TW 200 Top end

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Offline Benton

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TW 200 Top end
« on: November 11, 2018, 01:24:29 PM »
I have a 1994 TW 200 that I got a while back  that was not running.  I was able to get it running and even drove it back and forth to work for awhile.  My kids and wife enjoy riding it as the bike is very easy to learn how to ride on.  But the engine has always had a noise.  Well, the noise finally got bad enough that I took the engine off the bike and pulled the top end off. The piston appears to have been slapping around the cylinder. I am starting to look for parts and options on what actions to take.    The factory piston is just under 67 mm and I am finding very few options for a new cylinder.  I can find a 70mm Chinese brand aftermarket piston but not much else.  Also I will have to have the cylinder bored out.  Would appreciate any advice of information about possible options that I have.  I have added a couple of pics to show the condition of the piston and cylinder.

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Offline will_kc

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Re: TW 200 Top end
« Reply #1 on: November 13, 2018, 04:37:56 AM »
Benton,
First guess is the wrist pin failed on the cylinder.  What do the cylinder and piston rod look like ?  Are they gouged up
 where the wrist pin goes through?

Saw this on flea bay...

https://www.ebay.com/itm/1994-YAMAHA-TW200-TRAILWAY-CYLINDER-AND-PISTON-/332576492756

Interesting thread here with a few cross references for parts.

https://advrider.com/f/threads/the-yamaha-tw200-thread.422523/page-256

Good luck!
« Last Edit: November 13, 2018, 04:41:29 AM by will_kc »
30K and it's still going strong.

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Offline Benton

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Re: TW 200 Top end
« Reply #2 on: November 13, 2018, 09:31:17 PM »
The piston and the cylinder are rough,  gouged up on the pistons and worn on opposing sides on the cylinder.  (I posted pics of the cylinder and the piston but I am not sure if others can see them).  The rod and wrist pin appear to be fine.  I might contact the seller on ebay and see if they can give me better pictures and information about the condition.
Thanks

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Offline Benton

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Re: TW 200 Top end
« Reply #3 on: December 30, 2018, 05:36:09 PM »
I had a local machine shop bore and hone out the cylinder.  I ordered a new piston, rings, gaskets and many other OEM parts.  I had some time off over Christmas so I put the bike back together again.  It sounds so much better,and is much snappier, I have been taking my time breaking the motor in and my kids are excited to start riding the bike again.  Only time will tell how well I did but so far it has been a success and I will be riding it to work when the weather lines out.