Engine power surge

[81cb750f]

I have an 81CB750F and have owned it since 1986. I have never encountered the following until recently. When cruising at about 5,000 rpm, occasionally there will be a sudden power surge while the throttle is being held steady, almost like I've twisted the throttle. Except that I haven't. And it is only for a fraction of a second, then continues to ride smoothly. Anyone have any ideas on what this could be? So far I've checked timing, cam chain tension, and plugs. I haven't checked the sync on the carbs but had done that last year and this all started late last year.

 

[brettp]

When was the last time you did a valve job on your bike? I think, but could be wrong, right around 5k is where the power band starts. And those valves need to be kept up.
Could also be a lean condition like an air leak? Checked for that?

 

[81cb750f]

When was the last time you did a valve job on your bike? I think, but could be wrong, right around 5k is where the power band starts. And those valves need to be kept up.
Could also be a lean condition like an air leak? Checked for that?

Forgot to mention, valve clearances have just been checked as well and are all within spec.
But a lean condition, ya, could be. Any suggestions on where to look? I replaced the the intake rubber boots last year.

 

[brettp]

The only location I can think of are the boots on both sides of the carb.
Is it possible the clutch is slipping?

 

[81cb750f]

The only location I can think of are the boots on both sides of the carb.
Is it possible the clutch is slipping?

I'll check the boots.
Don't think clutch is slipping. I can still launch the bike fairly hard from standstill without slippage.

 

[81cb750f]

The only location I can think of are the boots on both sides of the carb.
Is it possible the clutch is slipping?

I'll check the boots.
Don't think clutch is slipping. I can still launch the bike fairly hard from standstill without slippage.

boots seem fine. sprayed water on them at idle and above idle with no change to engine speed. will have to look elsewhere I guess. maybe carbs out of sync.

 

[brettp]

boots seem fine. sprayed water on them at idle and above idle with no change to engine speed. will have to look elsewhere I guess. maybe carbs out of sync.

That could absolutely be a potential