I put a Scrambler/H.O. cam in my son's 425 Xpedition. It pulls much stronger but has little appreciable difference in top speed, about 52. My new H.O. will do 65, and he wants more speed.
Is there a rev limiter and can it be disabled
without blowing something up--like the crank or a piston?
As it is shaft drive we can't change gear ratios other than bigger tires/wheels, which we don't want or need for the kind of riding we do.
A K&N and a Rick Ritter muffler are on the
x-mas list, but a little insight into this rpm limiter could really help my 80 pound 12 year old go too fast and blow the motor. Any help in this regard would be appreciated. Thanks.
Silly Later,,,, Fourlix

 

Hey fourlix~
I'm not a father and I don't want to sound like one...but do you think your 12 year old needs to be going more than 52 mph??? For his size, the machine is probably a little big for him. I think he has a big enough machine for the next 4 years! I would much rather see a slightly dissapointed 12 year old than a dead 12 year old. Things seem to happen a lot faster at 60 mph than at 50mph. I think your son would have a little trouble controlling the machine. Making the machine faster would just give you trouble. My two cents. Dang, I do sound like a parent!!

 

You are absolutely right WIscrambler. He is supposed to be riding something like a Yamaha Breeze at this stage. His 425 EXP already kicks ***. It is way too much bike for him....Till you see him ride. I feel like I need to keep him on this as long as possible before he needs a Raptor or at least a 400 EX. He skis the same way, since he was 3.
I don't know where he gets it. I am not a talented rider, I am a much better mechanic/engineer than a rider, but I've been around talent because I was a good wrench, and he's got it. He is still only 4'9", smallest kid in his 7th grade class.
His mom hates motorcycles, even dirtbikes, but that may be where this kind of talent should be directed. But Sport Quads are a little easier on the body than MXers, and if he keeps going the way he's going, then a Sport Quad is probably in his future. Can I hold him off till he's 14?
He's careful and fast, only rolled it twice, bailed both times, unscratched, always wears his cool O'Neil full coverage MX helmet. I think interests like this are a huge advantage in a boys life, and being good at something is such a wonderful thing.
But okay, No Raptor!!
Silly Later,,,,Fourlix

 

Hey fourlix~
I'm only 19 years old, so I'm not too far out of that beginning stage! I actually started out riding a Yamaha Breeze when I was 9! I rode that machine fast(being 9, I thought it was fast)! About age 13, I graduated to a 250 trailboss. That machine felt huge compared to the breeze! I also thought that machine was fast! Once I turned 16, I got the scrambler and that is still a great machine for me today. It sounds like your son can handle the machine fine, and rolling it twice may have been from the lack of experience. I, too, would try to keep him on the 425 as long as possible. If he does have an outstanding talent, maybe dirtbikes would be a better option for him...but an ATV as way more versitile and practical. Just wait until he starts to drive...start him on a cavalier and just wait until he buys a camaro!

 

fourlix,
From what I have been told by the dealers ther is not a rev limiter on the Polaris bikes. In the manual it does not say anything about a rev limiter either. I think that a bigger carb may help it rev higher with the exhaust. But I do not know if the crank will do like the 500 crank. The 500 crank does not like the aftermarket cams that let the motor turn over 7000 rpm.

 

Yeah. WIScrambler is right.
I'm 18, not a bad rider (have been riding bikes since age 8, ATVs since july...), but I rode a friend's Xplorer 400, at top speed (like 50mph), I had more adrenaline pumping than on my shee running 70-75mph. The Xplorer bounced from side to side, and I admit letting off the throttle several times (shame on me ). It's not really a matter of power or size...just that if he wants to ride fast, GET HIM A FAST MACHINE. A 400EX (or any sports quad, for that matter) will be much safer than an Xpedition (or whatever utility quad). I know it's way more expensive, but it would be safer for HIM.
By fast machine I mean machine that was mant to be fast.
BTW what's the use of waiting for him to turn 14? waiting for him to crash and get hurt? I'm sure (I have no doubt about it) that he isn't strong enough to handle a 700lbs quad. Get him a Blaster, 300EX (or 400EX, they're slow anyway ). He'll probably have more fun.