Topic: 1977 cb750f2 wont reach high rpms

[jjonovic]

I currently have the engine taken apart for this bike. When i took the head off i noticed that everything had a very thick carbon covering. Making me assume that for some reason it was running rich. Before i took the engine out the bike would not run all the way up to red line. For example in  first gear i could only hit about 7500rpm it got worse with each gear 2nd 7000 3rd 6500 and so on. When it forst began doing this i took the carbs apart cleaned aveything and checked everything. Everything in them was stock and the needles were at the factory setting. When i put the cleaned carbs back on it did the same thing. I then checked to make sure my timing advance was working and it is moving freely. The bike was still doing it right before i took the engine out to replace all the leaky seals. At high rpms the bike just kinda gurgles out and wont rev and higher in first sometimes u can force it but any other gear u cant. I am out of ideas and am open to any advice thanks. 

[TwoTired]

You had these problems with stock exhaust and intake filtration?

Did you read your spark plugs to determine combustion conditions when the problem occurred?

How confident are you that the ignition components are in good working order and adjusted correctly?

Any tune up history?

Did you verify your slow and main jets were correctly numbered and not drilled to a larger size?

Did you check the intake runners for vacuum leaks?

Cheers,

[750goes]

Just a thought,

when you cleaned the carbies, did you limit the maximum throttle opening position this could be a reason why it won't rev past 7-7500.

[eldar]

lots of carbon generally means rich operation. Fuel seems to usually cause an issue like this. run it as wide open as you can and kill the engine without allowing rpm to drop. then look at your plugs. If they are realy sooty, then you are likely too rich. try dropping you needles 1 notch.

[Philly550K1]

"point float" should be ruled out -- (like lloyd implied), make sure there is good spring tension on the points and that they are clean, dressed, and groomed....  -jc

[mutters]

 And please keep notes on any adjustments, or changes, and the correseponding results for future reference purposes
 for all our sakes