I have an intake manifold leak that I cannot seem to get rid of. The PO had an idle jet stamped with a #20 on it which appears to be exactly the same size as a #50. In my opinion, that's way to rich for a stock 80" with a stage one. Funny thing was the plugs were the perfect color after thousands of miles. I replaced it with a #45 and was getting some pinging at low revs when I would give a little too much throttle. I then put a #46 in with similar results. My next thought was that the bike must be running lean to get the pinging which would suggest a vacuum leak since those jets should be right on for my setup. I sprayed brake cleaner around and the revs drop when I hit the intake manifold near either cylinder. Pulled the carb and manifold and the o-rings looked fine. Bought new ones from the stealer anyways. Still have the leak. I installed the intake manifold the way I always have which is the same as the manual states. Install the o-rings and manifold but don't tighten the bolts. Install the carb and align everything, then tighten the bolts.

Never had this issue before. Anyone know any tricks for getting a good seal?

 

Tighten one side a little, than the other a little and repeat while checking the fit as you go. When you put the carb on did you put the seal on the manifold and push the carb into it? I have seen where people have put it on the carb and pushed it all on at once. If the seal is kinked in the manifold it would do what you are saying. It can be a pain if it isn't just right.

 

Always do it that way.

No, the gasket goes on the manifold and then the carb gets pushed into it. It's really difficult to get it right doing it the other way. Also, I don't have a leak between the carb and the manifold. The leak is between the manifold and both cylinders.

 

Sorry guy, it was all I could think of at the time.

 

Don't apologize. No problem at all. All suggestions in the forum are helpful even if it turns out that they've already been tried.

 

I did have to walk away from mine and come back to it when I put an S&S on it. Mine is a 93 also.

 

I was rebuilding top end some two years ago. Bought new manifold seals, installed them. Found an intake leak. I`ve tried everything, then I took it apart and installed old seals with a bit of silicone on each seal. No problems since then.

 

Sorry to necro-post, but I just wanted to point out a post that was very helpful to me.

I had a pinging issue that became apparent after installing a new, quieter exhaust. I thought maybe it was timing, so I started searching back through older posts for ones related to timing. Specifically I was looking for the info about which way to turn the timing plate to advance or retard the timing(counter clockwise to retard, btw) and then I came accross this thread.

This thread described the pinging issue exactly the same as I was experiencing, so I fired up the bike on the stand with the choke on and sprayed some chemtool at the intake to head joint and the idle stumbled with both cylinders. It didn't stumble when I hit the carb to manifold joint.

Using this info, I figured I had a manifold leak. I pulled the bags, pulled the seat and unscrewed the rear of the tank to swing it up, then I removed the horn assembly to get at the manifold bolts. I pulled the carb out as one solid unit and pulled the old o-rings out of the manifold rings. They didn't look bad, but were pretty squished. I guess in my haste to put everything back together after replacing the head gaskets, I overlooked the manifold rings.

I cleaned the surfaces, put in the new rubber seals that came with my top end gasket kit, then put everything back together the way described above. I put a stud into the right side front cylinder mount to keep the carb aligned, then lined up the manifold rings and started all 4 screws to finger tight. Next I went 1/2 turn at a time on each screw, moving clockwise until all 4 were tight(front lower, front upper, rear upper, rear lower). I finished attaching the carb, hooked up the fuel line, fired her up with the choke on and tried the chemtool again. This time the idle did not change at all. I guess I fixed the leak! I put her all back together and was going to go for a ride to test it out, and it started downpouring outside! Figures...


I guess I'll wait a bit for it to quit, then see how she rides now. I'm guessing with no leak now and a big leak before, she will probably run a lot better...

 

there is an alignment tool that harley sells....and it's well worth it, to me

i believe it's part #40054-01.... only 20.00.... but everything will be nice and lined up

when i did it, i lightly coated the edges of rubber with dialectric grease so that nothing would fold....and when i tell you 'lightly'...i mean, LIGHTLY

 

I have been through this problem several times, Develop a leak install new seals few miles later leak is back so i tried the blue silicon seal and they have a lip that go between the manifold and head which keeps the manifold and seals in place several hundred miles later still good. Check them out part # 401-372 from jp