If a Honda XL 125 or 185 counts as a thumper......

[guest1405]

Can anyone tell me whether I can fit a 185 top end onto 125 crankcases. I have a knackered 125 engine which I want to rebuild and wonder if its possible to build it as a 185? I guess the main question would be if the 185 crank would fit the 125 cases? Thanks, Tony.

[guest564]

It will fit but you'll have to open out the crankcase opening to take the barrel, you may need the 185 gearbox as well, I don't remember the details of that. Of course you can also bore out the 185 barrel to take an XR200 piston.
You can do an awful lot of swapping around on these old engines, In have a TL125 engine converted to 200 and an XL185 converted to 200 with a six-speed box that, I think, came out of a CB125RS - the ratios are the same as the XR200. I used to do loads of work on these but it was all a very long time ago.

[johnr]

im pretty sure the 185 has a different stroke to the 125.

[guest564]

Its a different stroke but it fits in the 125 cases, you do need the 185 barrel because its taller and you will also need the camchain, tensioner and guide.