WR250F Exhaust Cam Timeing Advance
- Thread starter tapyz250
- Start date
The WR exhaust cam is ADAVANCED by default and needs to be RETARDED to match YZF cam specs. To retard the cam timing it needs to be turned 1 tooth in the opposite direction of normal engine rotation.
Hey Rich do you have any suggestions on doing this? Is there any advantages to it? What will the power differences be? And in your opinion is it worth doing it? I have a buddy with this bike and he likes to ride the track more than he does the woods now! So I am trying to convince him:)
JohnT, I did this to mine - an NZ/Aust spec bike which I assume is closer to the Canadian spec than the US spec machines. Does yours have a single piece stainless muffler with non-removable end cap?
Whereas with the WR timing the bike needed to be revved to the moon to get maximum power and lacked in the lower to mid range, with the YZ timing the good usable power comes in much earlier and the lower to mid rev power is much greater. It becomes more of a mid range "grunter" with the YZ timing, allowing a higher gear to be used than with the WR timing in many offroad terrain conditions.
Absolute top end is about the same but "average power" through the WR gear ratios is much better.
Having experienced both timing setups on my bike, there is no doubt that this engine was always designed to use YZ timing and that WR timing was a compromise for the greater backpressure the stock WR exhaust would exert.
I had to go up two jet sizes when using YZ timing and a free flow exhaust is strongly recommended. I would recommend the YZ timing procedure unreservedly!
Whereas with the WR timing the bike needed to be revved to the moon to get maximum power and lacked in the lower to mid range, with the YZ timing the good usable power comes in much earlier and the lower to mid rev power is much greater. It becomes more of a mid range "grunter" with the YZ timing, allowing a higher gear to be used than with the WR timing in many offroad terrain conditions.
Absolute top end is about the same but "average power" through the WR gear ratios is much better.
Having experienced both timing setups on my bike, there is no doubt that this engine was always designed to use YZ timing and that WR timing was a compromise for the greater backpressure the stock WR exhaust would exert.
I had to go up two jet sizes when using YZ timing and a free flow exhaust is strongly recommended. I would recommend the YZ timing procedure unreservedly!
I have a 2001 wr250f, but the bike was manufactured in Canada. Would my bike not need this mod? Also I live in California where modifications are illegal on virtually everything. If I took it to an ohv area could they say anything?
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