my 1978 dt250.

[esworp]

after a carb rebuild 2x, I've gotten my new family member running.

I'm new to 2-strokes, and I can't tell if what I'm hearing is normal operation or something Bad. When its idling or cruising at a steady speed, the engine sounds like it's hammering something fierce along with the rpms. At first I was thinking "wtf, is the head loose or something?"

Things look ok, though. I haven't really put any serious distance on it, since it's still a major basketcase in other departments.

What are the odds that the timing is off and I'm hearing the 2-stroke analog to pinking? That said, someone mind pointing me at a how-to for setting the timing on my bike? I worked the Google on the Internet Machine, but didn't come up with anything... :[

 

[2strokerfun]

If it is pinging from detonation, it makes a unique sound and you really have to listen for it (assume you're wearing a helmet). My experience is that detonation is usually worse when engine is under a load, such as acceleration or climbing a hill. If you have a hammering, while going at steady speed, I'd worry about rod or crank bearings. I'd do three things: 1) pull head off and inspect top of piston; 2) pull cylinder off and inspect movement on rod bearing and inspect upper wrist pin and bearing; 3) pull left sidecover off and inspect stator for any movement. Someone may have a lot better answer than me, though.