Has anyone tried the 628cc big bore kit from four stroke tech?

 

Here is the link for those who haven't heard of it.

Four Stroke Tech

 

One of the magazines did a review of a GNCC racer from WV who had the kit installed. They said it was the fastest Polaris they had ever tested. I think he got 4th overall last year with his Scrambler.

 

ScramblerX,

Frankly, that kit is the ONLY way to get horsepower out of that (500 Scrambler) machine. It's just a shame that FST is so smart when it comes to motors, but so dumb when it comes to clutching. Basically, they use stock clutching. The magazine said that they were having problems with wheel spin. No duh, this is what happens when you add a ton of power to the machine and don't clutch for it.

The only reason that they said it was the fastest they've ever ridden, is because they haven't ridden a lot of modified Polaris machines. There isn't a great demand for them in So Cal. If you put them on modquads's machine or even mine, they'd see what real performance is.

 

Aw shucks Mike, thanks for the complement... I too had to laugh at that article. "We didn't modify the clutch, because we didn't feel it needed it" hahahahaha. Would be intersting to see that setup properly clutched. Bet there's some stump pulling torque.

Ken

 

Dontknowcrap,

Wow, now that is a fitting name if I ever heard one. It's constantly amazing to me how some children can get on their parent's computer. Haven't these parents ever heard of passwords?

In order to answer your question, I will have to lower myself to your level. First off, ALL quads are based on old designs, yes even the Cannondale you mentioned. Aluminum frames have been around for years, as have fuel injection. Please don't mention TRX250Rs. If you haven't noticed lately, they haven't produced them since 1989 (that's 13 years if you can't count). Dollar for dollar and cubic centimeter per cubic centimeter, modified 400CC Polaris machines will easily hold their own (motor wise) against DS650s, Raptors, 250Rs, 400EXs, Banshees and Cannondales. The simple fact that they are cheaper to buy, and cheaper to modify bears this out. While it is true that you can buy a stock DS, Raptor, 400ex, Banshee and Cannondale for the price of a modified Scrambler, you won't get anywhere near that level of performance.

As far as bashing on any successful racers or engine builders. I was trying to give FST a compliment. Their 628cc kit is the ONLY way to milk more useable power out of the 500cc Polaris four strokes. It's the clutching that FST doesn't understand. You simply can't expect to put more horsepower and torque out of a motor and keep the clutching the same.

Finally, if you aren't going to make a constructive contribution to this forum, please stay out!

 

well i saw a scrambler X out at some atv drags last weekend and it must of had some kind of big bore kit in it cuz it was wipin its ase with every1. and yes it was the 4 stroke one. there were 30 classes and i bet this guy was in at least 15 of em. anyways he was beatin tons of guys, 440 (maybe more)ex's, an fx400, 250r's, raptors and ds's. everything! it was pretty sweet. there was a lot of fast polaris's out there.

 

Mike,
I take it you were talking to someone who deleted their message? Dontknowcrap? I was surprised as well when I heard they did not change the clutching at all. I would really like to see one with a properly tuned clutch. I Bet this would be a great kit for a Sportsman. It has to produce a ton of torque.

 

What is "properly clutched?" I just haven't messed with it much yet but I'm learning. I love engagement of my green spring, it's a perfect rpm. Now, what will weights do, change the clamping force? How can I get it to be torquier and accelerate faster without losing top end. Do I change the secondary for that? I want to keep the same engagement RPm and top end but have more umph in the middle. Any expert help would be appreciated.

 

Here is why we do not change clutching.On a big bore/stroker FOUR STROKE you make so much torque that you run through the rpm range alot faster.This also makes the clutch engage quicker and shift up faster.We then can run a big cam to get more top end.On a WARRIOR 446cc kit we have to go up 3 teeth on the front sproket so it dosn't run through the rpm to quickly.On most TWO STROKES you have to get the rpms up before engaging the clutch to be in the right power band.