CB77 has no power in 4th gear

[sjkowal]

I have a '65 CB77 with the transmission x'ed. The first, second, and third gear seem to work fine but when I get into fourth the bike has no power. In fourth I can maintain my speed but it won't increase. If the RPMs start to decrease then I'll usually have to downshift back to third. So the RPMs never increase in fourth. This seems to rule out any issue with the clutch slipping from what I understand. I'm running the stock gearing on the front 15T and rear 30T sprockets. I've tried pushing the RPMs higher in third but switching to fourth has the same results. Anyone have any idea what the issue might be? Could it be a problem with my carbs?

[LOUD MOUSE]

Have you checked the compression and timing?. ....................lm

I have a '65 CB77 with the transmission x'ed. The first, second, and third gear seem to work fine but when I get into fourth the bike has no power. In fourth I can maintain my speed but it won't increase. If the RPMs start to decrease then I'll usually have to downshift back to third. So the RPMs never increase in fourth. This seems to rule out any issue with the clutch slipping from what I understand. I'm running the stock gearing on the front 15T and rear 30T sprockets. I've tried pushing the RPMs higher in third but switching to fourth has the same results. Anyone have any idea what the issue might be? Could it be a problem with my carbs?

[G-Man]

The bike has to work harder in 4th gear so this is where problems with the condition of the engine will show up.

You need to give the engine a check over, including as LM says timing and compression.

Check also carb settings / synchronisation
Air filters
Valve clearance
Also check if either of the brakes are binding

G

I have a '65 CB77 with the transmission x'ed. The first, second, and third gear seem to work fine but when I get into fourth the bike has no power. In fourth I can maintain my speed but it won't increase. If the RPMs start to decrease then I'll usually have to downshift back to third. So the RPMs never increase in fourth. This seems to rule out any issue with the clutch slipping from what I understand. I'm running the stock gearing on the front 15T and rear 30T sprockets. I've tried pushing the RPMs higher in third but switching to fourth has the same results. Anyone have any idea what the issue might be? Could it be a problem with my carbs?