Suzuki Forum - Suzuki Enthusiast Forums

I recently bought a 1996 Suzuki DR350 (off road version with the flat slide pumper carb). The bike misfires and (occasionally) backfires in mid to high revs (especially when riding, not so bad when rev'ing in neutral). It idles & operates in low revs just fine. I initially attributed this to bad/gummed gas in the carb since the previous owner told me the bike had been standing for 1 year and hadn't misfired previously.

I've given the carb a really good clean (it *was* badly gummed) and properly adjusted the pilot jet. This has helped the backfire problem a bit, but the misfire still occurs. It's like hitting a rev limiter in mid range. If I keep the throttle wide open, I eventually lurch up into high revs but it randomly misfires all the way up.

So then I thought it might be ignition rather than carb (the unburned gas in the exhaust causing backfire). I've replaced the plug, cap & coil but to no avail. I've also tested the kill switch (that's fine). There's nothing else that cuts ignition e.g. kickstand switch.

Something else I noticed is the front section of the exhaust glows orange with heat - Not sure if that's normal for the DR350 or a consequence of gas burning in it or something even worse like an exhaust valve timing problem.

So now I figure it's a problem with the CDI unit, magneto or valve timing.

But I don't want to dismantle/replace any of these blindly. Is there some way of root causing this issue e.g. is there a reliable way to test my CDI unit etc?

Thanks!