Just wondering something. I bought and installed the RCR Stage 1 Low/Midrange Kit for my 2000 TrailBlazer. I can definately tell the differance, for sure. My first question is how much horsepower is this machine making now? Its the only thing I have done to it.
Second question is this. What makes a quad fast? I mean looking on paper, you'd think (and I may be way way way off here) that a slightly modified TrailBlazer would at least be able to accelerate neck to neck with a stock Scrambler 500 at least till the small 250 runs outta RPMS. The reason I say this is because on both HPD and Hotseats websites they quote Stock TrailBlazer HP at 22. Both give an estimate of HP after Modding right around 30, and this is just with a pipe, no airbox changes or filter changes. Now granted I really don't know for sure what the RCR pipe and freeflowing airbox boosts HP up to, but I would imagine it can't be too far off of HPD and Hotseats advertised specs. So anyway. Hotseat states that a Scrambler 500 4 x 4 stock HP is 38. At 541 pounds Dry weight it gives it 1 HP to 14.26 lbs. Now theoretically if I am making 30 HP (which I suspect could be making a tad more with the free flowing air box I now have, not sure though) now with my modded Trailblazer at 440 lbs dry weight, it comes to 1 HP to 14.66 lbs. Not too far off right? But I honestly don't think I can accelerate from a stand still and hang with a Scrambler for any given amount of space. Why is this? Gearing? How the engine makes its HP? Does the Scrambler make Peak HP before the modded TB? I just don't know. I haven't raced any Scramblers with this kit on, but I have 2 buds that have Scramblers (a 500 and a 400) and those things are FAST. jdediks 400 I know screams now. I am pretty sure I don't stand a chance (especially against his modded Scrambler 400). Thoughts? Am I screwed up in my logic?
Third and final question. Now that I have put the RCR Stage 1 kit on, I have an enormous amount of wheel spin. BIG time wheel spin. Today I was messing around in my yard (pretty thick turf). I gunned it from a dead stop it lurched up a bit and then just tore 2 grooves in the yard. (Wife wasn't happy) Hehe. Same with pavement, this thing spins like mad. Tires are only 2 months old, proper tire pressure. I am thinking of dropping a few teeth on the rear sprocket. Will this help? Or would a rear tire change be in order now? I'd like to keep as much low end grunt as possible. Thanks for your opinions, help, flames, etc.

 

PaPaul,

I think the key to the whole situation is efficency. Sure it makes 30 hp at the crank, but how many ponies are making it to the rear wheels? With a roller clutch there is less lost horsepower than with the standard buttons/helix. It can be said that some machines can lose up to a third of their horsepower just operating the drive system. Porting the motor, milling the head, adding a larger carb, adding a roller clutch and running a straight K&N filter will help even the odds slightly.

The second consideration is torque. A lightweight 250 motor using no counterbalancer won't have nearly as much torque as a 500 four stroke. Torque also figures into acceleration along with horsepower.

You also have to figure in the type of motor you have. A 2-stroke piston port isn't going to run nearly as strong as a 2-stroke reed valved motor of the same size.

Gearing is another matter. You are lucky that you have the 2000 model. Changing gearing isn't too bad. I'd go up one tooth on the front (countershaft) sprocket to a 12 tooth. You may lose a little quickness, but you will gain in top speed. The other option is to go down two teeth on the back to a 36T.

With all of the gearing and engine mods that are available I can forsee you being able to keep up with a stock Scrambler, but as soon as someone modifies their 400 with a pipe, you'll be left in the weeds again. It's a sad fact, but true.

 

True I will never keep up with a modded 400, I know that. It just intrigued me after thinking about the Topic for a bit. I just couldn't come to a good reason. The torque explanation makes a lot of sense. Thanks for your explanations and insight.
BTW, Do you ever come to Potter County to ride?

 

PaPaul,

If you mean the Susquahannock trail, I've been there once and am planning to go there again by the end of the month. I'm off on vacation from August 19th to Sept 2. Celeste and I are planning to ride it. I was in a bit of a hurry the last time I rode it and would like to enjoy the scenery this time and ride all of the trails, not just the outer loop. Let me know if you want to go.

 

Mike, Yes that is the Trail. I like it alot. Its not very difficult by any means, but still fun none the less. I will be in Florida until August 25th. If you plan to ride the Trail between August 27th and August 29th let me know. I am always looking for people to ride with. I have a few guys here at work that love to ride as often as possible too. Just gimme a heads up and we'll ride.

 

The HP ratings that everyone uses are all over the place. It's like comparing apples to oranges. Most of the aftermarket speed shops are using crank or flywheel ratings for hp. It's a good "bench test" gauge for them when testing against a stock engine to see how their product can improve the power.

But, to us end-users it sometimes does not mean that much, depending on how the machine is set up to get the maximum amount of hp to the rear wheels.

A good example of this is the "so-called" stock hp rating of 32 hp tagged on the SP500 (non-HO) engine. My, my, if there was anywhere near that to the rear rubber it would be a monster. In reality it only puts out 18-19 rear wheel hp. Quite a difference.

I don't fault Polaris, since all the manufacturers and speed shops generally use the higher numbers, it's ad hype . . . sounds better, and it sells more parts. You see, they can't tell you how much "you" will actually get on "your" machine, because they don't have "your entire setup to gauge it against.

For most of us, the best way that I know is against the clock and against a know stock machine of the same type.

Sure a rear wheel dyno would be great, but how many of us have the availability of one to take a before and after testing session. I might add, that the cost to do this could easily be more than the cost of the modification.

The only source I know of that has been doing rear wheel dyno tests on stock and modified equipment on a regular basis is ATV Sport mag. Dirty Wheels and ATVC generally slide around this issue and don't want to take the time or spend the $$$ to do the testing that would get you much close to real world results.

To answer you question about modifying your engine to compete with 400's . . . it's a waste of $$$$. Buy a 400. You can build all you want, but you will not be ablt to touch the 400. Against another stock machine, like your, sure it's quicker and faster. Maybe for a few yeards in a drag race, but even a stock 400 will kill you on top end.

www.godigital-design.com/schultzmotorsports

 

Jack
would u buy a sp700? rumor has it that it will be around 50hp at the primary clutch. that means atleast 32rwhp. it will fly


later
jon

 

Jack it wasn't really a question on how do I build the 250 to beat a 400. I knew the answer to that already. The main question was considering HP and weight, why DOESN'T the modified 250 come near a stocker 400 or 500. What makes a fast machine fast. I think Mike explained a lot in his post, torque. I neve considered torque. Thanks guys.

 

I have seen some very fast 250cc machines. I ride with a modified Quadracer that I'm sure would have no trouble with a 400ex and I have seen a modified 250R easily outrun a Banshee. This leads me to believe the problems with the trailblazer would have to be mainly weight and (like Mike said) piston port vs. reed valve motors.