RhythmNSteel
CB750 Member
Hey All! I'm new to the CB750 world and purchased a 81 DOHC CB750F with 31k miles about two weeks ago for $330 with a clean title. I previously finished up building a Ryca Motors bobber based off a 96 Suzuki Savage LS50. I'm now venturing out for my second build and decided on building a cafe racer out of what I have now.
Moving on straight to the point. I got the bike in non running condition. It has been sitting for some years and previous owner had it as a spare parts bike. By the looks of it thought, who ever worked on it last ghetto rigged a lot of things in it using mismatch bolts and what not. I ran a compression test with out the carbs on and bypassing all the electrical and jumped it from the starter hooked up to my external battery jumper. I tested the cylinders starting from 1 at about 150psi then gradually went low to 50psi on cylinder 4. I drained the oil then added a little mystery oil down the spark plug holes and let it sit for about a day. Now the second time checking compression I get about 120psi across all 4 cylinders which is still pretty low but all cylinders are in the same range.
The carbs seem to be ok to use, but they def need to be rebuilt and the slow pilot jets are pretty stuck in there and I don't want to fuss with it. Im looking into purchasing new CR carbs during the build process. What I'm wondering is if it's worth to try and get the bike running and see how it functions first before I pull it and see whats going on inside. Or just go right on in and crack it open. The wiring seems to be all there but may need to replace the starter solenoid and some fuses.
So, what I'm looking to find here is some suggestions and what to do next? Do I try and get this motor started or go right on inside and start rebuilding it? Here are some photos as to how it currently stands. Any advise would be greatly appreciated. Thanks a bunch in advance. I shall be lurking this forum in a quest to help me turn this bike into something awesome!
Moving on straight to the point. I got the bike in non running condition. It has been sitting for some years and previous owner had it as a spare parts bike. By the looks of it thought, who ever worked on it last ghetto rigged a lot of things in it using mismatch bolts and what not. I ran a compression test with out the carbs on and bypassing all the electrical and jumped it from the starter hooked up to my external battery jumper. I tested the cylinders starting from 1 at about 150psi then gradually went low to 50psi on cylinder 4. I drained the oil then added a little mystery oil down the spark plug holes and let it sit for about a day. Now the second time checking compression I get about 120psi across all 4 cylinders which is still pretty low but all cylinders are in the same range.
The carbs seem to be ok to use, but they def need to be rebuilt and the slow pilot jets are pretty stuck in there and I don't want to fuss with it. Im looking into purchasing new CR carbs during the build process. What I'm wondering is if it's worth to try and get the bike running and see how it functions first before I pull it and see whats going on inside. Or just go right on in and crack it open. The wiring seems to be all there but may need to replace the starter solenoid and some fuses.
So, what I'm looking to find here is some suggestions and what to do next? Do I try and get this motor started or go right on inside and start rebuilding it? Here are some photos as to how it currently stands. Any advise would be greatly appreciated. Thanks a bunch in advance. I shall be lurking this forum in a quest to help me turn this bike into something awesome!
