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Discussion Starter #1
Hi, im Leigh and im from Dudley (west Midlands) in the UK, i have been big into bikes all my life, passed my test at the age of 19 where i sold my tw125 and moved up to the bigger bikes, i built a streetfigher/road legal drag bike and have had lots of fun doing it, but with the way things are atm, no job, not much money to get out and use my 1216cc bike because its 2 costly to run/fix, ive decided to take a step back and im thinking about getting another tw 125.

I loved my TW when i owned it and regretted selling it since, but i rode my brother-in-laws 125 supermoto yestoday and had such a buzz off it!! so its made me decide, i want a tw but i dont think a 125cc bike with have enough power for me, (overtaking on country roads 60-70mph), ide love a tw200 or 225 but they never released them in the uk


So what im asking is if i buy a tw 125 what can i use to make it a bigger cc so its got that little bit extra umph, i still want the bike to be reliable as i want to use it a lot, been looking around and seen things about using parts off the TTR 225, but not 100% sure what i need or what fits.



Cheers, Leigh
 

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Not to difficult to build a 225 of your 125. Several on your side of the pond have done just that. I'll defer to them for details.
 

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any idea where i can find this information?


You'll need the crank, rod, cylinder and piston from an XT225 or TTR225. The case mouth needs to be enlarged to accept the larger cylinder and the 225 parts installed into the 125 cases.



There are probably a few minor details specifically pertinent to the 125 swap, but that's it in a nutshell.
 

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Cut and pasted from my earlier post:



Yes it can be done, here's a brief summary: Buy a 200cc crankshaft and balancer, piston, cylinder, cylinder head. Strip everything out of your 125 crank cases, bolt them back together empty, bore out the opening to accept the bigger cylinder. Reassemble with the 200 components and rejet your carb.

The bike will be very low geared with the 125 primary reduction and 125 clutch basket, so ideally you want the 200 primary and clutch basket but that's not essential.

You can substitute 200 for 225 Serow, TTR etc if you want to go to 225.



Or alternatively put the TW gearbox components and side cover into a Xt225 Serow engine



I have done all the above and it's worth it to me because I like messing with engines and bought the parts one by one when they became available on ebay for a cheap price.



I hope that helps.



Even at 225cc you won't be overtaking much on UK main roads but much more torque.
 

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Discussion Starter #6
Fantastic!! cheers for the replys, i love messing with engines too, last engine i built was my bandit 1200 motor, but thats got 81mm wiesco pistons flowed head and cams, built it from the crank up a few times now but it gets expensive with 4 of everything lol so doing a single cylnder should be relativly easy compared 2 what im used 2. i will collect the parts over a period of time and start playing then
its the torque im aiming for more than hp.



Cheers, Leigh
 

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Hi Leigh,



if you don't want to spent your time into the engine, I can build a complete 245ccm engine for you.



And you don't need the outer clutch basket from the 200ccm engines, because just the primary transmission is different. You only need the pressureplate from the TW125 type 2 (DE05) -> same like TW200/225 (5 clutch disk's).



Regards, Sebastian
 

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The 200 primary reduction is 73/22 the 125 primary reduction is 74/20 so if you change only the primary to a 22 and leave the 125 clutch basket with 74 teeth they won't mesh properly.
 

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The 200 primary reduction is 73/22 the 125 primary reduction is 74/20 so if you change only the primary to a 22 and leave the 125 clutch basket with 74 teeth they won't mesh properly.
You don't need to change from 20 (125) to 22 (200).

The 125 sprocket fits on the 200 and 225 crankshafts.
 

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You don't need to change from 20 (125) to 22 (200).

The 125 sprocket fits on the 200 and 225 crankshafts.


I know that but if you want to raise the primary gearing you need the primary gear and matching clutch basket.

I also said this is not essential but without it your 200/225 will be very low geared.
 

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Oh, sorry, I've missunderstood it.

125 - 73/22 - 3,318

200 - 74/20 - 3,700

Difference: +11,5%



@ fish1216

So, if you want more torque, than you can keep the org. primary transmission.

And if you want more speed, change to the 200/225 primary transmisson.
 

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Discussion Starter #12
Super, at least if i get a whole engine from a ttr/xt 225 i can have a play and see what suits me best
does any1 else have bikes that are total opposite to the tw? just curious as im going from a 1216cc to a 125/225cc but still get the same kick out of both!
 
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