Detecting an air leak

emto · Post by **emto** » Sun May 31, 2009 12:43 pm

I suspect I've got an air leak after fitting new carb rubbers. I've heard there's a way of finding out which one is leaking by spraying WD40 down the velocity stacks, but can anyone let me know if this is correct and if so, how do I go about it?

Thanks

Post by **CMSMJ1** » Sun May 31, 2009 1:09 pm

No - don't spray WD40 into the stacks.

get something like carb/brake cleaner that will just burn. Spray it near the rubber - if the revs pick up it has sucked some in via your air leak. Simple as that really..you are basically bypassing the carbs.

dave_c24 · Post by **dave_c24** » Mon Jun 01, 2009 7:03 am

i was using wd40 type spray, didnt pick up my leak, used carb cleaner and found it but now cant cure it.

new rubbers tightened clips right up then it moved from rear to front carb????

any ideas!

cheers dave

emto · Post by **emto** » Mon Jun 01, 2009 12:14 pm

I pulled out the carbs again without using the carb spray ( as i wasn't sure if you sprayed the outside of the rubbers with everything in tact, or what) but I did find that the new rubbers had worked loose, must be something to do with bedding in. However, it didn't cure my problem either. Now I'm wondering if the additional needle shims might be a cause. If so, would opening the pilot screws further lean out the mix and stop the popping/missing, or do you go in? they're currently set at 2.25 out. Or do I just remove the shims and forfeit the extra midrange?

Any help appreciated.

dave_c24 · Post by **dave_c24** » Tue Jun 02, 2009 6:54 am

emto wrote:I pulled out the carbs again without using the carb spray ( as i wasn't sure if you sprayed the outside of the rubbers with everything in tact, or what) but I did find that the new rubbers had worked loose, must be something to do with bedding in. However, it didn't cure my problem either. Now I'm wondering if the additional needle shims might be a cause. If so, would opening the pilot screws further lean out the mix and stop the popping/missing, or do you go in? they're currently set at 2.25 out. Or do I just remove the shims and forfeit the extra midrange?

Any help appreciated.

i took the carbs off last night and to check seating and have brought them into work to strip and clean.

i did notice my new inlet rubbers have split inside around the sealing grove, not all the way through but would this cause a leak as it would stop them sealing properly?

might be worth a look? they wernt very noticeble until i distorted the rubbers all bar 1 had done it???

cheers dave

Detecting an air leak

Detecting an air leak

Re: Detecting an air leak

Re: Detecting an air leak

Re: Detecting an air leak

Re: Detecting an air leak