carb pressure question

[ericfox]

I just rebuilt the carbs on my 1995 750slt. All carbs hold pressure except for one... it is leaking air on the fuel line side of the carb. I put grease on the rubber piece that is supposed to seal that side of the carb and now it holds pressure fine. Is this a good solution or only a temporary one?? another idea i had was using gasket maker from the auto parts store and putting it around the perimeter of that side of the carb. I got the rebuild kit from sbt... perhaps the kits rubber piece is not quite as thick as the oem part....

[surveyguy]

Re: carb pressure question

are you talking about the atmosphere cover? the one with the pin-hole and the four screws? or are you talking about where the carb mounts to the manifold?

[ericfox]

Re: carb pressure question

it is on the side that does not contain the diaphram. hope that helps

[surveyguy]

Re: carb pressure question

Oh, I re-read. Leaking near the fuel rail. Have you pinpointed it? You could spray (after removing grease) carb cleaner or ? along it to see when the engine revs to find the leak. Leaks are not good. Your solution could come off at any time.

[ericfox]

Re: carb pressure question

it was leaking all around pretty much the whole perimeter on that side..... so what should i do? is a home-made gasket using a good gasket maker a good solution?? the guy at the shop told me to put some grease around the rubber piece and that would seal it. I put the grease on and that worked, but it just does not seem like a PERMANENT solution to the problem...... by the way, I have tried re-positioning the rubber piece several times to fix it and even replaced it with a new one from SBT..... SAME PROBLEM HAPPENED! PLEASE HELP!!!!!!!

[Technical Support]

Re: carb pressure question

No, gasket maker or grease is not the answer and will cause problems inside the carb. Most likely you have a scratched or warped plate or carb surface. Try switching the cover with one of the other carbs to narrow the problem down. There is no variance in the gaskets, that's not an issue. Are you sure you're tightening the screws fully? They should REALLY be torqued down - as hard as you can get them with a large screwdriver - don't be afraid, you can't hurt them!

[surveyguy]

Re: carb pressure question

yup-yup, I 100% agree with tech here. I understand your problem now. Makes me wonder if something got hot on you and warped something. Good luck, and as a work-around, besides what tech said, if you must use 'grease', use a gasket making silacone that works with rubber. (grease???)

[ericfox]

Re: carb pressure question

thanks! will give that a try.... if the fuel piece is warped, i wonder if i have to buy a new one? (any ideas where?) or if possible somehow flatten out the surface using some kind of file or something of that sort.

[surveyguy]

Re: carb pressure question

i can't imagine they would be so bad that you would have to have them resurfaced. Well, I can, but do you know why these would be warped? I would look for obvious signs of warpage or burrs, use some good gaskets and sealant, and as Tech says, tighten those puppies down good (don't really want much gasket goop floating around in there).

[ericfox]

Re: carb pressure question

Soooo....this is how my problem was fixed. This sounds like a real fluke from the factory who makes the carb rebuild kits. It ended up that the small lip on the little filter that goes inside the carb was too thick. When you put the 2 pieces of the carb back together the top piece would sit on the lip. This made it so that when you screwed the whole thing back together that it would not make a complete seal on the rubber gasket. I used a metal file and filed off a fraction of a millimeter off of the lip of the filter and ==> BAM perfect seal! It holds pressure 100% now. Thanks for all the replies still... who knew it could be something like that though... has to be a fluke. hope this helps someone out someday

[surveyguy]

Re: carb pressure question

does sound like a fluke, good investigating!! Did you rebuild all carbs, and only found that one? I'm wondering if maybe it was the wrong filter.

At this point, who cares, right? You're cruisin' again!!

[ericfox]

Re: carb pressure question

I rebuilt all the carbs. I have not done anything with the jets, but dont know if its really necessary. The popoff pressure is perfect in all 3 and they all hold a vacuum perfectly as well. Should I check the jets? or just stick it back on and go.....

[surveyguy]

Re: carb pressure question

I've passed on this. If you've replaced all parts that are in the kit, cleared all passageways, replaced filter, adjusted the air mixture screws for factory settings, I say you're good-to-go. Thing is, when you're in there, it's a lot of work just to get back in there, but if it was ok before, your jets or seats should be fine as long as they're not marred up by over tightening.