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Discussion Starter · #1 ·
I recently replaced the starter in my R1, which required the removal of the throttle bodies. Everything went well with the exception of starting it up after putting everything back together. It no has a miss at idle and off idle throttle (and stumbles bad with load below ~3500 rpm), which I have confirmed (via carb cleaner) to be a vacuum leak around the seals between the throttle bodies and the head.

I figured it was due to the age of the seals (heat / aging etc making them too hard to seal well anymore), so I purchased new seals and clamps from Yamaha.

I installed the new seals and clamps expecting my troubles to be over, but no luck. There is still a slight leak (confirmed again via carb cleaner). I've tried everything I can think of, Ive uninstalled and reinstalled the seals and clamps ~10 times and no luck getting them to seal up 100%

I know for certain the seals are on the correct cylinder, positioned correctly etc (they can only go on one way). I havent over tighted them (the clamps have spacers built into them to prevent this).

I'm really at the end of my rope with this now. I've even resorted to using black RTV sealer - which helped but still has a small vacuum leak, since you cant use very much without it squishing out and getting into the intake.... confirmed again with carb cleaner that the vacuum leak still exists.

I've been extra meticulous cleaning the seal, the head, and the throttle bodies, test fitting everything, being very careful when tighting down the clamps etc - but somehow this thing will still not seal correctly. Visually everything looks like its tight / seated in the seal correctly... but still leaks.

Has anyone encountered this? How did you fix it? Any suggestions? I even gave a set of silicon hose + T-clamps (like you would use on turbo pressure side tubing) a shot but wasnt able to get those to work any better either. I'm not sure what else to do at this point. I've never had my ass kicked by something so trivial like this before.....
 

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Discussion Starter · #3 ·
Well nothing I have tried seems to work. It seems no matter what I do that there is a slight vacuum leak.

I've tried 2 new sets of joints, ive tried RTV, ive tried 3m weather strip adhesive (gorilla snot), i've tried everything. No matter what, there is enough of a vacuum leak to make it miss at idle and < 2500 rpm.

Found a complete set of Throttle bodies on ebay for $100 shipped, that include the TBs, TPSs, injectors, vacuum lines, everything. Hopefully that solves my problem. I still think its a leak around the joints, but it could possibly be something else.....

I'm beyond frustrated with it at this point. Hopefully this new set of TBs / injectors etc resolves it.
 

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Discussion Starter · #6 ·
Mine ended up being a combination of things. Like stated above I bought all new seals for the throttle bodies, new throttle bodies etc and it still acted up. I was certain it was a vacuum leak but it wasnt.

I ended up figuring it out my stator was acting up (replaced it), but I also had a cam position sensor cable that was nicked / a little chewed up by my fans. I dont think it was completely severed but it was bad enough I didnt trust it. Replaced stator and cam position sensor (to replace the nicked cable) and everything was good again.

It sure acted like a vacuum leak - and I thought it was since the problem started after removing the throttle bodies to replace the starter.... but I think most of it was from the stator.
 

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Well nothing I have tried seems to work. It seems no matter what I do that there is a slight vacuum leak.

I've tried 2 new sets of joints, ive tried RTV, ive tried 3m weather strip adhesive (gorilla snot), i've tried everything. No matter what, there is enough of a vacuum leak to make it miss at idle and < 2500 rpm.

Found a complete set of Throttle bodies on ebay for $100 shipped, that include the TBs, TPSs, injectors, vacuum lines, everything. Hopefully that solves my problem. I still think its a leak around the joints, but it could possibly be something else.....

I'm beyond frustrated with it at this point. Hopefully this new set of TBs / injectors etc resolves it.
Did you ever figure it out?
 
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