KMX 200 major engine problem - help appreciated

[chris1x]

Hi

1989 KMX 200, ran fine then the other day after a 20minute 60mph run, a few miles off the m-way i felt a rattle/vibration through the handlebars then i could hear a rattle/clang from the engine, seemed to be from the bottom of the engine.

Limped slowly home. Smoking now too which is getting progressively worse, also starting to cut out after being started.

It will start/run and seems to have plenty of power but i don't want to seize it/bolox it up completely.

It's done 15k, i have no record of previous work done to it. It's ok in every other way. Tax n test till June 2011.

It's my only form of transport and it's really fooked me up as i start a degree in liverpool wednesday (would have been ideal as free tunnel, easy parking etc).

1 local bike shop said they 'dont work on 2 strokes', another said they'd struggle to get parts. Did a quick google for piston/rings and found suppliers straight away.

I would like an opinion on what it is please? Would anyone like to take it on as a job or recommend me a mechanic near to Chester?

Thanks

Chris

[stevo as b4]

They did have a reputation for wearing the bottom ends more quickly than the KMX125 having exactly the same bottom end. The main bearings were the common thing that used to wear out within 15-20'000m. The big end could also be worn, but the std 200 is quite low revving compared to a hot 125cc stroker, even so it's all based on 125cc sized bottom end components.

Your bike sounds like it has worn main or big end bearings, seeing as it still starts and as you say has some power. If it's a rumbley vibration through the footpegs and that it never goes away when revved, then id say it's a main bearing issue. If it knocks and sounds a bit clattery then it's most probably the big end bearing.
Either way it's a full engine strip down job to replace, and while your at it all the crank case seals and gaskets should be changed for new, and a new piston and rings fitted, as it's not worth running a worn piston and rings in a Nikasil bore due to the cost of repair if it lets go.

My 200 packed up when a peice of piston crown broke off and snapped the rings which then fell down into the crankcases. The bits of mashed piston went down the exhaust and i found them when i removed the expansion chamber and shook it upside down.

I can't be too specific about what parts are not available for the KMX200 engine now, but Kawasaki bikes from the late 80's-early 90's are notoriously harder to get new spares for than the other jap bikes, due to Kawasaki not supplying new spares for very long 15yrs? The last i heard was that new gearbox components and particualary the 2nd gear set was NLA new.

Pistons, rings, gaskets and bearings will always be available however, and decent pattern parts are just as good in most cases as Kwak Genuine parts.

[Ariel Badger]

Big End
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[chris1x]

^ thx for taking the time to reply.

i've noticed the engine sounds normal for about 10 secs when started from cold then gets noisy. you can feel the vibration through the footpegs and the bars, the noise is like a clatter/rattly with a bit of rumble. it did seem to still have plenty of poke but im not going to run it again now.

the work required is way beyond me, no local garage is interested, so im putting it up for sale if anyone's interested, will probably go on ebay. got to be worth £295 (no offers on that) to somebody... these seem to go for £750 in good order. note the ignition/fuel cap locks are broke as i lost the keys, any key fit's the bike. apart from that (and the engine problem) the bike had no problems and was in daily use. it was a fun light bike, good mpg etc. very gutted this has happened to be honest.

thanks again.

[chris1x]

[Frost]

I'm no expert but others saying that the bottom ends have a habit of going suggests that its the same bottom end as the 125 thats struggling to last with the additional power going through it.

Differences are likely to be cylinder, head, piston & carbs.

If you get a 125 engine the chances are it will bolt straight into the frame, but you will then need a 125 carb and will be taking a chance on that engine being screwed too.

You have nothing to lose by stripping the engine down and having a look at things. If everything is beyond repair, you will know you need a new engine. If things look repairable then thats your best bet. You can get a 2 stroke bottom end out in about an hour (literally just undo everything that can be undone, it's not rocket science!). Take it to somewhere to get it fixed saving yourself a fortune in labor charges. Whilst it's all apart it would be a good time to change the top end. It might not be needed, but is a good idea if your planning on keeping the bike. Putting it all back together is about a days work for someone inexpirenced. Either do it with the help of a manual, or there are probably a lot of youtube videos about. Manuals and guides for the 125 will be sufficient.

[chris1x]

^ thanks for your input. i've bought another bike now as i needed 1 for today, a boring middleweight but it's far more suited to the 50 mile roundtrip.

can't be bothered with the kmx so it's going on ebay. i really these bikes and would have another similar style of bike (2 stroke mx) but it'd have to be much newer, a bike that mechanics would work on, and have less miles etc.

thanks.

[stevo as b4]

Sorry to hear that! I know you said that it's your main transport but KMX's are fun bikes especially in 200cc form!

I know that 200cc top ends fit onto a 125cc bottom end, and i see no reason why you can't do the reverse although i've never hear of anyone doing it? TBH i know it's and expense, but i think a decent full crank re-build and new main bearings and crank bearing seals would have sorted you out for another 20k! If you change pistons and rings together for new items every 10k, the cylinder bore can last over 40k easy if the engine is running correctly.

You might be able to find a secondhand 125 or 200 engine, but 200's are comparitively rare, and there are some internal engine/gearbox parts that a NLA new, so for finding an engine that has a fair chance of being a decent running unit, a 125 is possibly better. I've never brought a secondhand 2stroke engine and just thrown it into a bike, unless i knew where it had come from and it's mileage and history etc. On a 4stroke i've chanced my luck on a used motor without too much of a problem though.

It would be nice if you can keep your KMX and get it sorted and back on the road again, as they are getting a bit rare now and are cool bikes! As you say a decent condition running bike with an mot will fetch £600-850 these days, but they will probably go up a bit more over the next few years.

Im not really looking for another KMX at the moment, although when mine is done, i'll have enough bits except for a frame and forks to build a full rolling chassis and i've got lots of old bodywork, a tank, seat, wheels and a spare carb etc. If you really do want to get rid of it then let me know where your located and how much you want for it ok mate.

[andy_g2k7]

im not far from you ( new brighton ) and there are about ten garages around here that would be happy to look. mike hose is on wheatland lane he deals in motocross and mainly 2 strokes such as yours maybe worth a visit and a chat
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