Carbs WAY out of sync, can't get them in line...

Hi all!

I just finished building a set of vacuum gauges to do a dynamic sync on my 1986 VFR750.

The front two carburetors are matched at 5 in. HG, but the rear two are running at 10 in. HG (The manual says they should all be within 1.6 in. HG of each other). It seems I CAN NOT get the front pair and back pair in line, no matter how I adjust the screws. Once I get the carb adjustment screw dialed in, the idle screw lifts entirely off. I believe something is bent or otherwise out of wack with the rod connecting the front carbs and the rear.

I fully understand that the PROPER thing to do is to remove the carbs and get everything in line. However the weather is just too compelling! I want to ride, dammit. =)

The question I have is: Can running the carbs so out of sync do any harm? Like is this something that MUST be remedied, or will it just make the bike run a little off? If I can leave it for now I'll have them looked at by someone with a little more experience when the season's over.

Thanks!!!

 

just get them as close as you can, then ride it. It won't be ideal but you can fix it when the weather is bad. There are lots of little springs that go between the adjustment screws and the linkages--if the carbs were ever dismantled then those springs are likely missing and it won't synch correctly without them...

 

With a normal, properly-running bike, there is no need to turn any synch screw more than 1/8 to 1/4 turn for adjustment. The sequence of screw adjustment is key to good results, outlined in FSM.

Once the screws get too far off, you'd best remove the carbs from the bike and start over with a good bench synch.

Working upside-down and backwards where you can't see well and your hands are getting burned isn't much fun.

No harm done, but you'll miss the pleasure of a smooth, even idle, and possibly get some surging at low throttle openings.