View Full Version : What 125's will fit into a rs?

05-15-2004, 03:05 AM
Just wondering if any knows what 125cc engines fit into a rs50. I want a new project and this sounds great.

Micah / AF1 Racing
05-15-2004, 10:38 AM
RM, KX and YZ are the easiest.

05-17-2004, 09:54 AM
I put a 1999 yz 125 cart motor in my 2001 rs 50. The bike runs great. It red lines ar 14,000 because it's a cart motor. It also puts out 40 hp. I only had a couple of problems with the project. The 1st problem I had was the engine was resting on the swing arm and the front of the engine were the power valves are were touching the motor mounts. I had to file down some of the engine and the bike vibrates alot less now. If you are good with metal and know how to fabricate and have a 125cc motor then I say go for it. I was so happy when I first started my bike and it was loud as hell.

05-17-2004, 09:59 AM
When im 17..

Do you think its better to part X a RS50 or stick a 125 lump in it?

05-17-2004, 10:30 AM
Originally posted by Spike
When im 17..

Do you think its better to part X a RS50 or stick a 125 lump in it?

just sell the rs50 and buy a rs125, simple :P

Key Walshe
05-17-2004, 10:33 AM
As you're in the UK p/x or sell the 50 privately and buy yourself a 125 - Rs, Mito, NSR etc. as nobody is in the market for a modded 50 when you can simply buy a 125 which is much better equipped, suspension, brakes, frame & swing arm, tyres/wheels. In the States it's different as 125's aren't legal so that's one of the options they use to replace the 50 motor, but here in the UK it's pointless...