250cc 2-Stroke low end?

TxCr250

Member

Aug 24, 2006

66

0

• Aug 25, 2006

• #1

I have a stock 06 Cr250r and wanted to give it a little more low end for trail riding and some small track riding, I rarely get it to full throtle "wide open", other than in an open field but my question is...What front/rear sprocket size would yield better results? I'm not certain of the stock size but I think it 13/49. So I'm thinking 13/51t or52t. Any one have any thoughts/experience with this and how mucn of an improvement does this yield in the low/mid end of a 205cc 2-stoke? Also include what brand is good, ie Renthal, Tag etc, thanks for your time and opinions.

 

M

mark808

Member

Aug 22, 2006

55

0

• Aug 25, 2006

• #2

i cant believe you need more bottom end. i have a 96 kx 250 when i first got it i could hardley keep the front wheel down so i went one down on the rear sprocket. now its a lot more controlable and trust me it has no problem getting the front up.i like renthal but only because its what ive used since i was a kid. if you can get the tag cheaper id go with that

 

J

j32

Uhhh...

Jun 8, 2006

202

0

• Aug 25, 2006

• #3

well renthal doesnt list a smaller front tooth sprocket so try a different one
-moose makes a 12 tooth one its too bad there isnt a 11

 

W

WLKDX

Member

Dec 7, 2004

43

0

• Aug 26, 2006

• #4

If you are talking pull from idle, less stalling and smoother, the first thing to do is a flywheel weight. On my Husky (which had the same 38MM TMX carb as yours) I swapped to a 36MM Keihin PWK. Starts easier, runs beautiful, nice smooth power, takes some of the mid hit out.

 

M

mtk

Member

Jun 9, 2004

1,409

0

• Aug 26, 2006

• #5

j32 said:

well renthal doesnt list a smaller front tooth sprocket so try a different one
-moose makes a 12 tooth one its too bad there isnt a 11

Click to expand...

Smaller front sprockets are a bad idea. The 13 is definitely as small as you should go on the front.

However, changing gearing won't increase low-end power, it will only make the engine turn a bit more revs for a given ground speed.

I had Eric Gorr do a Mo Betta port job on my 2002 CR250 and it filled in the bottom end power hole quite nicely. Alas, I don't know if Mr. Gorr will be reopening his business so I don't know where to point you right now.

A flywheel weight will also help with stalling and in tight situations, but the porting was the biggest positive change.

 

E

endofsilence808

Member

Dec 11, 2004

58

0

• Aug 26, 2006

• #6

i agree with mtk completly. gearing wont affect the way the power gets down. try a flywheel weight to smooth out power

 

darringer

LIFETIME SPONSOR

Dec 2, 2001

1,029

0

• Aug 26, 2006

• #7

Another problem with gearing it down is that it effectively shortens each gear. The time the engine is in the meat of the powerband for a given gear is reduced, therefore you don't use the torque of the engine as effectively. As MTK said, The Mo Betta porting does wonders for the powerband. I took it a step further and went with the 265 big bore with the porting on my '02. I had significant gains from the very bottom though the upper midrange. with the top end about the same as stock. I also ran a 12oz. flywheel weight. All of these things combined made for a good, all-around bike that worked well on everything from hillclimbing and tight single track to fire roads and mx tracks.