No vacuum on right front carb

[ScottXD45]

I went to Bummer's house yesterday and he helped me sync my carbs(Thank you Bummer). We weren't actually able to sync them all though because the right front carb had no vacuum on the carbtune. We evened out the other three and adjusted the idle and it runs better than before but still cuts out sometimes. I checked the diaphram and it looks good. The cylinder is still firing at least sometimes because if I pull that plug wire off the is a difference in the idle. Any suggestions on where to start looking?

[gscbertrand]

There has to be vacum on #3. Check compression on all the cylinders and don't forget to turn the throttle all the way open. If there is no vacum; have you tried a different hose from the carbtune tool? A leak down test is needed to find a compresion leak. Bent or stuck valve or spring or broken ring?

[Venturous Randy]

My first thought is you are not closing the throttle plate as much as you think you are. My second thought is you have a big leak in your YICS on that cylinder. As far as the YICS, take it all off and get some good plugs to cap the fittings with. Another thing is to take the air box off and put your hand over that carb. If it sucks in a bunch, you got vacuum.

RandyA

[ScottXD45]

I'll do a compression test next time I get time. We did switch the hoses and still didn't get a reading on that cylinder. I don't know what or where the YICS is but I'll try to look it up.

 

Thanks for the ideas.

[Bummer]

Hi Scott,

 

Glad to help - any time. It was nice meeting you and Rachael.

 

After you guys left I got to wondering if the vacuum port's even clear. I shoulda checked. Homer moment, I suppose.