intake manifold carb seal

[sashkar2000]

Hi guys,

After taking the carb on/off about a dozen times the rubber inside the intake manifold that creates a seal with the carb has gotten flat and i believe is causing an air leak.

This doesn't appear to be a replaceable part and replacing the whole manifold seems overkill.

Do you think i can make a seal with silicon? Which permatex product would work? The red and blue have a note saying they degrade with gas. The white one is gas resistant but can't handle high temperatures.

thanks in advance.

[adidasguy]

You get a good seal when you tighten the metal bands. No need to use silicone and I wouldn't do that.
Are you tightening the metal bands when on, and loosening them when you remove and install the carbs?

[radodrill]

You can buy/replace just the intake boots and O-rings for ~$80 from BikeBandit ($34/boot and $5/O-ring); listed under engine parts.

That said, Why do you think they're leaking?  If you spray WD-40 on at the boots (with the engine running) and the engune speed doesn't change, then you don't have a leak.

[sashkar2000]

Yeah I tighten all the metal clamps and now there's not much resistance in them and i easily tighten them all the way in.

I know i have a leak because the rpms suddenly jump and i end up fiddling with the idle screw during the warmup procedure or it idles at 4k. and also the local shop gave me the same diagnoses. i haven't done the wd40 test yet to determine where the leak is. just assumed it was from there cause the rubber is visually depressed (i probably put the carbs in with too much force initially).

i have to take the carbs off yet again to clean a clogged pilot jet, so wanted to fix the leak problem as well...

[adidasguy]

You must determine the source of the air leak before you blindly start messing with things. You might be over tightening the clamps. Snug is good enough to seal them. Too tight and you can damage the carb boots - they are just hard rubber.

Common sources of air leaks:
1. Missing o-ring on carb caps (except 2001-2002)
2. Intakes: could be where carbs go in OR the seal between the carb boots and the cylinder head
3. Leak from air box to carbs
4. Missing air box drain hose
5. Missing cap-off on one of the carbs (the other one goes to the petcock.)

And other issues to  check:
1. Proper valve clearances (err on the side of too much clearance)
2. Loose exhaust

Jets may be an issue. If clogged, engine will run slow. When it runs fast, it sucks harder and will suck in more gas keeping it running fast. Drop the RPM,s by slipping the clutch and the suck goes away, it sucks less fuel through dirty passages and RPM,s now drop really low (buddha, bigrich, gsjack - does this sound reasonable?) Kind of like a schmidt trigger in electronics?