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Going from PWK 39 tp 40.5

Posted: January 3rd, 2012, 7:45 pm
by knobby668
I picked up a atc250r that has a 310 cylinder and a 40.5PWK.
I am thinking of swapping the 39PWK off my 500.

Do you think if I just swap the jets everything will be good or do I need to change for the different size? Forgot how tippy these are lol.
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Posted: January 3rd, 2012, 8:06 pm
by Doppler
Nice pumper man! I had a fooler for a while, it was a blast. Have a 350x now...it's a blast too!

Posted: January 4th, 2012, 12:21 am
by NightBiker07
that is a badass 250R! :cool:

really wouldnt think swapping the carbs on the 2 bikes would make enough of an improvement for all the dicking with the jetting on both bikes, unless youre chasing high-rpm power on the 500.

Posted: January 4th, 2012, 5:02 am
by Roostius_Maximus
the 39pwk usually needs one pilot size smaller than the 41, otherwise the jetting can be very close just copying what you run

Posted: January 4th, 2012, 6:35 am
by knobby668
That is what I was looking for, thanks.

Posted: January 4th, 2012, 7:11 am
by Rhino89523
Sick 3 wheeler!

Posted: January 4th, 2012, 9:35 pm
by louis mielke
Swing arm is awesome!

Too bad it's not a 500. lol No j/k, I don't want to get into that argument here too. 310/330 vs 500. People like to fight about it all the time.

Posted: January 5th, 2012, 7:36 am
by knobby668
Ya, that was my idea when I bought this. It runs pretty strong the way it is so for now I am going to leave it alone.

Posted: January 5th, 2012, 8:06 am
by iggys-amsoil
Ever thought of swapping the forks side to side so that the axel is in the front? You'll have extra brake line but no problem. If I remember right your 350X is like that already.

Did that on mine way back then and it mad a big difference in arm and shoulder pump. Plus they look cooler that way. :wink: :lol:

Posted: January 6th, 2012, 3:24 am
by louis mielke
Changing from trailing to leading axle will change the handling on the 250r pretty dramatically. The 350x was designed with leading axle. Changing the rake and trail, could possibly make steering really heavy.

I've fought that battle on my conversion. Obviously mines a dirt bike frame and custom front end but through trial and error I've learned that the front end geometry can make the difference between a trike turning on a dime, or being unride-able.

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