After I got my 1975 Honda MR175 running, it ran great and had a lot more power than it used to. (new used piston and cylinder) Well, after about an hour's worth of riding, I stopped, put it in neutral, and let it idle for 30 seconds or so while I adjusted the preload on the shocks. As soon as I started riding again, I realized something was wrong. It now has less power than it did and sounds different. I parked it and pulled the pipe off to look in at the piston. It looks fine, compression is the same, so I figure it didn't sieze. Next I took off the sidecover to check the flywheel (for those of you who haven't heard, I had to lock-tite a chunk of the crankshaft back into place, right next to the woodruff key.) and it looked ok, though I did not pull it off to really check it carefully
I figure what must have happened is that the flywheel shifted slightly on the crankshaft, changing the timing. (I think that would retard it slightly, but I'm not totally sure) The bike idles fine, though with slightly more piston noise. (very slight) When accellerating, the bike sounds and acts normal at low rpms. when the revs start getting up there (it doesn't have a tach,but I'd guess 3000 rpms and higher) it starts sounding really crappy. Instead of revving smoothly to a nice "scream" sound, it has a dead spot as far as power goes, and I can hear a loud(er) sound from the back of the muffler every time the piston fires. basically it just sounds rough. It sounds a lot better (almost normal) when under a heavy load, like accellerating in 3rd and 4th.
Is this a timing problem, or should I look elsewhere?
I figure what must have happened is that the flywheel shifted slightly on the crankshaft, changing the timing. (I think that would retard it slightly, but I'm not totally sure) The bike idles fine, though with slightly more piston noise. (very slight) When accellerating, the bike sounds and acts normal at low rpms. when the revs start getting up there (it doesn't have a tach,but I'd guess 3000 rpms and higher) it starts sounding really crappy. Instead of revving smoothly to a nice "scream" sound, it has a dead spot as far as power goes, and I can hear a loud(er) sound from the back of the muffler every time the piston fires. basically it just sounds rough. It sounds a lot better (almost normal) when under a heavy load, like accellerating in 3rd and 4th.
Is this a timing problem, or should I look elsewhere?