[buzzard]

I have some recent experiences that I hope help someone else. I had one of the devil bikes (2002 250xc) that I just couldn't jet. It started and ran fine right up to mid-range, then refused to take throttle, and wouldn't rev out. It turned out to be ignition problems. I put a timing light on it, and it had the wierdest advance curve you could imagine. Right above idle, it jumped to full advance, then about midrange, it went back to no advance. I always thought that a CDI either worked, or it didn't. I was wrong!


I used an inductive timing light. It uses a pickup that clamps over the plug wire, and any old 12v battery. I put the piston at TDC, and marked a line on the rotor, and a corresponding line on the engine case. Using a dial indicator, I also marked a line on the engine case representing 1mm BTDC.


I was fortunate to find an ignition on this site, in the For Sale forum. When it got here, I installled it and checked it's advance curve. I wouldn't call it a curve, exactly. Just above idle, it went from no advance to full advance. It stays at full advance until the engine returns to idle. Actually, my 250 runs great with this ignition. I wondered if this was normal. I have a friend with a 2006 300EC. I went over to his house, timing light in hand, and we checked his bike's "curve". My friend has never been able to get his bikes top end jetted correctly. It has never had that top end rip. Well, his ignition started at full advance, right at idle, and smoothly went back to no advance as the RPM increased. BAD IGNITION!


My friend ordered a new ignition. They go $300+. When it got here, we installed it. It is different than mine, in that mine uses 7 wires to connect to the wiring harness, his uses a multi pin plug. Looks like the same unit otherwise. We timed it. It has the same curve (or lack there-of) as the used unit I purchased. Right above idle, it jumps directly to full advance, and stays there. His 300 now runs great. The top end rip is there. He never even thought he might have a bad ignition. He's been jetting it for about a year.


Here is an odd side note. I searched kokusan on eBay. Up came shifter kart ignitions, by Kokusan. I bought one for $50. It has exactly the same wiring harness as my Gasgas ignition, same colors and connectors. I installed that one, and guess what? The same advance "curve", and it runs great. It is a black box (hence the name, I guess), about 3"x4"x3/4". I mounted it to the rear fender.


So I guess the take home message here is to put a timing light on your bike. It's quick and easy to do, and you may just find out a lot. Also, it pays to set your initial timing. I had to slightly modify my stator plate to allow it to rotate enough to set the timing at 1mm BTDC.


If anyone has knowledge of different advance curves, or ignitions, I would like to hear about it. I'm going to check another friend's 2005 KTM 250EXC soon, and see what Kokusan sells to KTM. I am a little disappointed in the lack of technology in the ignition on these 2stroke GasGas bikes. I have to wonder how they might run with an ignition that actually has a curve, in that it advances continuosly as the RPM increases. Thanks, Buzzard