Hey fellow riders, I'm in need of some assistance. I have a 1978 Honda CB750F super sport and the carbs have been given me some trouble.
A little back ground I bought this bike from a gentleman on CL, bike has 13K and is in pretty good shape, pod filters with a 4-1 exhaust. He said that it needed a little bit of carb work to make it awesome, and the main jets have already been jetted up but it does start up and run good but when you drive it around under load it pops and lags above 4K rpms. I take the bike to a local bike mechanic here and had them clean, and sync the carbs and give the bike a look over to see if there is any underlaying major problems. I got the bike back drove it around and it was great no popping or lag all the way home. the day after next the problem comes back. It will start and run great but pops and major performance lag at full throttle above 4K rpms. Call the mechanic back and he was like probably need to jet the carbs. at this point I'm like blah I'll just do it my self I have cleaned and tuned carbs before I was just working on another project plus school and work and I just wanted to ride.
I order the jet kit, the main jets on the carbs were all set to 125 and the secondaries are 42, I'm right at sea level so I set carb 1 and 4 main jets to 127 and carb 2 and 3 I left at 125. put everything back together take it for a ride it felt better but still a little bit of lags and some pops here and there. So Friday I start adjusting the needles and couple hours later take the bike for a spin again for the rest of the day this time and absolutely no issues. take the bike out again Saturday night bam issues are back. So this afternoon I again spent a couple hours tweaking the needles but couldn't get it just right this time.
The bike idles pretty good but every once in a while the idles will fluctuate for a minute of two then it goes back to normal. the spark plugs look pretty close they are a medium charcoal grey color, pipes seem to be evenly hot, I'm sort of at a loss now.
Sorry for the novel any help would be greatly appreciated
I can post some pictures later
A little back ground I bought this bike from a gentleman on CL, bike has 13K and is in pretty good shape, pod filters with a 4-1 exhaust. He said that it needed a little bit of carb work to make it awesome, and the main jets have already been jetted up but it does start up and run good but when you drive it around under load it pops and lags above 4K rpms. I take the bike to a local bike mechanic here and had them clean, and sync the carbs and give the bike a look over to see if there is any underlaying major problems. I got the bike back drove it around and it was great no popping or lag all the way home. the day after next the problem comes back. It will start and run great but pops and major performance lag at full throttle above 4K rpms. Call the mechanic back and he was like probably need to jet the carbs. at this point I'm like blah I'll just do it my self I have cleaned and tuned carbs before I was just working on another project plus school and work and I just wanted to ride.
I order the jet kit, the main jets on the carbs were all set to 125 and the secondaries are 42, I'm right at sea level so I set carb 1 and 4 main jets to 127 and carb 2 and 3 I left at 125. put everything back together take it for a ride it felt better but still a little bit of lags and some pops here and there. So Friday I start adjusting the needles and couple hours later take the bike for a spin again for the rest of the day this time and absolutely no issues. take the bike out again Saturday night bam issues are back. So this afternoon I again spent a couple hours tweaking the needles but couldn't get it just right this time.
The bike idles pretty good but every once in a while the idles will fluctuate for a minute of two then it goes back to normal. the spark plugs look pretty close they are a medium charcoal grey color, pipes seem to be evenly hot, I'm sort of at a loss now.
Sorry for the novel any help would be greatly appreciated
I can post some pictures later