Vacuum Leak

[Sentinel357]

So started to perform shotgun and found one of my air fuel mixture screws is stuck and I screwed up the head so the screw driver will no longer grab, lesson to be learned make sure the screw driver is a perfect fit before starting. I performed shotgun on the other three carbs and hoped for the best, put it all back together and am still having problems with only able to run with choke on. I read a lot of posts about vacuum leaks so I sprayed carb cleaner around the boots and found that when I spray the intake boots on both sides I get an increase in RPM's. No where else I spray I get the same effects. Does this sound right for a vacuum leak or am I spraying an area that would not be suspect for a vacuum leak. I plan to pull the carbs and try to remove the stuck air fuel mixture screw from the bench, if I am unsuccessful I will be sending it off to have it removed and the carbs gone through. I have uploaded a photo, I think, of the intake boot that is torn. If this is part of my problem is replacing the boot enough or do I need to also replace the clamps? Thanks for reading my long post.

 

[dannymax]

Vacuum leaks certainly can occur in the vboost butterfly area and from your post it sounds like you are picking up the signature of one.

Carefully inspect all the rubbers and replace any with cracks or brittleness, you will have to remove the intake runners to replace the boots you have indicated...there are o-rings under them, be sure to inspect them also.

No, you won't need to replace the clamps....just oil or never-seize the screw threads so they turn freely, it simplifies installation.

 

[Sentinel357]

OK thank you I ordered new boots for vboost intake and the carbs just in case. I also ordered two of the "o" ring you mentioned. Would you advise putting a little oil onto the "O"rings before re-install?
Thank you

 

[dannymax]

That's a good question....I use o-ring grease, greenish sticky stuff, but it's more to hold the o-ring in place when bolting the runner down than anything else. Don't think oil would be harmful but not sure it would hold the o-ring well enough.

 

[Sentinel357]

OK I will pick up some o ring grease. One more question please, I am concerned that when I try to back out the bolts holding the runners in place they are going to be very stubborn any advise to help prevent breaking or stripping the bolt?
Thank you again

 

[dannymax]

I've never had any trouble with them, just smack the wrench with the palm of your hand, they should loosen pretty easily.

 

[[email protected]]

Pay attention to the bolts as they come out of your intake manifolds. 2 of the 8 bolts will be shorter than the others. IIRC it is the front left and rear right bolts that are the oddballs. The short ones should have some yamabond4 (or other sealant of choice) smeared onto the threads because they pentetrate a non-pressurized oil cavity.

 

[Sentinel357]

Good to know something else to pick up at the parts store.

 

[D-Max2012]

Looking at your photo. it looks like your boot is split and separating away from the contour of the clamp. I found that my Carb boots were cracked not too long ago.. One of them looked like the Iron Giant's head..


:rofl_200:

 

[Sentinel357]

Well I ordered 8 boots. 4 for vboost and 4 for the carbs. I would hate to pull the carbs to replace the vboost boots and find that the carb boots are cracked also. If they are not cracked right now they probably will later. Better to have it and not need it and such. Of course I told the wife that I had to have all 8 or the bike will never run.