seized KDX 200

[daggles]

Hey all. i'v just gotten into the whole dirt bike thing, and brought myself a KDX 200. 84 i think it was.
ridden for a few days. got the basic idea (im still pretty timid but getting there)
jumped on it the other day, warmed it up, took off no problem. i keep the bike at my mates place out bush
so we just use the road to get to wear we ride, no issues. just before we get to the place we normally ride,
the bike seized completely! i was moving at ful clip when it happened, locked the back wheel and put me into a skid.
i pulled the clutch and rolled to a stop (still on bitumen) and we checked it over. crank will not budge, when the clutch is out,
wheel will not turn.
the guy i brought it off has no idea bout bikes, and i dont know shit bout 2 strokes.
i havn't taken it to a shop, too close to chrissy and prob gonna charge an arm and a leg even if its something simple.
anyone had any experience with this sort of problem?
any tips/help would be much appreciated!!!!

[shan]

Love the smokers , love the hart sizsures that come with them.Re-bore time, head off- Gasket yep X 1, barrel off, new sleeve ? piston ? rings for shure.Get used to it, its worth it.Not hard to do, when you start sergery, use some paper or a rag arround the conrod to prevent any circlip or whatnot dropping in places like the case.Most of the time its just a ring picked up , in my expiriance at least.

[daggles]

cheers mate. gonna open her up in a few weeks. any idea on a price i could be paying for parts?

[shan]

Sorry bud, be lying if I did, its been years since I have rebuilt a motor let alone a stroker.
I have gotten away with just rings and a hone,
It really depends on whats picked up, normaly its just a ring a stated.

Good luck
The KDX 200 is a good toy

[michael]

buy my rego'd '91 model..... ummm just pull it apart and see whats wrong simplest way. for cylinder repairs use electrosil over east, had good exprience when myne did a big end and lunched the entire motor.(even sorted a big bore kit)

michael.

[Crobbo]

cheers mate. gonna open her up in a few weeks. any idea on a price i could be paying for parts?

Just had a jug light honed with new piston and rings for 350, by Ray Easson in bayswater.

Just a rough idea.

[smeghead]

PM Skut (View Profile: Skut - Perth Street Bikes), he just had ray Eason do a rebore for him & will prob be able to give ya a good heads up on the cost.

[orangeflash]

buy my rego'd '91 model..... michael.

yeah how much photos?

[michael]

orange, will pm.

[Marty MOOSE]

A bike of that age bare min would be feel the mains measure the big end and replace the main seals. Then check the carb and for other air leaks.

MM

[PaulMac]

I wouldn't be throwing any new parts into it without working out what is wrong with the jetting. Two strokes don't seize for no reason. Did it seize under full throttle or full clip as you put it? Main jet too small. Did it seize when you backed off from full throttle? Pilot jet too small. Yep, check for air leaks around the reed valve and behind the ignition rotor as you'll never get the jetting right with crankcase air leaks. Run a top quality 2 stroke oil in it at 40:1 and jet it to suit. At least do a plug chop to check the main jet. Remember, you might have been doing 100kph on the road but most likely at that 100kph, you were only on a 1/8 throttle which is the upper part of the pilot jet area. Richen the needle clip as well. Air cooled 2 strokes need richer mixtures as well to help keep them cool.

If you rebuild it without working out why it seized, you are wasting your money as it will likely seize again.

My CR125 never seized or fouled a plug in over 2 years of riding and the pistons hardly wore out and the throttle response was excellent as I took the time to jet it to suit the conditions.

[daggles]

it would have been at least 90, and still under full throttle.
When the guy i brought it off, first brought it, he had all the bearings replaced and a bit of engine work done
(had it honed i think) and just a few other parts replaced. he didn't ride it much after that. then parked it up in his shed for bout 18 months.
when i brought it, fresh fuel/oil mix. new trans oil and checked it all over, worked a charm.
was a real bitch to start that first day thou.a
rode it for bout 3 full days and on the 4th she seized.
she's always been ran rich, with the oil at 25:1
i've never worked on two strokes of this size (only on whipper snippers etc)
gonna try pull the head off bout wednesday.

[PaulMac]

If it was under full throttle for any length of time when it seized, then the main jet is too small. Usually, the bike will go full throttle for around 15 seconds before the lack of lubrication and excessive heat around the exhaust port (caused by too small a main jet) causes metal to metal contact and engine seizure.
Also, you can run your 2 strokes at 10:1 and still seize them. The more oil you put in a 2 stroke mix means less fuel to burn which means you are effectively leaning out the jetting. Lean mixtures make 2 strokes run hot which breaks down the oil film.
Personally, I would recommend a good quality fully synthetic 2 stroke oil (Motul 800 is my choice for over 15 years) at around 35 or 40:1. I would pull out the carby jets and see what size main jet is in it and then go up about 2-3 sizes. Buy a couple of jets either side of your initial selection and then find a long quiet dirt road. Warm up and run in the engine, Put in a brand new spark plug and then run the engine up through the gears under full throttle and run it in top gear full throttle for only about 5-10 seconds. Lock the back wheel with the brake while still under full throttle and bring the bike to a halt with the engine stalled. Pulll the plug; you are looking for a dry plug with light tan colouring down inside the white electrode part of the plug. Wet and black means too rich, white as a ghost means you are gonna seize it again and cost you lots more money. If it is white, go up on the main until you start to get a light brown electrode. Once you get this, you can extend the full throttle time out to 20-30 seconds to make sure you have the bike rich enough. You can jet a 2 stroke (or any bike) to run full throttle all day like a Finke bike; you just need to get the main jet right.
Just remember, dirty air filters and engine air leaks will affect your jetting as well as summer and winter. Bikes will run lean in winter with the colder more dense air. Just make sure you run the plug on the slightly dark brown side on an air cooled engine and you should be good. Once you take the time to set your jetting, it should be ok and not vary too much. Just always carry a spare spark plug with you but my CR125 never needed a spark plug in over 2 years because the jetting was spot on.
If you need any more info, just google "plug chop". There's heaps of info on the net.

[dazza1968]

So is the kdx all fixed yet ? Regards dazza