Bike cutting out at higher speeds. PROBLEM FOUND!

[1979Honda]

I've had my 1979 honda cb750 for about 3 years now and couldn't find out why it was cutting out at higher RPMs and higher speeds. I had the carbs sync'ed and it helped some but still wasn't running too good. I figured its probably the carbs need cleaned out. But, wanted to try other things before tearing the carbs off. Well, I ended up pulling the seat and tank off and took the spark plug wires off the coils. And found the problem! There was so much corrosion in there that they wern't getting a good spark! I cleaned them out and snipped a little off the spark plug wires and put them back in. And the bike runs awesome now! ALOT more power and it WILL finally rev up passed 7.5 RPMs! For some reason though It still wont go over 80 mph without feeling like its hesitating. Someone switched the motor to a 900 on it. So, i'm sure it will go over 80 ! I pulled the petcock off and cleaned it too. It wasn't too bad. Also, I put a new battery in it and for some reason its not keeping a charge now. I can only ride maybe 30 to 40 miles and have to recharge it. So, i'm not sure if that has anything to do with it or not. Gonna make another post on the charging system and see if there is an easy way to check the stator and regulator/rectifier before purchasing both.

Anyways, just wanted to let people know how i fixed the cutting out on my bike and hope this helps someone! Its amazing the difference and it was a FREE fix!

[LukeM]

Cool!  Nice bit of diagnosis there.  Kinda makes sense why idling worked, but high speed was not.  The other thing to look at might have been the ignition advance system.

Also, where are you riding where 80 mph is legal?
Luke M

[1979Honda]

Thanks for the input. I'll keep that in mind. As far as the speed limit thing. I'm not one to race around on a bike. I just always wanted to see what this bike could do if it was running properly. And in case I ever decide to sell it. I would like it to be in good running condition.  

[LukeM]

No worries. I guess it's the dad in me, trying to bring a little reason to the discussion.  I see lots of ridrs, wearing shorts, no helmets, doing all sorts of dangerous stunts. In a way, we all are ambassadors for our sport. The saner and safer we are, hopefully the more the car drivers will respect us.

And it Is a good idea to keep machines in good working order. I'm doing everything I can to get my bike shipshape.