1 Starting issue, low comp in all cylinders after head job Thu Jun 22, 2023 5:48 pm
sparkplug69
active member
Hey guys,
Having some issues with my k100 from ‘85. This is my first fuel injected bike project and I am still learning.
Let me describe the situation:
I bought this bike with 68,000 miles on the engine. I bought it non-running and quickly realized she was do for a valve job and decking. I had that taken care of by professionals and have replaced many parts along with it. I have replaced the fuel pump and filter, the head gasket (evidently), miscellaneous tubing and cables and have had the injectors professionally cleaned.
I finished putting the bike back together today and cranked it over without the plugs in. I am getting really good spark, and what seemed to be solid compression. After doing more tests with cranking it with the plugs in, I did not get any sputtering or signs that she would start except for one very loud back fire that shot a flame 6 inches out of the factory exhaust.
I then tested for compression and realized that cylinder 1 read 60ish psi, cyl 2 50 psi, cyl 3 10 psi and cyl 4 virtually 0 psi.
Is it possible that I aligned my camshafts timing incorrectly or that my valve spacing is too tight? I followed the manual in setting those up and simply aligned the two cam gears up with their respective marks while the cyl 1 was at TDC. After reading a thread I think it is possible that I wasn’t perfectly at TDC (as truthfully I eyeballed it), but even then I would expect some sputtering. I also checked and the HEC cover was slightly off, I have now fixed it and centered it but that doesn’t not resolve the low compression issue.
NOTE: I did not feel any resistance after manually turning the engine over several times slowly before I ever tried to crank it. I do not think I bent a valve for that reason.
Any help would be greatly appreciated, looking for some guidance and thanks for your help
Having some issues with my k100 from ‘85. This is my first fuel injected bike project and I am still learning.
Let me describe the situation:
I bought this bike with 68,000 miles on the engine. I bought it non-running and quickly realized she was do for a valve job and decking. I had that taken care of by professionals and have replaced many parts along with it. I have replaced the fuel pump and filter, the head gasket (evidently), miscellaneous tubing and cables and have had the injectors professionally cleaned.
I finished putting the bike back together today and cranked it over without the plugs in. I am getting really good spark, and what seemed to be solid compression. After doing more tests with cranking it with the plugs in, I did not get any sputtering or signs that she would start except for one very loud back fire that shot a flame 6 inches out of the factory exhaust.
I then tested for compression and realized that cylinder 1 read 60ish psi, cyl 2 50 psi, cyl 3 10 psi and cyl 4 virtually 0 psi.
Is it possible that I aligned my camshafts timing incorrectly or that my valve spacing is too tight? I followed the manual in setting those up and simply aligned the two cam gears up with their respective marks while the cyl 1 was at TDC. After reading a thread I think it is possible that I wasn’t perfectly at TDC (as truthfully I eyeballed it), but even then I would expect some sputtering. I also checked and the HEC cover was slightly off, I have now fixed it and centered it but that doesn’t not resolve the low compression issue.
NOTE: I did not feel any resistance after manually turning the engine over several times slowly before I ever tried to crank it. I do not think I bent a valve for that reason.
Any help would be greatly appreciated, looking for some guidance and thanks for your help