cr250 head mods for trail riding


6 replies to this topic
  • ulmanb

Posted October 02, 2007 - 02:38 PM

#1

I am thinking of getting my old 1996 cr250 back for a spare/buddy bike. The bike is basicly stock except for a wiseco piston and PC pipe and boysen reeds.

Problem is, I want it to react (engine wise) more like a KTM 2-stroke (smooth power from bottom to top). I am currently riding a 06 200xcw and I really like the smooth overall power.

I have ridden a 2001 with a flywheel weight, but the power is still pretty abrupt for single track. Has anyone had their head reshaped to make it have more low end and a smoother transition thru the upper end? if so, please share your feelings on the results.

Thanks

  • skipn8r

Posted October 02, 2007 - 06:05 PM

#2

I've experimented with the thinnest Cometic base gasket (0.010" thinner than stock) compared to the stock thickness gasket on our 285. The change in power wasn't drastic, but it definitely comes on at lower RPMs with the thinner gasket. If you combine that with a very large flywheel weight, a head milled for optimized squish clearance and the appropriate pipe, you could probably smooth things out quite a bit.

  • xylicon

Posted October 02, 2007 - 07:27 PM

#3

Don't those motors already have electric like power? My 1994 (same bike) has the smoothest powerband I've ever experienced, what more could you ask for?

Bike is stock btw.

  • ulmanb

Posted October 03, 2007 - 02:01 AM

#4

Honestly, I havent ridden the bike since I sold it to him 5 yrs ago, but I have fond memories of it. He has only ridden it once other than a few zips up the road each year.

I cant remember exactly what the power was like, rode someone elses 2001 with a flywheel weight and it was definitely a handful in the tight woods when comparing to a 300xcw and a 200xcw.

  • sndmn2

Posted October 03, 2007 - 05:06 PM

#5

I have ridden a 2001 with a flywheel weight, but the power is still pretty abrupt for single track. Has anyone had their head reshaped to make it have more low end and a smoother transition thru the upper end? if so, please share your feelings on the results.

Thanks


A little twitchy between the shrubs was it? I swapped out the s7 nozzle for the s8 last weekend. I took it to Lincoln Hills and Evart. Tamed it down a bit but what I"m thinking is either going back to stock jetting but probobly I"ll bypass that step and go with the Kehin "99" carb. For $150 in the TT Store it might be the easiest alternative.Then the Rekluse. Then the Sicass duel sport lighting kit. Then a trip to S.S.for a plate. Next years enduro bike. Picking up the 450exc after being in the saddle for 4 hours was just to much for my 49yr old bones.

See yas in a couple of weeks.

Another alternative may be to put a wide ratio tranny set in. I"m not sure where to get one but somebody told me you could do it.

  • ulmanb

Posted October 03, 2007 - 06:32 PM

#6

A little twitchy between the shrubs was it?


Yea, little more than I was ready for. Cant remember if my old 1996 was that abrupt as I never rode it in the really tight stuff.

I swapped out the s7 nozzle for the s8 last weekend. I took it to Lincoln Hills and Evart. Tamed it down a bit but what I"m thinking is either going back to stock jetting but probobly I"ll bypass that step and go with the Kehin "99" carb.



The 99 carb supposed to be the cure?

"

Picking up the 450exc after being in the saddle for 4 hours was just to much for my 49yr old bones.

What the hell was it lying on the ground for??:confused:

Another alternative may be to put a wide ratio tranny set in. I"m not sure where to get one but somebody told me you could do it

I actually looked into that option with my crf450 (takes virtually the same kit with a couple shaft swaps from a donor cr250 tranny). Anyway, the kit was no longer available from baja designs and used they are few and far between.

see you next week.

  • GlobalWarmer

Posted October 04, 2007 - 12:04 PM

#7

I had my 95 ported and 265'd by Gorr. (I guess he doesn't do it anymore). Lots smoother. Better climber now. I had lots of pinging problems until I switched to 100 octane when it's hotter than 75-80 degrees.


5 speed transmission

http://www.madmaneng...m/wideratio.htm





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