90cc full engine mod vs 85cc bike engine

[bear dad]

i need to find out if a mod 90 atv engine could beet a 85cc dirtbike engine such as a cr85. my son is always complaning that his predator doesn't have enough power. he wants me to put a 250 bike engine in his pred,but then he wont be able to race. please i need a very fast engine thats keeps his pred legal. THANKS

[newnick]

Send it to Billy at WRHracing, your son should be satiisfied with the power afterwards.

[LT80]

Or Moore Racing.:eek2: :D :D

[BradLoomis]

I have never seen a modded 90cc CVT motor beat a stock/modded CR,YZ,KX,KTM 80-90 dirt bike motor on the track or on a dyno. The are just two totally different style engines.

Having said that... I have seen many CVT bikes beat Shifter bikes because of the riders ability, not because of the power. Alot of people believe that the reason other kids win is they must have more power. That happens maybe only 10 percent of the time IMO. Two equal riders, one on a quality 90cc shifter bike the other on a quality 200cc Blaster, the shifter will win most of the time because it is a better handling bike and better over all package.

Now you also said you want to keep the Predator legal which in most cases means it must stay a CVT and under 90cc's. We race Predators and like them alot, but they don't compete with a quality shifter quad. If you put a bike motor in your Predator, the chassis won't be able to take it and your kid will probably get hurt worse because of the extra power. These bikes don't even like being raced with a modded CVT in it because of the cheap steel frame and single A-arms and such.

My suggestion is find out your race rules and pick a class, if it is CVT... send your motor to Billy at WRH or Jack at Moore Racing or a few others that understand the CVT's well, you won't be dissapointed.

Just my thoughts.

[bear dad]

thanks bradloomis for your answer to my question. the problem is still what to do,we live in north idaho and there is no place to race close to home except spoakane wa. and now they stoped racing youth quads for lack of riders. i built a large track on my land so we can race bikes,quads, and in winter sleds(snowmobile). my sons practic all the time and realy wants to race,so we are trying to sell our house to move to GA,orFl and i dont no the ruls for racing there. one of my sons likes mx and the others like offroad racing (gncc).the bigest problem we have i a lack of bottom end power thats why i have been looking at different engins. I thought if the engine is under 90cc it didn't mater what is was to race. thanks again PS i built a church in woodland wa. and realy liked the place,the best part of that job was the 48 pound king i caught up the river.

[Livin4Real]

GA or FL, nice to visit. Heck move to Indy, that way your centrally located and can hit a bunch of tracks :D There are plenty of folks that can give you a hand with a better setup on here, just depends on how much you want to spend :D

[QuadJunkies]

Originally posted by bear dad
thanks bradloomis for your answer to my question. the problem is still what to do,we live in north idaho and there is no place to race close to home except spoakane wa. and now they stoped racing youth quads for lack of riders. i built a large track on my land so we can race bikes,quads, and in winter sleds(snowmobile). my sons practic all the time and realy wants to race,so we are trying to sell our house to move to GA,orFl and i dont no the ruls for racing there. one of my sons likes mx and the others like offroad racing (gncc).the bigest problem we have i a lack of bottom end power thats why i have been looking at different engins. I thought if the engine is under 90cc it didn't mater what is was to race. thanks again PS i built a church in woodland wa. and realy liked the place,the best part of that job was the 48 pound king i caught up the river.

We too are from Idaho ,we have minis in the Boise area,but they arent abundant right now. That SUCKS that minis arent racing in Spokane cause we as going to hit a series up the in the spring:(

We have a built WRH motor and I can tell you 1st hand he can find you hidden power in your mini:devil:

Have you followed any of the WORCs series yet?
If you have some free time to make the drive, I can give you track info for Idaho.

Tina

[newnick]

Brad is right all the way around. What you didn't mention was your sons age and size. If he's old enough to move up to a bigger quad like a 300ex or a Blaster that would make more sense than hopping his up. If he's still to young or small you can do the Pred. But keep in mind he'll need more than just a powerful motor. The suspension and frame will need to be done first so it will handle all the stress of going faster and flying higher.

[QuadJunkies]

Originally posted by newnick
The suspension and frame will need to be done first so it will handle all the stress of going faster and flying higher.


lol Trust me.. Were finding that out now... lol

I agree as well.

[markvette]

like most have already said here. it all depends on where you race. north alabama has a quad assc. that has a 90cc and under class and a supermini class with a 105cc limit. all 3 texas assc. have a 96cc limit, not sure about florida. what i would do is build a motor with a 45mm crank. with a 50mm cylinder you will be at 89cc and national legal. then you could put on a 52 or 54 mm cylinder and raise the cc if you raced somewhere that has a higher cc limit. but on any og these motors porting is the secret, putting a bigger stock cylinder will show very little power increase if any but also again everything has to work together to get max power, cc, clutch, variater and suspension. my son runs a 110cc stroker motor, 48mm crank with 54mm cylinder. i can put a 50mm cylinder on and have 94cc and be legal in texas or a 52mm cylinder and be about 103cc and be legal in alabama. also with the cylinder changes i have to do clutch and variater tuning as each cylinder has a different power band.

Mark

[bear dad]

I'd like to thank everyone again for the info, we are starting to figure out what we want to do. I looked at the WRH web site and i think thats the way to go, with k-fab sup parts. the info about my boys are 7 year old 4'8" at 104 pounds and 9 year old at 5'2" and 126 pounds. these are the main two that want a future in atv racing, the other likes quads but wants to be like dad and ride bikes.both boys are great shap and are extremely strong. I no all about how bad the frames are on the little predator i weld it up almost every other time they ride. there size is why i question the stock moter being moded up,wondering if it could take them to the level they want to race at. THANKS AGAIN

[bstuart]

Wow - looks to me like you need to forget racing, get those boys enrolled to football camp. lol Those are some linebacker stats.

[newnick]

Looks like their both on the edge of being to big to invest all the cash it takes to build up a mini.