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mix and match?

1088 Views 7 Replies 5 Participants Last post by  jontow
hey guys, been a lurker for a while, reading lots, great site.

So i recently was picked up a couple TW200's site unseen for a good price thinking i could at least get one to go. first one is the beauty, 2006 with 3000 miles on it, mostly complete minus CDI; second one is the beast 1991, looks a little rough missing carb and CDI. I have no idea of the history of either bike.

I was able to find a CDI on ebay for the 06 so i started with that one. started cleaning it up, and when i changed the oil the filter was full of metallic flakes/sledge, not sure if these bike are prone to that or not, would have thought by 3000 mile the case would be cleaner, so i am assuming something is buggered on the inside. after cleaning out and refilling it i tried the starter and it would just click like a dead battery, but power was getting to the starter. pulled starter a part looked good, put back in and now it will turn weakly a couple times and then click again, and the battery was strong even tried boosting off my truck. bike has spark. finally it does not seem to be getting fuel when trying to start, and the carb is clean, can see light through all the jets. just stumped, so i moved on to the 91.

the starter on the 91 cranks nice and normal, and with the kick start i the motor feels right. but no carb or spark stops me there.

So long story short, can i use the 06 carb on the 91 bike, and any mickey mouse way to bridge the newer cdi to the old bike to test it? or am i better off swapping the 91 motor into the 06, probably have to swap the charging system?? maybe just swap the starter to the 06 and see what happens?

anyways sorry for the novel, just trying to wrap my head around these bikes as they look like a tonne of fun.

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You're correct, except you'll also need the flywheel/rotor from the later motor. Pretty much an afternoon's work.

The only difference remaining is the automatic cam chain tensioner. If you want it can also be transfered over to the early motor while the side cover is off to swap flywheels.

But don't throw the baby out with the bath water just yet. Find out why the late model motor won't turn.

I'll offer two possibilities. To check either on a bike which has been sitting for awhile you should remove the spark plug, put a couple of tablespoons of ATF down the plug hole and let it sit overnight. That will help minimize any scarring of the cylinder if there is any rust haze in the bore:

1. Best case scenario: The starter relay has failed or corroded and is arcing internally. Easy test. With a full charge in the battery, freshly cleand and tightened battery terminals and the bike in neutral just jump the two big wires with a 10 gauge wire, one side of a set of jumper cables or even the points of an old pair of needlenose pliers (Key doesn't need to be "on" for this). If the motor spins replace the relay. But don't replace it with a late model solid state relay. Use either a mechanical one from an early TW or one from a larger bike. Late model TW relays are doodoo.

2. The motor sat for a long time and the rings have siezed to the cylinder. Do the ATF thing, then next day rock the bike forward and backward while in third or fourth gear. Don't force it, just bump it and see if the crank moves. Let it sit, repeat. Sometimes you'll get lucky, but most times you'll still need to do the top end just for peace of mind. You'll need to free it up regardless in order to get it apart once it's out of the frame (It's actually a good idea to follow this procedure on any unknown motor before firing it up).

If it's rust siezed the engine swap is probably your easiest and cheapest alternative. One shortcut is to do the flywheel swap while the both motors are still in their frames with the chains hooked up. Put the tranny in fifth gear to remove, replace and torque down the flywheels. If you don't do this in advance you'll have to wrestle with finding another way of keeping the motors from turning.
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The covers all look the same externally but the castings are different on the inside. The rotors are not interchangable, so they have to follow their respective sidecovers when swapping.

I'd get the later model's starter issue solved and see what you're really dealing with.

You said it sounded "off" when you jumped it. Were you referring to the starter or the engine?
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