Has anyone put the 500 top end kit on there 2014 420 How was the power...


Has anyone put the 500 top end kit on there 2014 420? How was the power increase?

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  • The only thing difference between the foreman 500 and the 420 is the jug and the throttle body the bottom in the jet everything is the same

  • There's a few more different parts between the machines. The output gears for one are different. The 500 has just a touch lower output gear ratio compared to the 420. A lot of the parts are the same though where it counts.

  • Are the gears really different Roy I did the SRA gears in my IRS but won't a little more are you talking about the gears in the back of the motor secondary gears?

  • Yes and yes. The secondary gears on the 500 are a 16/30 tooth count and on the 420 they are a 22/40 tooth count. When you do the math they are close but the 500 is a touch lower geared. Not really enough to worry about but there are some differences.

  • Thanks man

  • Clutches are the same tho right

  • The change clutch is the same, the centrifugal is different. Your AT is different from my manual shift though (unless your like me and have both).

  • I have a AT its a 2013 IRS but my centrifugal clutch is slipping

  • I haven't had a chance to compare things between the AT and the manual models. I would guess the 500 centrifugal would work on the AT model but that is just a guess. The 500 uses a 6 weight clutch system vs the 420's 4 weight system. I don't have an answer there and would hate for someone to waste money on something I said if it didn't work. I would have to do some looking through the service manuals to see if they give enough spec to compare stuff.

  • Thanks I'll have to ask my mechanic