2007 kfx 50 cdi

[cudon12979]

Will a crf 50 cdi box interchange with the kfx? So far I've put a pro circuit pipe, uni filter, 17 front sprocket and 28 rear sprocket. On this kfx, my son would like to go a little faster. Oh, it has also been ported and polished. Right now top speed is around 23 to 24 m.p.h. Any help or ideas would be greatly appreciated.

[airmobile101]

http://www.exriders.com/vbb/showthread.php?s=&threadid=410780

[airmobile101]

To answer your question, no it won't.

[cudon12979]

Thank you for your help. I tried removing the weights in the variator and it made it a lot slower. I reinstalled all six weights and it went back to normal. By the way your sons kfx looks awesome.

[airmobile101]

Originally posted by cudon12979
Thank you for your help. I tried removing the weights in the variator and it made it a lot slower. I reinstalled all six weights and it went back to normal. By the way your sons kfx looks awesome.
You have to consider a few options here. The lighter roller weights help with the acceleration but sacrifce the top end. Its a trade off. Less weight equals a higher reving engine with faster acceleration, more weight equals a less reving engine, but a higher top end. The question is, how much did you remove? If you removed too much, the weights might not be pressing on the sheeve to get the full travel of the variator and the belt. Now, that can also be because your not running a aftermarket cdi. 7500 RPMS is all your gonna get with the stocker cdi.

[airmobile101]

Just one little bit of info you need. If you run the quad rollers too light. You will suck the carb bowl dry!!!!!!!!!!!!!!!!!! Why???? Because the quad spends more time in a higher RPM range and the flow rate can't compensate for the fuel being sucked out of the fuel bowl! lol :D

[burkcs]

Originally posted by airmobile101
You have to consider a few options here. The lighter roller weights help with the acceleration but sacrifce the top end. Its a trade off. Less weight equals a higher reving engine with faster acceleration, more weight equals a less reving engine, but a higher top end. The question is, how much did you remove? If you removed too much, the weights might not be pressing on the sheeve to get the full travel of the variator and the belt. Now, that can also be because your not running a aftermarket cdi. 7500 RPMS is all your gonna get with the stocker cdi.

I removed three of the six stock rollers and it slowed the bike down to like 3mph. I put all six rollers back in and the bike is back to normal speed. Do I need the aftermarket CDI to take advantage of removing three rollers?

[LT80]

NO....You need aftermarket rollers to get to the ideal weight (which you are no where near at this point).
You need the roller weight of 4-5 rollers to experiment with.
Example:: Rollers are 10 grams (approx) your going to 30 grams which is too little. You're needing to try diferent weights. ie: 35-40-45-50 (grams), etc.
So, try 4 and 5 rollers and see what helps the most. Then you can get aftermarket rollers.

[airmobile101]

Exactly what LT80 said. We ran our 50 at 21-30 grams depending on what mods we had at the time. We had to recalibrate our cvt every time we added or removed a mod. Now, since we installed the 90cc kit, we are damn near back to our original weight in our cvt. Odd isn't it???? You want to lighten it,but not where you lose alot of top speed,but that might be acceptable if you want it to accelerate quicker.

[airmobile101]

Originally posted by burkcs
I removed three of the six stock rollers and it slowed the bike down to like 3mph. I put all six rollers back in and the bike is back to normal speed. Do I need the aftermarket CDI to take advantage of removing three rollers?
Ok, I think I might have read this wrong. Is 3mph the top speed????? If so, that sounds like you still have the wedding band restrictor in there.lol

[burkcs]

Originally posted by airmobile101
Ok, I think I might have read this wrong. Is 3mph the top speed????? If so, that sounds like you still have the wedding band restrictor in there.lol

All restrictors have been removed. The bike is all stock other then removing the cork from the muffler.

Top speed was like three mph with only three of the stock rollers.

I am looking to get more top speed. This doesn't appear to be the right mod for me at this time.

What are the best mods for top speed?

[airmobile101]

There is something not right if your only getting 3 mph tops out of it with three rollers. But to answer your question, put a 17 t front and a 28t rear sprocket for a few extra mph.

[burkcs]

Not certain what could be wrong. You remove three rollers and reinstall.

Where's the best place to get the sprockets you recommended. I would imagine they are hard to come by for the KFX50.

[airmobile101]

Try Rebel gears.com

[cudon12979]

Airmobile is right, rebel gears has the sprockets you're looking for. But if that ring is still in, it'll slow you down to a crawl.

[cudon12979]

Did you reinstall the variator the right way. and not backwards?

[airmobile101]

Thats what I dont understand??????