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XR250 top end Question
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Posted by: Rhodester---------------------
My son has a '97 XR250 that we're about to install a 277cc set up in. My Clymer service manual for it seems pretty generic and applies to too many different Honda 4-stroke models. It seems to be inferring that the engine has to be removed from the bike to do the top end. What about it, is that really true?
Posted by: morbidsmurf---------------------
I have a 2000 xr250r. when i did my top end i did not need to remove the engine. you have to remove the coil b/c it get in the way. also oone of the valve cover bolts is really long and cant just pull out b/c it hits the frame. you ahve to loosen it asnd then tip the valve cover and then pull out the bolt. Where are you located i would be willing to give you a hand if you were close. I live in Upstate New York.
Posted by: Rhodester---------------------
morbidsmurf, Thanks for answering my question. That will save me alot of extra wrenching. I live in the Boise, Idaho area. That's about 2500 miles from you! Thanks for the offer though. My state is much larger than NY and only has 1.1 million people. We have lots of mountains and wide open desert. Even with that and being one of the most conservative states in the union they're trying to lock up as much land as possible to ORVs. Big government has its drawbacks everywhere. Still (for now) we have tons of places to ride without seeing hardly anyone on the trails.
Posted by: morbidsmurf---------------------
what else are you doing to the XR. i have just a high compresson wisco, a hot cam's cam, a nice k&N and an after market exaust tip. the cam made a big diffrece. I primarly ride in orchards but do a couple harescrables and enduro's.
Posted by: Rhodester---------------------
I've pulled the baffle, ground off the insert and put just the round hole part back on (with an enlarged hole) to keep some of the sound down. I plan on grinding the weld inside the head pipe and breathing on the filter area a little. I'll also rejet. I already put stiffer spring in front and back. If I go with a more aggressive cam will it adversely affect the bottom end grunt? My son wants more power but wants to keep the bottom end power characteristics. Is a bigger carb needed to maximize the cam? How much of a difference did the cam make?
Posted by: morbidsmurf---------------------
the cam was noticable. it seemed to help power everywhere. I bumps the bottom up a little but it give it a big boost in mid to top power. i didnt change the carb but i didnt go with an overbore. i would try calling the people at xr'sonly and ask them. they seem to know there stuff.
Posted by: Patman---------------------
My 284 runs the stock carb just fine. Needed some fatter brass but that was all. Massive amounts of low to mid (as I wanted) and the Thunder Alley exhaust with Kirtzman spark arrestor it light years better than the stocker no matte how I modified it.
Posted by: Rhodester---------------------
Based on what I've told you about the mods I'm making, what do you think my starting point should be with the jetting (including needle clip)? I'm at about 3000' elevation in a dry climate. Thanks for the input!
Posted by: Patman---------------------
To be honest I'd have to pop the carb an look at what I finally ended up with. I'd take a stab that I'm running 48 slow & 145 main but I messed around with it so much I can't say that's for certain. I'd suggest grabbing a few different jets and then experiement based upon your fuel/elevation/temps/air density/riding style to see what ends up working best for YOU.
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