Preventative Motor Maintenance KXF250

[PanamaJason]

I just bought a 2007 KFX250 with:
a pro circuit titanium full exhaust,
boyesen water pump,
an aftermarket cam (not sure of type),
an adjustable external fuel valve on the carb (not the idle screw),
and an aftermarket air intake filter.
The bike was raced for one year by a professional, but I have no interest in racing it now. I will be using it for transportation. It was ridden at sea-level but I will be riding it from 5000ft-12000ft elevation. I haven't taken above 7000ft yet and it runs great. However, I ride from trails to highway and I need to have more topend because the motor revs high at 50mph in 5th gear. I am looking to extend the life of the motor. I am not looking to make it any faster, I just want to last a long time. Is there a way to electronically detune the motor or would it be better to change the front and/or rear sprockets in order to lower the RPMs? I would also like to put 50-50 enduro tires on it. Any suggestions?
Thanks, Jason

 

[IndyMX]

I'd consider selling it, and getting something more suited to your needs..

Something like a Dual Sport would probably be better.

The bike you have is a high strung race bike. Not exactly suited for use as a daily driver.

 

[PanamaJason]

Unfortunately down here in Panama (Republic of, not Florida), I have to work with what's available to me. Any good Dual Sport is at least $10k with only Yamaha, Kawasaki and KTM available. I know I bought a race bike, which is why I thought I would post on this site. I am looking to avoid potential failure issues, valve train timing chain, etc. Maybe I should have asked...
What daily/hourly motor maintenance should I be most concerned with? Over the last 50 hours of use, the kxf bike has lost zero coolant and only a tiny bit of oil. It is my first 4 stroke motocross, I have had a few 2 stroke KTM (300EXC). I am looking for any tips for gearing. I would like higher mph lower rpm. I ride mostly wideopen dirt roads or fire roads.

 

[Patman]

Let me get this straight you bought a used race bike from a "pro" racer so it's got to have some serious use on it, you don't know what's been done as far as service to the engine but you have racked up an additional 50 hours with no problems? That being the case you needs to seriously look at a complere tear-down, inspection and rebuild. The last thing you want on the highway is an engine melt down that leaves you sliding across the pavement with a chance to get run over while you are doing it. Doesn't sound like what you want to do? To bad you cought a race bike and they take significantly more love than say a XR250/400 or DR250/400 which sound like they would have been a significantly better choice for your use. If you are the mechanical type get a factory service manual and get busy if not find a good shop to do the work for you. If I recall those bikes were not known for long life of some internal pieces.

 

[sharky243]

The only way to change the RPM's of the engine is to re-gear it. Put a smaller sprocket on the rear rim and a larger sprocket on the counter shaft off the engine. This will bring the RPM's down. The cams that are in it were probably chosen for mid to top end power. You'd be better off with the stock cams. I would definitly replace the piston, rings, cam chain, and have a real good look at the valves. You might be lucky with the bottom end, but i would check it out. A "retired" race bike usually has had the crap kicked out of it. Haveing said that, the 07' KX250F's were a fairly reliable bike as long as the maintainance was kept up on them.