In the near future I would like to upgrade the motor in my 250R. Currently it's set up for TT racing, so it's all top end. I will probably never race TT, so I would like something that has a good all-around powerband, but still fast on the top end. It will probably be used mainly for dune riding and some trail riding - but nothing extreme since I don't want to tear the bike up.

What are your opinions on the 310 kits vs. the 330 kits? Are the 310s more reliable or provide better cooling since the cylinder wall is thicker? Should I go with a power-valve setup? Should it be a stroker or not? Are the 350 and 400 kits too big for fun, dependable riding?

Thanks in advance for your help...

 

If you're going to go to a 310 you might as well go to a 330.
I've heard lots of good things about power valves but don't personally know anyone that has one or tried one.
If you go with a LRD 330 you won't be disappointed at all and they do stand behind their work. Just tell them what you want to do with it and they can tell you how they can set it up for your application.
Already hooked aren't you? lol

 

trapperb1,

Heck yea, I'm HOOKED!

I've mentioned this before, but I've always heard how people liked the new 4 strokes on the market, but the old 2 strokes were just so ADDICTING. I always wondered why...now I know. Now I'm kicking my myself wondering, "What was I doing back in '88 when these things were brand new? Oh, yea...GIRLS!" Now, it's like screw the girls, give me a quad (no pun intended )

 

I have no actual experience with the 310 or 330 kit, but have read that the 310 kit is more desirable in the dunes because the 310 has the ability to rev higher.

 

Hey BirdofPrey,
I've seen you at the 250R forum. Great having another enthusiastic member!
If you want to talk to LRD330r about his motor, I gotta tell you it's a pretty bad actor! He brought it Glamis over New Years, and although he had problems with it, the 330 did just fine in the dunes and didn't let the Shee's give him any trouble.
Riding the dunes at Glamis is different than dunes elsewhere. They're big and soft and after a couple of days you start to understand how to ride them. Horsepower and torque are a real necessity there.
You can also check out MacDizzy. Builds a bad actor also.
I remember the 80's. Shoot! I was already married & divorced by the time the 86 R came out! Couldn't buy one 'cause I was broke!! Now I'm remarried to a lady that RIDES! We have 2 Rs!
So, get the motor done (or not) and bring it out here from Texas. There are some things out here that are bigger than what you guys have!! LOL!

 

Has anybody had any personal experience, or know someone that has, with the FTZ Racing TRX400R Monster Motor? A guy I trust said he would be concerned about the amount of modifications that go into it and it may be a timebomb waiting to go off. It has plenty of power (65 HP on gas and 80 HP on alcohol), but I don't want that to outway the dependablilty of a little less powerful motor.

 

IF you want big bores talk with MP Racing. They are now taking the Polaris Sport 400 cylinders and putting them on the TRX250R bottem ends. They are producing big power with them and you do not need to weld the cases up the way you do with the Pilot cylinder conversions.

 

I don't have a 250R, but I've seen quite a few. From what I've seen, I would say to go with a company like LRD or CT Racing. If I had a 250R(which I really hope to get soon) I would probably get a power package from LRD. Some other ones I don't think wouldn't be that bad are Trinity Racing or the new PSI Genesis engine kits. I've heard some good things about these as well. But whatever advice I give you, the last and final decision will be in your hands.

 

I would go with LRD, Cutris Sparks, Duncan, or MacDizzy.
I would stay away from CT, Trinity, and the less reliable 400 and over kits. macdizzy@macdizzy.com AKA Macdizzy can get a lot of HP out of a smaller 270cc bore.
ERIC

 

Thanks for all the replys. I was really impressed with LRD - and still am - but since I have come across PSI Performance. They offer a 425cc kit that makes 72hp and appears to be 'state-of-the-art' AND dependable. I understand they are know for their snowmobile engines and are now using their expertise in ATVs. They're not cheap (looks like a complete package will push $4k), but sounds like they have a good reputation.