Big bore 2nd gen 125m

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This has been something that I've had on my mind for a few years but things have just recently come together where I could bring them to reality. Long story short I wanted a more powerful engine for my 86 125m but there's no performance parts that I've seen available. So I think I've found a combination of parts that with a little modification will net at least 183cc and more if I go oversize from the current bore. What I've come up with is a crf230 cylinder and head that I've had shortened and 125m cases that are bored to fit the cylinder. With using the crf230 head I'll also be able to use the roller camshaft that at the engine size I'm running will be like having a bigger cam since it's only 183cc. I'm waiting on a piston, cam chain, gaskets and the heavy duty clutch parts I ordered to come in so I can have the cylinder sized properly and get it together. I'm going to upgrade to a 24/26mm flatslide carb and use some type of cheap (for the moment) crf230 exhaust until I work any bugs out and I'll upgrade from there. My goal is for it to appear stock as far as the engine but eventually be over 200cc and be a little lighter than a normal 200.

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[Trike_crazy]

I forgot to add that stock the 1986 125m is 54mm bore with a 54.5mm stroke. I'm increasing the bore to 66mm with the crf230 cylinder and using the next oversize piston from stock which is 66mm.

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[shortline10]

Awesome , hopefully the crankshaft won’t be to far out of balance with the much heavier piston .
Might vibrate some but I’m excited to see how this turns out .
I’ve installed a 200x camshaft in one and it definitely helped , just had to cut the correct length off the end because the 125m motor doesn’t have the pulser up top .

[Trike_crazy]

Picked up some barnett clutch frictions and some heavy duty springs. Frictions are for a 200x but they are the same dimensions and the springs are for a cr80r. Also got the gaskets to put it all together but I'm still waiting on the clutch Steels and the all important piston. I ended up getting a 67mm piston because no one has any wiseco forged pistons in stock smaller than that for a crf230. So I'll be at 192cc with this combination when finished.

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