1976 KZ 400 Power Loss

The most annoying part about my problem is the fact that the bike starts and runs fine. However, if I get out on the road and shift up through the gears, at about 45 mph it seems to lose power. If I start downshifting it will continue to lose power till I finally pull the clutch and stop, at which time the bike is idleing nicely. If I start out again I get a similar scenario. Ive done everything that I can think of. No compression problems, new points/cond, new plugs, new coil, clean carbs set and balanced properly...etc. Im beginning to think it might not be a problem of losing power but instead power being lost/starved off behind the engine. My dad mentioned possibly a bearing going out/tranny problem?? Has anyone seen this sort of problem? Ive about reached the end of my chain with this thing and would really apreciate some help. Thanks a lot! CK~

There are so many components to the bike, it's hard to focus on one thing in a situation like that.

However, two main things come to mind when I think about gradual loss of power at speed: timing advance and carbs. Remember that it isn't the speed that matters, but the RPMs.

Around 3000 RPMs is where the timing advancer is in full advance. It is also around there where the carbs use the pilot system less and start to use the main system.

For grins, you could try going up high in RPMs in a lower gear to see if it still happens. Otherwise, take a look into those two things, as well as others...