93 kdx 200 wont start ......grrrrrr

[like-to-ride]

ok just like to say hi to all been reading the forum and was on here before. So here is my problem my son has kdx 200 while he was riding it just stopped running so he had to push bike back home. I figured bad plug so I changed plug to new and checked it see if was getting spark and it was (what is good spark) I get spark every kick. Thought that maybe carb plugged so took it apart cleaned and put back together and still no start. thought maybe kill switch causing problem but that works. I'm lost of what to do or check I really don't want to take it to shop cause its expensive and probably something dumb ...so kdx nuts please help thx :bang:

 

[dirt bike dave]

Does it have any compression? If not, could be a hole in the piston.

If it has good compression, the key that holes the flywheel in place may have sheared. If this happens, you get good spark, but at the wrong time.

Is it getting gas? Could be a clogged screen in the pet(c*ock or a clogged breather hose to the gas cap.

If the compression is low, it sounds like it is time to disassemble the top end and take a look.

FWIW, unless you have to split the cases and replace the crankshaft, the KDX is actually very easy to work on, much simpler than a 4 stroke.

 

[like-to-ride]

what is the usual compression what range ... (damn I need a manual) and yes its getting gas .To work on I don't think it would be that bad but will check compression son wasn't cranking on it I think he was in third gear

 

[like-to-ride]

ok just got compression test done its at 75 psi so I think rebuild top end is in order ....question how hard is it too do as it will be my first top end rebuild I am mech inclined

 

[2ktrott]

Not hard if it is just the top end that requires rebuilding. You won't know the damage until you pull the cylinder. Engine can be left in the bike, remove fuel tank, carb, exhaust and then you can pull head and cylinder to inspect damage. Post what you find. Not sure if the 93 is liquid cooled, if so you will need to drain anti-freeze and remove radiator hoses.

 

[like-to-ride]

ya its liquid cooled and it has the kips setup too

 

[EYY]

It's a very easy job to rebuild the top end on these bikes. One thing you need to know is that the kips shaft nut (right hand side of cylinder) is LEFT HAND THREAD. Also support the shaft when undoing this nut with a good pair of pliers. Other than that and torque values for bolts you could get away with doing the top end without a manual.

If the top end has destroyed itself, it's likely that the plating is damaged and will require replating or Sleeving. Costs will vary depending on where you live. For a replate only here in aus, it costs approx $800 so Sleeving may seem like a better option as it is usually cheaper and you'll likely not notice any difference in the way the bike runs if the ports are correctly matched.

If its never had a rebuild since you've owned it, I would not hesitate to pull it all apart and replace all bearings and seals while you're at it.


Let us know how it all goes

 

[like-to-ride]

Well ok took top end off to find out that 2 power valves are screwed and I need to bore cylinder another .50mm which brings it up 67.50mm/1.5mm over stock now I'm in the process of finding that piston and rebuild kit. The bike store can get one for 213 dollars and that's just for piston so I might bore 2mm over stock then it will be a 220 and I can get hold kit for 175 bucks .....so right now that's where I'm at

 

[EYY]

Breaking sub valves is very common, especially if proper maintenance isn't carried out. These valves are still available from Kawasaki too, luckily.

You can't have it bored unless it has already been sleeved (I assume it has already been sleeved). I would put the next size piston in it. By boring out further than you need to, you will be sacrificing the integrity if the sleeve along with any future re bores it may need. You're not likely to notice any extra power from just an extra .5mm

Once you get it back together it will be like a new bike. Working powervalves and a good top end will do wonders for power! If you want more power, consider losing the airbox lid, aftermarket reeds and a pipe to really wake it up if it hasn't had these done already

Good luck!

 

[like-to-ride]

ya air box lid is gone and its got gnarly pipe and exhaust also it has been sleeved ...but when this goes again do you just re sleeve and start over at stock bore ?

 

[like-to-ride]

ya air box lid is gone and its got gnarly pipe and exhaust also it has been sleeved ...but when this goes again do you just re sleeve and start over at stock bore ?

 

[EYY]

ya air box lid is gone and its got gnarly pipe and exhaust also it has been sleeved ...but when this goes again do you just re sleeve and start over at stock bore ?

Yes you can have it resleeved, and if you're keen you can even have it sleeved to accept a larger piston to push it out to 240cc. I've heard that you may lose the function of the powervalves if you decide to do this though, but some people say that you don't.

Resleeving is a relatively expensive process compared to boring, so I would still definitely bore it out to the next available size of piston.

Also, have you checked the condition of the bottom end?

 

[like-to-ride]

well haven't posted in awhile so the bike is just about back to together my question is how many hrs to put topend back together (just top end) and kips

 

[EYY]

While you have the barrel in your hand, put all of the power valve components in place and take a while to see how it all works. That way you won't be trying to work it out when it's on the bike which might be a pain. Essentially, with the actuator rod all the way in, all valves should be closed, and with it out they should all be open.

How long it takes depends on how competent you are, essentially.

 

[like-to-ride]

well took it to a shop to install jug and kips that they took apart already they said 1-2 hrs and when they were done with it it came out to 3 hrs they didn't install carb or nothing just new topend and the kips ...... I think they are trying to screw me I would have done it myself but I had no time nor the torque specs for the head or torque wrench so I thought that I would ask here cause people do this al the time and im new to 2 strokes

 

[jaguar]

I would keep on boring it till you run out of piston sizes, then resleeve it.
Too bad you don't have the original nikasil plating which lasts forever till you gouge it.