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Hey Guys, Mollybones here in Maine. After well over 15,000 miles of good times and heavy luggage, my dear friend, The Ratty Pidgeon, is sucking air and it also sounds like his inner sprocket is worn out. Going to replace the engine before our next big adventure together ( The Continental Divide Trail ). Is it possible to put a 250 engine on a TW? Anyone done it before? Thanks!
Love, Bones
 

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Ronnydog, TW-Brian, macbig2k1 are just a few of the guys who know how to build up your TW engine. You could PM them or look for further info here on what they did.
 

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There are 2 schools on this. You can build up your existing engine to get it up to 250 CC s or you can buy a 250 from an XT and go for that. Either of these options do take a lot of intricate engine work and a good machine shop to get it done. The 250 XT engine has to have the output shaft extended and a carrier bearing added so the sprockets align. Not an easy or inexpensive task! The TW engine has to have a lot of machining of the cylinder around the base to accept the larger piston and clear the top of the case. Also a big job.

Not saying these upgrades can't be done because we do have proof right here but there are those like me that would probably tel you to go buy an XT 250 and about all you will lose is the fat tires. You will gain power, 6 speed transmission and much improved suspension. I sure love the threads about these technical upgrades but I have to remember most of the guys who tackle such endeavors either are machinists or have one close by willing to work with them. By the time you are all done and ready for the adventures I will bet you spent more money than just buying a bigger bike would cost. Just My Opinion.

GaryL
 

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I was going to go the XT225 crank route but I decide that what I want more than just a few more horses is the six gears. I'm looking for an XT225 donor and then I think I'll upgrade to a 10.5:1 piston. There is a fellow here that does the mods to a TW tail shaft and that coupled with the TW right shaft bearing is pretty much plug and play. (Circle F Machine) This will give near 20 horses and six speeds with a lower first and a sixth that's taller than the TW's 5th to boot.
 

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You can spend a bunch of money and time getting more ponies out of a $2000 TW and you still have a $2000 TW that is under powered and vibrates a lot.
 

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It's not about the money. I have bigger bikes. Big Red Pigs (BRPs). ....but that's their problem, they're too damn big.

It's got more to do with what I want. I like this little TW. Handles a lot like a trials bike but has reliability and carrying capacity. Just wish it didn't leave my arse and gnyokies numb when doing over 50 mph down the highway.
 

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I haven't heard of that but I haven't been here for very long. The two main options, AFAIK, are to increase the displacement of the TW200 engine or go to the XT/TTR 225 engine. The XTs and some TTRs come with a wide ratio 6 speed which I think is the main short coming of the TW200. More power from the TW200 would still not get you much more in top speed although you would have increased acceleration, if that's what you're after. You would still be winding out at sixty mph. It will require sprocket gearing changes to gain anything in top speed and will sacrifice low speed first for tight trail riding. With the XT/TTR wide ratio six speed you can still boost the ponies with more displacement but you will still have a first gear that's lower than the stock TW200 first and a taller sixth that will make cruising at sixty more bearable. You also get a six disk clutch.
 

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Don't do it!!!
I can only assume this tongue in cheek....

The 6 speed is a really nice upgrade. Upping to the 225 is an improvement, but barely....The combination of the two is worth the effort....But IMO the 6 speed alone is worth all the work involved. I hope to try bumping it up to a 250 eventually, but the ttr 225 donor motors I used were barely broke in....I saw no reason to even install new rings. If the topends had more hours on them would have done 250s for sure, maybe after a few thousand miles I will go that route.
 

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CB350 twins are not really known for their power to weight ratio. That said it is kind of cool. I think it is pretty much a street bike now.
What I would love to see is Yamaha develop A TW400 big brother to our 200, using the new SR400 fuel injected, Kick start motor.
I do wonder what kind of stability issues you would start to see with our low pressure tires at higher speeds that would make possible.
 

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i would second that opinion on the 6 speed conversion. I had the opportunity the other day to swap from my 225 6speed to a friends stocker and back. The power is noticeable, but I think the low end has more to do with the high comp piston rather than displacement. 6 speed is another story and I think well worth it. I think all gears are better off, but I dont miss the 4th to 5th drop in the least. I also really like the 15t front in combo with the 6 speed. It makes 1st about the same and 6th a little taller.
 
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