JMS racing engines give you the confidence to know that you have the power to get you to the front and keep you there and the reliability to finish the race.

Engine packages include cylinder porting head modifications, case modifications, crankshaft truing, and transmission micro finish

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YZ134 YZ150
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If you're racing schoolboy 2 or the women's class and want to ride a two-stroke. These are the engines for you.
The YZ 134 engine package is a drop in kit with no case modifications needed.
The YZ 150 steps the engine up a whole new level. Increasing the engine stroke to bring it to and acceptable bore stroke ratio, the engine produces power completely through the power band without sacrificing upper, end RPM. This engine builds huge horsepower and rocket fast.