KDXRIDER.NET

Some of these recent threads have me thinking - How often do you guys replace your top ends? And, how many top ends do you normally go through before you address the connecting rod or crank bearings?
I know that our KDX's have very stout engines, and they seem to require much less service, both in terms of top end and crank services, than most other higher strung 2 strokes of similar displacements. This is one of the reasons that I love them!
I would guess that the toughest part of this question is that the "motor time" would only ba an approximation for most of us, and bike use varies so much from one person to another. I ride my bike about 2-3 hours a week, but I ride it pretty hard. Given that kind of service, I would expect to do a top end every year (whether it needs it or not! LOL!), and a crank service every 3-4 years. Am I way off?

i put a new piston in my bike about every 6 years!!!!!! i do a top end when my compression get to 155-160 psi.

That's about right....

An hourmeter is a great way to keep track of major maintenance without any wondering if you're past due. I got one of the hardline meters for $35. Trans oil and spark plugs every 10hrs, bearings every 50, top end every 100.

Totally depends on how you ride, for example in the winter months when it's snocross, you can have the engine wide open revved all the way out for 4-6 minutes at a time. (You should see the carb ice up!) but in th summer on the trails you'll be lugging it alot more.

Just a thought.

I guess that I am way off in my estimates... My '04 is still on its original top end and crank, though (as far as I can tell), and I have only owned the bike for 10 months or so... It would probably be a safe approach to replace the top end and service the crank now...

What do you guys mean by "service the crank"?

Service the crank = Replace the connecting rod, lower end needle bearing, and pin. It also should include main bearings and seals.

That's what I was afraid you would say.....
You have to split the case to do that right???

I see no need to service the crank unless it is out of spec

You have to split the case to do that right???

Yup

I'm on year three with my top end. I've got about 350 hours on it, conservatively. I ride mostly single track and push it pretty hard.

Only twice in 36 years of bike ownership have I opted to go into the bottom end of a 2 stroke. On the first occasion it turned out to be a waste of money because of the condition of the rest of the bike. The second was the hybrid I'm on now. I had that job done by shop I trust completely. I'm pretty sure that by the time I wear out this lower end the rest of the bike will be junk as well. I'll be putting a top end in it this winter. I don't expect to be owning the bike for more than another year, though.