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Hello peoples. I bought an 07 KXF 250 about six months ago with "low" hours on it. Its my first bike so I'm kind of clueless with the major maintenance schedule. I dont know for sure that the bike has the stock chain and tires on it so maybe that gives some idea of usage. I put approximately 30 hours on the bike this past summer.

My question is... at what point should I be cracking the cylinder open? What is replaced during this interval and is there anything else major I should be watching for?

I've already checked valve clearances multiple times and all was good. I have alot of experience building high hp turbo cars but this is my first run at a bike motor.

Any help would be greatly appreciated.

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I'd recommend checking the valves every 15 hours if you're not racing. If you are a racer, do it after each moto to be safe. As for opening the cylinder, I'd wait until you are having compression problems and the valves can be ruled out. A leakdown test will tell you this.

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The most important thing you can do is clean the air filter after every ride. It will help keep those valves in spec for a long time!

I change the oil every 3-5 hours on my bike, some people think they can go longer than that, but I prefer not to risk it.

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Ok heres my view and yes it is overkill but it will help ensure it lasts longer..

If you have the money this winter replace everything..

i.e. crank, valves, piston, main bearings, & cam chain..

You can send the head to mxtime.com for around ~450 dollars dave will replace the valves, seals, & springs along with full decarbon of head and cut the valve seats.. When you get it back it will be ready to slap on with nothing else needed to be cheacked..

If you choose dave tell him Adam from La Porte sent you.. BTW he's the only person I let touch my head.. BTW if you plan on doing the valves your self.. You cannot lap the valves and the seats must be cut right..

This way you know all parts that can fail with an end result of catastrophic failure has been replaced..

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I've been using Belray Thumper oil every 10 hours so far and cleaning filters every ride. I just did a compression test and leak down. Results were 97psi after 5 kicks and leak down was approx 4%.

What is the reason for not being able to lap the valves?

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The valve seats and valve material are very hard to mate together with just lapping compound. As the valves wear, they form a wear pattern into the valve seats that is not necessarily concentric. A valve seat cutter will ensure a perfect fit with new valves. In your case, I'd say that your valves are in great shape and there's no need to change any major components in your valvetrain.

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If you dont already have ....get a hour meter so you can keep true track of hours on the bike....Sounds like its time to pull it apart and check everything....More than likely you will need to replace the piston.....But check everything,cylinder,valves and crank....Winter is a great time to freshen it up and be ready for spring.........good luck on your project.....

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Where is a good place to get an hourmeter and what could I expect to pay?

*edit* I just downloaded a service manual for my bike from pdftown.com. I'll bet there's one for your bike there too.

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The valve seats and valve material are very hard to mate together with just lapping compound. As the valves wear, they form a wear pattern into the valve seats that is not necessarily concentric. A valve seat cutter will ensure a perfect fit with new valves. In your case, I'd say that your valves are in great shape and there's no need to change any major components in your valvetrain.

These valved are coated with a nitride coating that reduces wear and increases valve life.. if you lap the valves especialy the titanium valve you will probably reduce the valve life by 90% on the SS valve lapping will probably more towards 50-60% life.. Lapping on these motors are a NO NO.. the seat cut is to ensure that like you said a new valve mates correctly to its design..

Like I said in my erlier post that it maybe overkill but at 30hrs and who knows how many from the previos owner.. It would be a justifiable equasion to replace the valves

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Thanks for the info guys.

Just to be clear...,when replacing the piston and ring, it is maditory to replate the cylinder. Correct?

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Thanks for the info guys.

Just to be clear...,when replacing the piston and ring, it is maditory to replate the cylinder. Correct?

No I don't think so. The manual says that if there is no visible damage to the plating and the cylinder does not measure outside the service limits then it is ok. I rebuilt my 06 and it was fine.

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