power now and rad valve on a rm 125? any other go fast mods?

[250racing]

has anybody tried a powernow or a rad valve on a 125 bike i am trying to set up my 04 rm 125 for woods racing and so far the only thing i have done to it is adding a 2 teeth larger rear sprocket.

the reasons i chose a 125 are :
im light weight 130 pounds and short 5´5"
i love 125 two strokes
i got it new at a great price basicly traded a 03 ktm 250 sx for the new zook.
last time my ktm 250 rfs needed a piston and valves it was like 700 usd.
i dont race for money just for fun in the a class in mexico.

i have already read a thread with some mods from marcus gumby but it seems like his bike was tuned for top end not rideability.

thanks all the input is welcome.

 

[robwbright]

As a cheap experiment you could try dropping a tooth in the front. It's about equal to adding 3.5 teeth in the rear.

I haven't tried the valves.

I don't think you'll find a better mod than a 144 overbore with porting, but it's a bit pricey. . .

 

[250racing]

As a cheap experiment you could try dropping a tooth in the front. It's about equal to adding 3.5 teeth in the rear.

I haven't tried the valves.

I don't think you'll find a better mod than a 144 overbore with porting, but it's a bit pricey. . .

thanks but i fear that the bike might be a bit slow for the faster sections if go to shorter gearing.

i heard that the 139 kit was the one that had the best bang for your buck and reliability but i dont know if that is an option living in mexico. i dont know if it would get through customs alive. i also have a concern with pistons who sells them? how much do they last? will they still be available in 3 or 4 years? how much do i expect to pay for a kit like that? is it bolt on?

i know thats way too much questions maybe you could give me a link and i will do the investigation myself thanks.

 

[dirtbikegeek]

I would go with the 144 kit,a Pro Circuit pipe,Boyeson reeds,re-jet,wiseco pistons and rings,and the rad valve.

 

[robwbright]

i also have a concern with pistons who sells them? how much do they last? will they still be available in 3 or 4 years? how much do i expect to pay for a kit like that? is it bolt on?

i know thats way too much questions maybe you could give me a link and i will do the investigation myself thanks.

The pistons I use are manufactured by Wiseco and designed by Eric Gorr (who built my motor). They're regularly available thru him and thru any local shop that will order an aftermarket piston for you. You could also order yourself through the internet. Eric's 144 piston design weighs 16 grams (about 1/2 ounce) more than a stock 125 piston, so there's not much extra weight there to put stress on the crank. One fellow here was 200+ lbs and was racing a 2002 RM144 at very hilly Glen Helen. He rebuilt the crank after 18 months of every weekend racing. I thought that was pretty good reliability.

I sent off the motor and received it back in a week and a half. It was $450-$500 for the overbore, plating, port, polish, head mods, case mods, piston, ring and re-assembly. The kit adds 6-8 HP - i.e you'll go from a stock 32 HP to approx. 38-39 HP. The effect is amazing. I went from 11/52 gearing to 12/50 gearing and I'm still a gear lower everywhere on the track. Further, the bike still revs out better than stock.

However, Eric is out of business until maybe September or October. Others do the work, but he was definitely the most reputable and also the least expensive.

His website (currently being remodeled) is http://www.ericgorr.com

You could also check RPM Motorsports and others.

 

[kawicam125]

go with the 144 kit if youre looking more power, a pro circuit platinum pipe, a pro circuit R-304 stainless shorty silencer, boyesen power reeds, rad valves, wiseco piston and rings, and re-jet.