How do you know it's time?

[bnt55]

How do i know when my KDx needs a top end done to it? Everyone I talk to compares a top end to tripping over a log (a no brainer) but noone has told me why they needed it done. What are the symptoms I should look for...cause I think I am heading towards one.

Bill

 

[kdxjr]

power lose, take it to a local shop and have the compression tested.
If it runs good leave it alone..

 

[Wharf Rat]

From what I gather either the compression is low or it is wintertime. That is how you tell on a KDX I guess.

On MX bikes it is far more frequent.

If you get a guage with the right size attachment, you can do the compression test yourself. Very easy. It is worth buying the stuff and then you have it to use. Compression is kind of necessary in an engine, if you know what I mean.

 

[JasonWho]

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[keith500r]

signs of needing a top end are your bike getting harder and harder to kickstart as time goes on and eventually it will only start by push start if you let it go that far.

 

[KdxChode]

What a pain in the arse!! Back in the day my old cr125 had a built in indicator. When the motor seized and quit running it was time for a top-end. Happened one or two times a year.

 

[mprest4]

loss of power/hard to start

if you let it go too long you run the risk of shattering a piston,

but the kdx has a very long life between pistons.

 

[yzeater]

How long has it been since you've done a top end?

 

[bnt55]

The bike I purchased not long ago is a 92 and according to the previous owner there has never been a top end performed. It runs ok right now, but I noticed it "missing" while I am at half throttle in the upper gears, it also dies by itself while idling sometimes (prob carb)

 

[kdxtodd]

I have over 600 hours roughly on my 96 kdx since I brought it 8 months ago. Its only lost a little power, but I think its the powervalve. Im really surprised its gone that long. I do a lot of fast, wound out trail riding and mx. Its been a really reliable bike. I think the right type of oil(ratio), and jetting extend top end life.

 

[WoWman]

I've had my KDX for 4 years now, on 2nd piston. That was done about 5 years ago, she still runs good though ie. no smoke, good compression.

I know for a fact that the powervalve is either stripped or extremely gummed up, because this thing has now power until way up in the revs. But then it hauls ass. :D

I would open the top end up, but I'm afraid of what I could find...

 

[pheanix]

What are good compression figures for KDX200 (-97)?

 

[70 marlin]

sounds like it's time. with this bike being new to you and the old owner said he never did one. I'd pull the jug and do a ring end gap measurement, check the condition of the cylinder plating and do the power valve service. also would be a good time to ship it off to mr gorr or jeff fredette for some porting! but most people do this service during the winter. so do a pressure test and just ride it till winter unless your test comes up very low. good luck