't have access to compressor... I need a bigger shop! Thanks. I am going to keep this photo for reference. When I have the carb off I will build a template from it.
Very interesting way of checking for intake leaks & accurate I'm sure but kinda over-kill for such a simple test..
I've never done that but I'd imagine the pressurized air will leak up through the Valve guides, seals,, etc..
If 10psi leaks past the valves, guides, and seals, you've got a problem. The test is for the intake manifold, nothing more. Your chemical spray may work well on huge obvious leaks, but maybe you've never seen a small leak on an O-ring or compliance fitting intake manifold.......
Spray away, and think to yourself all is well..!
That is a beautiful piece of work ya got there BigIncher. There is something to be said for old school! We sorta do that same thing on recip aircraft. I don't have access to compressor... I need a bigger shop! Thanks. I am going to keep this photo for reference. When I have the carb off I will build a template from it.
Kempo
Thank-you, Kempo. Contrary to what the so-called modern-day experts say about spraying "chemicals" to find intake leaks, this is really the only way to be absolutely sure to find even the smallest of leaks. It's not overkill, and it's not even hard to do. And you don't really need an air compressor, you just want to introduce 10-15psi. You can probably do that with a hand pump.
Actually, if it works at all it's like killing fleas with a .45..
The valve stem In the valve guide was Never meant to be an Air Tight fit nor is the valve stem seal.. 10-15 lbs. of pressured air will likely sneak through even though it might not matter..
Plus the fact that neither the "plumbers fittings"--Nut, Nipple, & brass seals,,,,, O-rings, Rubber-bands or Evo tapered seals were intended to Hold-In Pressure,, instead,,,, only seal against the atmosphere..
I realize that since You said it and You made the tester You think it is the VERY Best and all should be convinced BUT----the spray will catch even the smallest leaks..
Tell ya what---- find a manual, website, forum, Q & A, tech article,,,, etc etc etc that says that contraption OR one like it is THE way to go..
I've never heard or seen any advice but spray..
My contrary-ness should Not dis-courage others from trying it but, your statement, meant to convey that your way is the only way, immediately needs rebuttal..
Hi Kempo
You're doing fine..
When things aren't Pressing you can do them at your own leisure..
__________________ "Fill your hands you son of a bitch"
Rooster Cogburn
Last edited by frisco-rigid; 10-20-2009 at 04:15 AM.
A simple question for all you experts! 
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