Carb Sync Issues/Vacuum trouble.

Hello again. It is finally warm enough to run my bike in Alberta! The bike would not idle without the choke but managed to adjust the idle screw and now it idles at approx 1000rpm. However, I tried to sync the carbs but am not getting a reading on my Carbtune on cylinder 4 - no vacuum reading at all. All the other cylinders register. Can I assume that there is a vacuum leak somewhere?

Also, how do you folks get in to adjust the sync screws? Maybe my hand is too big! I tried a socket, 7mm wrench, and small screwdriver and it is almost impossible to get in there. The single screw between the front two cylinders is the worst and almost impossible to access. Tried a wrench, screwdriver and even a right angle screwdriver without luck so far.

Any help would be greatly appreciated! Thank you so much, Doug

 

This is my tool of choice for carb syncing, there are more expensive ones that may be better, but this seems like best bang for the buck. Make sure the screws aren't super tightened up or anything when you have it off for rebuild. This thing can't put a ton of torque on anything. You hold the black part steady, turn the handle, and it moves the flat blade screwdriver at the end.

MOTION PRO Pilot Screw Adjuster Tool 08-0119


https://bulletproofdesigns.com/motion-pro-pilot-screw-adjuster-tool-08-0119/

 

Did a vacuum line perhaps decide it was it's time to crack and fail? What bike are we talking about?

 

This looks great - thanks. I have tried sockets, swivel sockets, screwdriver bits, right angle screw drivers, small screw drivers and a few other things and nothing is easy. My hands are too big to get in there.

 

I discovered later today that the cylinders do register on the Carbtune but not until the throttle is twisted. One cylinder is reving normally but the others not enough to register. There must be a vacuum leak somewhere. Perhaps something else? I did managed to turn two of the sync screws but it didn't make a difference. Strange because I bench synced the carbs before I installed them. Not sure what is going on here. I may have to remove the carbs (yuck) and have a look.