Ignition Timing!

[Bikerdman]

:) My son bought a used 2000 KDX 220, we both took it for a spin and he bought it the next week. The engine produced a very,very narrow powerband, so narrow that it seemed to be more like a motorcrosser than an enduro bike. After reading many posts ,especially about the carb,I found the power curve still not what I would expect of a woods bike
The previous owner installed K-30 pipe.I checked the carb 42slow, 145main and I put needle in 2nd. position,float pos. OK. Pulled top end,cleaned all valves,new rings. Underside of piston looked very dark. Reassembled,break-in, no.8 plug. Bike now runs better but not smooth transition through rev. range. Next I take Off air box cover,just louder intake drone. gas mix is 35:1.....:think lets try retarding the ignition timing!!!!!!!!!!! Yes THIS BIKE RIPS!!!!!:p

 

[spanky250]

Glad to hear you got it running to your satisfaction. Most people are afraid to mess with the ignition timing, but sometimes there are real benefits to doing so. My bike runs much better with the timing retarded slightly from stock, with better response down low and a smoother transistion onto the pipe, and in my experience, most Japanese bikes benefit from this. There is no cut-and dry answer to this, however, and the only way to know if you can gain anything is to experiment.

 

[Bikerdman]

Hey Spanky, I guess the machining tollerances very enough during mass production that can affect performance. Also slight differance in fuel octane and additives . I'm riding bicycles now, I gave up motorcycles in 92' after 25yrs. It really became frustrating in my lifelong homeland,Urban sprawl is causing many to race just to exist!
While helping my son tune the bike and as I thought back to" my days" I remembered something about the color of the underside of the piston,kind of like a plug reading. My 78 IT175's underside piston color would be a med. brown, the kdx was a dark brown so thats why we tried backing off the timing just a bit. Index marks are close,but not spot on. Now that he's running I can go back to putting miles on the old legs! :cool:

 

[MCMAN56]

How Much?

How much did you retard the timing? Did it improve the bottom end power or just smooth the hit?

Thanks

 

[Bikerdman]

ignition timing

I turned the plate counter clockwise. the reference marks are at the left mounting screw. The stock position was dead center, I moved 2/3 towards the retard mark. I* I I I don't have a degree & dial gauge just trial and seat of pants. Smooth,predictable power delivery. Didn't lose any power at all, just a little heat off the piston! Look at the under side of piston, if the color is dark brown or black that is a good sign of too much heat, back off timing a bit, your engine will be happy:)