2007-2009 Kfx50 Big Bore

[airmobile101]

Well, we had our last race of the season and I wanted it done ASAP before it gets too cold and before we start our 2-smoker project.

1st impression, well worth it. I think we are at 86cc now. Had a tad bit of issues with jetting, but got it nailed down now. Everything pretty much went smooth. I'll get some numbers for yea in a few days when I put a accelerometer on it.

It was a good upgrade since it costed us a total of maybe $170.00 plus shipping. It included the Big valve head.

Now, I wonder if I can somehow slap a KFX90 crank in it. That should be us close to a 110cc.:D

[airmobile101]

Ok, with a15/32 sprocket combo, I was only able to get 25.9 MPH. Now keep in mind thats one tooth less than stock with smaller rear wheels than a 90 and stock 50 wheels.

Now, I swapped the gears around to a 19/28 combo and was able to only achieve around 28 mph.

Then, I did the old faithful combo of 17/28 and got some good results. I got it up to 30.9 mph, but I noticed the quad wasn't winding out. So that tells me I need to make my variator rollers a tad bit heavier. I'm pretty sure I'm not getting the full travel on my belt. So I bet the 19/28 combo would work alot better also with a little more variator weight testing.

My overall goal is for it to only go around 30mph anyways. But I need it to get there quick as possible for the type of racing we do:D

All the testing is done with 21.5 total grams of roller weights.