Higher Top End

[fatguy250sx]

I was able to find a 300cc big bore kit for my 250sx but I was wondering what I could do to raise the top end. Would larger rear tires work? Anything else I could do? All that power seems like a waste if it tops out too quickly.

Thanks

[madmax]

Taller tires WILL incease top end...beyond that and the usual engine mods I have not found any other way to raise the top speed.
I'd like to see alternate ring and pinion ratios be produced by the aftermarket but I dont think that will ever happen.

[fatguy250sx]

Wow Max thanks for such a quick response. How tall do you suppose I go above the 22 stock size? 1st gear is pretty torqy so I am really not worried about losing bottom end power. Do you think 25's would make a bit of a difference?

[fatguy250sx]

Also I figured I would tell you what I am planning to do and that you might have some suggestions or warnings:

300cc big bore kit
140 main jet
Cut Airbox lid
K&N High Flow Air Filter
Cobra Steel Silencer and header pipe
Taller Rear Tires
Extend the swing arm 5-7 inches
Stonger shock for my weight

[madmax]

guy - I dont know much about the 300cc big bore kit, but I dont think a swingarm extension is likely as the driveshaft would have to be extended also... the 25" tires will definately help (I went from 22 to 20 and the slowdown was obvious). Just watch the clearance between the tires and rear fender (especially since the suspension is being compressed :) )

[fatguy250sx]

Yeah I was thinking about that as well. Looks like I have to fix my shock problem before I go with bigger tires, my 22's just barely clear as it is now. Thanks for the info.:doh:

[250sx]

you can get a custom shock for anything if you have the $$$. 25"s will be a TIGHT fit on an SX. if you find a source for the 300cc kits let me know. :D

[MR ATC]

not too knock the 250sx but i think with what your after a bigger sport trike would be a cheaper and better performing way to go.

try a 350X

[Mr. Kasey]

on a 250sx extending the shaft drive swingarm is impossible!!!
UNLESS you own a machine shop and have time to build a longer driveshaft,,,, :D it can be done i guess if you got the $$$$$

[da_catt]

a drive line shop for trucks might be able to extend the drive shaft.

[fatguy250sx]

I was thinking the same thing. I was looking into a Tom Woods drive shaft for my Jeep Wrangler when I had the thought. He builds custom drive shafts for lifted wranglers, and I am thinking that this might be right up his alley. Whether or not he would do it is the question. I am going to email him and I'll let the board know what he says just in case someone else wanted to do it. I did see one 250sx that had an extended swingarm, but I am not sure how he did it and I am still waiting on an answer.

Thanks

[fatguy250sx]

Yes I would love a 350x however I haven't been able to find one near me, so that's why I was going to work up the 250sx.