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Cr500 swap?


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I ran a piped 98 CR500 for a couple of years. I think the main reason they discontinued the bike is that they weren't much faster than the PV'd 250s. I run a YZ 250 now and it would pretty much have run with my CR500 (and is WAY faster than my old YZ 490). The 500 with porting would be a whole 'nother story- If it was set with a good woods type port, it would retain some bottom and actually flow on top. Something to keep in mind anytime a CR500 swap is considered is the massive vibration of these motors. I can't remember the fix, but I heard a lot about in in the days when the 250R was king and everyone was doing this swap.

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i have never in this area seen a 250 Pved or not hang with a 500 in a drag or hillclimb. it just doesnt happen. are you talking about in sand? the cr500 cylinders dont need any more bottom end or midrange for that matter. they need a topend. my cr500 motor is a 4mm stroker with a top end port job and it lost nothing on bottom. before i had it stroked it had a gorr top end port job and if anything only gained on bottom, so you def dont have to worry about the bottom end on these motors. not that im doubting you heard about the 500's vibrating but id be glad to let you ride mine. it does not vibrate bad and you dont even notice it when you are riding. the only fix i would know of is a counterbalancer which the 500's dont have.

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ported and piped 250's with or with out power vavles can't even get close. by the time i hit fourth they are about 300 yard back and fading fast. my bad on those hp estimates it more like 65 rwhp with around the same or slightly higher torque number and its not just ported. this is all just rough estemates. it does feel like alot more than it actually is ,but who really needs to be going over 100 mph on two wheels in the dirt any way right. trie to attach a dyno shee but it too big

Edited by fast500#12
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I'm talking about the sand, I never ride in the dirt. I'm sure that dirt is a different situation in regard to racing. In the sand (hillclimbs), my piped 98 500 would easily beat stock banshees, but merely stay even with the piped ones unless there was room to get into the upper gears, where they would run out of power and my toque kept pulling hard. Technique was to give 1/2 throttle in 1st gear, a little more in 2nd, then fan thru the rest of them. This would carry the front end for the first 100 yards or so. The main problem in the sand is traction, and the pipier bikes lay down power a lot better than the torquey ones. The hard snap of horsepower 'locks up' the sand, where the slower delivery of four strokes and the big bores let the sand flow a bit, causing mushy traction. Quads have more than twice the tire surface area, and aren't trying to dig to china for the first hundred feet. So maybe this is what I meant when I said that the small bores run with the 500s. In the sand, power delivery affects traction in a big way.

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