SOHC.co.uk Forums > CB750

Flat spot 65-70mph

(1/4) > >>

leonardo269:
Hi,
    I have noticed that my K7 has a flat spot at about 65-70mph. If held at a steady 65 it goes into a cycle of surges followed by loss of power. At all other times it runs perfect.

I have got electronic ignition, K&N re-useable air filter and Motad 4 into one exhaust. Everything else is bog standard.
I have a feeling that the carbs are running the original jets.

Has anyone else got a similar set up to this?  

Any advice appeciated.

Cheers,

Ray

uk_kev:
could this be something to do with the auto advance unit?

JonnyB:
Does sound like ignition timing at high revs, What rpm are you doing 65 at, and if you slightly over rev 4th do you get similar fades in power.

Got to admit My F is doing something similar at about the same speed, and I have the old points and condensor setup. I've settled for just doing the speed limit :P

leonardo269:
Hi,
    The electronic ignition is by Newtronic and it replaces both the points and advance assembly, so there shouldn't be a problem.

I will check the timing again to make sure that it is all set up correctly.

Cheers,

Ray

uk_kev:
If it is all set correctly then I would think it is the jetting due to the filter change more than the exhaust? I wonder do the sport version with the single pipe use the same jetting as the four pipe models? if not then that may be a starting point.

Navigation

[0] Message Index

[#] Next page