After how many hrs do you typically do a rebuild?

[Bitteeinit]

Two questions:

1-How often (after how many hours) do you split open the topend (to check the piston or clean the KIPS)?

2-How often (after how many hours) do you usually put in a new piston set?


I've heard around 100 hours for #2... I'm currently at 40 hours on my piston and have done neither. I'm opening up the bike now to change a few seals (waterpump mainly, but others as per this thread: http://www.kdxrider.net/forums/viewtopi ... 77&t=16972). Also going to change both wheel bearings (rear failed on me the last ride... Not fun. Felt like I had a broom stick for a swingarm). Obviously I'll have a look at the piston to see what condition it's in while I'm at it, but was wondering what rule of thumb others followed in regards to these two questions.

[cornishwrecker220]

If it ain't broke then don't try to fix it!

However if you maintain your bike well with quality oils & regular servicing paying special attention to the air filter & oil then there is no reason why your kdx shouldn't give you years of trouble free fun... They are tough as old boots...if you strip the top end on a new ownership bike & inspect/clean everything .. Pop in a new top end ( this can give a good idea as to what the bottom end may be like ) & go from there.... Parts are cheaper than a four stroke so just go the whole hog & rebuild the lot !

[Bitteeinit]

Are you saying I should wait for my piston to seize...? I'm not asking about the lifespan of the bike in general, but rather how often I should be checking/changing my piston. Is 100 hours a good rough estimate? Obviously I'd check it if I started losing top-end and all that. But from what I gather, most seem to change them every 90-120 hours. Obviously racers would change much more often, but for the casual rider... I change my oil regularly, though not religiously (every few hours... Probably ~5-6 or so). I change my filter a bit more often than that.

[cornishwrecker220]

A compression check will tell you if the rings need replacing...( the workshop manual will give you the specs you need ) you can rebuild & service the top end when everything is apart.

The kdx is not as highly strung like many other competition 2 strokes on the market & a top end can last for years before needing any work ... I've owned my 220 since 2008 & only removed the original piston after covering 7000 miles...it was in great shape considering all the horror stories of the OE piston exploding...I've been running a wossoner piston for the last 2 years & when the motor was stripped & rebuilt early this year, it never needed to be replaced as it looked like new without any marks whatsoever ..I did fit new rings as it would be silly not to given the price ..

So my advice, & for your piece of mind is to do a compression check & go from there.

[kawagumby]

I change the piston and rings when the piston starts getting louder (piston slap). When I used to ride 2-3 times a week that would mean a piston change every 1 1/2 to 2 years. I never just change the rings out anymore, the compression has always stayed up until the piston wear dictates change.

[Bitteeinit]

Wow, that's impressive... Thanks for the advice. I guess I don't need to waste money on a piston right away... Do you know roughly how many hours you were typically at after 1 1/2-2 years kawagumby? I tend to do long rides (3-8 hours) and ride around 1-2 times/week so I rack up the hours quick.

[cornishwrecker220]

The secret of longevity is to always run your 2 stroke on a good quality 2 stroke oil & clean & oil your air filter on a regular basis.

Any crap sucked in through your air filter will make its way straight into your top end, not only marking your barrel & piston, but drawn down & into the bottom end too damaging the big end & main bearings....its always a good idea not to let your 2 stroke sit idle for any length of time as condensation can form inside the motor which will cause the main bearings to rust, also over time crank seals can harden & fuel will go off....it doesn't hurt to fire the bike up for a few minutes, even better if you can ride it .

I roughly worked out that approximately 25 hours equals to 600 miles ( I once owned a ktm & used its hour meter to equate the mileage ) as I still ride the same tracks & trails I have stuck with these readings & service my kdx by them accordingly as I have now fitted a hour meter & removed my odometer.

[MikeNZ]

Yeah all good advice these things can go along way between major maint I did 100 hours on mine not sure how many hours if had already done when I got it. Stripped it down was still all within original specs. So put new top end in anyway now don't plan on going there again for probably 200 hours unless something obvious happens. 2005 kdx 200. Cheers

[Bitteeinit]

Thanks guys.