Do I need to synch my carbs?

[murraymark354]

Hey guys I'm new here so be gentle haha ive been having poor thorttle response while riding lately. Mostly in the 1_3k range and from 5.5k and above. Pulled my plugs and cylindes one and two were a nice brown/tan. Cylinders 3 and 4 were black. I had bench synched my carbs a while back. All my air/fuel mixture screws are 2.5 out. So my question is my poor throttle response/ miscolored plugs from carbs being out of synch?

Its an 82 cb750 custom

 

[amc49]

Short answer...........a little.

Compression test to determine the basic engine condition to see if you are wasting your time and money. Need 170 or close.

Set the valves carefully to .005" minimum. MANY perceived carb issues come from that and most then go after the wrong thing. These engines are well known for closing up valve clearance to then run like crap. Your 5500 and up issue is a perfect description of it.

 

[murraymark354]

I did a compression test. Cylinder #1 was 120, cylinder #2 was 90, cylinder #3 was 120 and cylinder #4 was 120. Im not trying to knock you but is 170 correct? That seems kinda high. But how would I go about adjusting the valves since there's no adjuster? Would I have to take the buckets off and shim it?

 

[amc49]

Now you know why I told you to test it. 170 is the service manual figure and only 9/1 compression. They will run fine down to 140 and maybe even 130 but consider any cylinder less than 100 as pretty much a dead one. Do multiple tests since many compression gauges are crap tools. I always run at least 3 to be sure of where I'm at.

The buckets have shims snapped into the top of them, you change shim. You can do it without removing buckets.