I just bought a 1988 TRX 250R and ride in the sand dunes here in Oregon. I was looking for opinions on which engine kit would be the best for the sand(hillshooting, trails, and drag racing). What bore size would be the best: 250, 270, 310, 330, 350, 425, etc...?? Powervalve or no powervalve?? I am not to concerned with porting, pipe, or reeds right now because that will most likely be included with the kit. anyway, I first thought bigger would be better but with a heavier piston comes less RPM's right? I am coming off of a modified 440EX so I want lots and lots of torque but still want it to rev way out. Is there really that much HP and torque difference between say a 270 and 330?? Sorry for the long post, I've just always had big bore 4-strokes and thought I would try a 2-stroke for a change. Thanks for any input!!

 

It's hard to beat a good 310 kit combined with the right pipe and carb set-up. The best part, is that 310 kits are totally bolt on, no machining of the bottom-end is required. If your bottom-end is in good condition, just bolt it on and let 'er rip! Powervalve cylinders are really expensive, and I'm not too sure you'll recieve much benefit for your type of riding. That money could be better spent elsewhere. If you want more, you can go up to 350 before you have to stroke the crank. IMHO, a 310 is a realy good way to go, if you do your homework now, you'll forego a lot of headaches and wasted $$$ down the road. With careful selection, most of the components on the 310 (head body, pipe, carb, intake, etc.) will work later on if you decide to "go big". Also, pick 1 engine builder and stay with them, don't "piece" an engine together. Two strokes are very dynamic, each component has a large effect upon the others. If one component upsets the "harmony" of the engine, you'll go backwards (in performance and $$$). Choose an engine builder with a good reputation, good customer service, and one that can deliver. Often times engine builders can't supply the product in a timely manner, keeping you from the trail.

One more thing, DO be concerned with porting, pipe and reeds right now. They have a HUGE effect on the performance and longevity of a 2-stroke engine, much more so than with a 4-stroke. Take all those things in consideration when you go shopping for an engine builder.

lump-dog

 

thanks for the info lumpdog, I definitely want to stay with the same engine builder and I know if I buy a kit from one place the pipe, reeds, and porting should all work well together with the rest of the kit. I was actually thinking about CT Racing's Powervalve 350 Kit mainly for the huge torque I think it could produce.

 

That's a lot of money for something who's success is questionable. If you're coming off a 4-stroke, and haven't ridden a big bore 2-stroke, you might have a "warped" sense of torque, especially in the sand. If you're going to be riding a lot in the dunes, you don't need an incredible amount of torque, anyway. Top-end is where its at in the dunes! A "conventional" 350 has tons of torque, and is practically unridable in the sand with paddles and a stock swingarm. Do your homework on the powervalve set-up. They're not what they're cracked up to be, and they have some tweeking to do before I'd spend my hard earned $$$ on one, IMHO. Find someone with a 310 or 350 and ride it, I think you'll be shocked at the power they produce.

lump-dog

 

Give dave moore at MP Racing a call. Hes shop is in oregon somewhere and he does excellent work. Hes at the dunes doing testing every weekend. Stay away from CT Racing. They are going down hill.

I think mpracing.com is daves web site.
good luck

matt

 

i would highly recommend psi. they make awsome power but are on the costy side. go to psiperformance.com

 

mxer, we were looking into a ct 350 kit as well. not a good idea? do have any other info on this guy in oregon?

norm, where at in oregon do you ride?

 

Ash,
PSI has not proven to be reliable. I see more negatives than positives with PSI.
ERIC

 

I've heard of problems with the CT kit as well...plus the portjob on the cylinders is very questionable.

Dave at MP Racing's site is Motomallusa and I HIGHLY recommend him, he is a bit busy right now, but you will not regret sending your motor to Dave. Feel free to call him and discuss your engine build, unlike many motor builders he'll tell you exactly what he is going to do and why, not the 'send me your motor and Ill make it fast' crap.

also, FYI, MP is located in Salem, Or

If you want to see pictures of my 250R with the MP engine and the porting and engine build pictures, go to my page at http://www.valleycity.net/pete

Click on My TRX250R and you should see everything from there...also, under 'Ride Trips' the newest trip to Silver Lake was on my MP motor...it faired VERY well against any modded 250R and most Banshee's, usually beating the majority of them.

 

How 'bout ESR? Bolt on 310 kits are in stock and ship within 1 week of placing the order. The turnaround time on 330, 350 and 370 kits is 1-2 weeks.

lump-dog