Not just another carb sync question!

[apox]

Ok assume your carbs are synced nicely.. Even vacuum on your homemade manometer, you then decide to adjust your idle stop screw for 1200rpm, your carbs then fall out of sync.. What could cause this? Or is it really not much to worry about, just resync at 1200?

 

[retiredgentleman]

The manometer is extremely sensitive, so yes it moves alot. Don't be concerned, just set it at 1200 rpm and you're done.

 

[apox]

Perfect thanks

 

[grizld1]

Sorry, I can't agree with that without more information. Apox, you didn't mention what rpm you synched at or how much tracking difference the manometer shows between the two cylinders. A large difference could indicate a lot of things--a partial obstruction of the pilot nozzles in the spigot in one of the carbs, a vacuum leak, or a marginal valve, to name a few.

 

[apox]

It was around 1050-1100 or something before I turned it to around 1200. I only have the stocker tachometer so it's as good as it gets. Carbs were just completely rebuilt, every single little piece and hole cleaned or replaced. Originally one cylinder wasn't firing, rebuilding the carbs had it running no problem again. The only plausible things I believe could be a vacuum leak, as I'm running stock boots and diaphragms, boots are still soft though, but a bit of age and beat up a bit.

 

[grizld1]

I think RG is probably right here; the throttle shaft linkage on the OEM carbs isn't exactly a precision item, and that small a difference in rpm shouldn't make a big difference in engine vacuum, etc. Back to the other question; how much difference did the manometer show? If it's minor, don't be concerned.

 

[apox]

Like gentleman said it's very sensitive, it doesn't change drastically but it just slowly climbs and climbs even after your done changing it. I havnt waited too too long but I'm sure if you left it for a while it would probably climb pretty far.

 

[weekendrider]

apox do you have some sort of reducer in your monometer lines?
It calms things down.

 

[apox]

No unfortunately not, first bike, no spare jets lying around. Used ATF.