A couple of days ago I changed the timing chain on my ’96 TRX300 2×4, ran into an issue with the change clutch not engaging the crankshaft when I put it back together, but with some help from shadetree, I managed to get everything put back together, and working properly. I also adjusted the valves (.006 at TDC of the compression stroke), changed the oil and filter, and gapped the spark plug that was set at .020 instead of .031-.035 (note: it ran ok at the smaller gap, but I wanted it set correctly). After I got it put back together, I took several short test drives of approximately 100 yards each to make sure everything seemed ok, and there no indications of a problem. In fact, it ran MUCH quieter than it did prior to the timing chain swap, and it accelerated smoothly.
Today I decided to align the front end, but when I finished that, I jumped on, started it up, punched the throttle a couple of time, and I thought I heard a faint knocking noise coming from the right side of the engine at the moment I hit the throttle each time, but not after the RPMs had increased. I was able to duplicate it with each subsequent blip of the throttle from idle. When I put it in gear, that’s when the knocking noise was much more discernible (i.e. louder and more pronounced). I did my best to pinpoint its exact location using just my ears and a long tube, but I could never get a specific location except that it really sounds like it’s coming from the top of the clutch cover, only barely….barely ahead of the oil filter — not directly below the cylinder (at least that’s my impression).
Since I had changed the oil, I figured I’d check to make sure I didn’t put the oil filter in backwards, even though I was certain I had not. I was correct, I had installed it correctly, and it was populated with oil, so I assume too that the oil pump is working.
At this point I haven’t opened it back up before I get some ideas from others. So, any suggestions?
Thanks!
Edit: It’s worth mentioning again that the knocking/slapping noise is ONLY evident when I first hit the throttle. Everything seems ok after the RPMs are increased.
Edit2: So as not to omit any possible clue, I should mention that I test rode it once today prior to aligning it, and it ran well. After aligning it, it was in 3rd gear, so I attempted to down shift it to neutral, but it would not. I tried rocking it like I had to do in the past, but that didn’t work either. For whatever reason it suddenly started shifting correctly without rocking it, and it’s shifted fine since (better than before I removed the clutches to change the timing chain).
