Hi guys,
I recently purchased a 1980 Cb750f which ran beautifully when i test ride it but on the ride home I noticed a huge drop in power and the bike would no longer rev above 5k and would miss fire and backfire when applying throttle near that rpm. Also below 4k rpm the engine would run rough and would stall if I let the rpm degrade further. I had to ride the clutch to keep it at 4k rpm and the bike had so little power that it could barely pull it's weight up my drive way riding the clutch!
I pulled the plugs and they were badly fowled but in otherwise good condition. I replaced them to make sure but the problem remains.
The bike also starts cold with no choke when cold and seems to run very rich from fuel consumption and smell (as well as the plugs).
I read on a forum that carb balancing could be the issue and took it to a mechanic today but he didn't think that would cause such severe symptoms. He also didn't even want to look at the bike because of its age and bitched the whole time a about not wanting to get "stuck with the job" if more things kept cropping up. I would have walked out of the shop then and there but I don't have the equipment to balance carbs, although I am regretting not buying them now!
I also put fresh fuel in the bike (98 octane) and checked the tank for contaminants.
Does anyone have any idea what could be causing this? My next step is to get the carbs cleaned in a ultra sonic bath.
Sorry for the wall of text, if there is any cb750 experts in Melbourne, Australia I would much rather give you the money than this mechanic!
Cheers,
Spangers
I recently purchased a 1980 Cb750f which ran beautifully when i test ride it but on the ride home I noticed a huge drop in power and the bike would no longer rev above 5k and would miss fire and backfire when applying throttle near that rpm. Also below 4k rpm the engine would run rough and would stall if I let the rpm degrade further. I had to ride the clutch to keep it at 4k rpm and the bike had so little power that it could barely pull it's weight up my drive way riding the clutch!
I pulled the plugs and they were badly fowled but in otherwise good condition. I replaced them to make sure but the problem remains.
The bike also starts cold with no choke when cold and seems to run very rich from fuel consumption and smell (as well as the plugs).
I read on a forum that carb balancing could be the issue and took it to a mechanic today but he didn't think that would cause such severe symptoms. He also didn't even want to look at the bike because of its age and bitched the whole time a about not wanting to get "stuck with the job" if more things kept cropping up. I would have walked out of the shop then and there but I don't have the equipment to balance carbs, although I am regretting not buying them now!
I also put fresh fuel in the bike (98 octane) and checked the tank for contaminants.
Does anyone have any idea what could be causing this? My next step is to get the carbs cleaned in a ultra sonic bath.
Sorry for the wall of text, if there is any cb750 experts in Melbourne, Australia I would much rather give you the money than this mechanic!
Cheers,
Spangers