hot rods stroker crank issues

[bazuki54]

well its an issue to me. it might be normal. i have a 2008 yzf 450 and i put new crank bearings along with the hot rods stroker crank and now it vibrates. i have intalled crankshafts before and i always had to press the crank into the bearing on the one side. but not on this hot rods crank it slid right in. so now it vibrates when its reved. is it normal? should i be concered? i hope its normal and all stroker cranks vibrate. i appreciate any feedback.

[grayracer513]

The crank wasn't correctly rebalanced for the stroke, or possibly for the piston you chose. The crankshafts are balanced to a percentage of the reciprocating mass (piston assembly and the upper half of the rod), and then the counter balancer is weighted to offset that.

It isn't unusual to have the engine vibrate more after changing something in this set of parts. If it's bad, it should be corrected.

[bazuki54]

thanks for the respond i just dont know what to do. i put in a stock piston like hot rods said to. the crank was trued it vibrates i think it vibrates because the crank slide right in the bearings without use of a press. should i still ride it? it seems ok when ridden. if i didn't get such a good deal on it i would have got a stock crank.

[spark250]

This has always been a concern of mine with stroker and big bore motors. as gray mentioned the counter balance would have to be modified with either of those changes. If not I would assume there would be vibration issues etc.

Do these kits offer different counter balance weights or is it such a small % that it doesn't really matter?

BTW the crank just sliding in the bearing would worry me. Although if it was an issue I think some scary noise would be present with the vibration.

[sandrappy]

The hot rods cranks are known to not be balanced very well. If you balance the crank to your piston weight it will fix the problem. I have the +3mm crank and had it balanced before installing it, and it runs smoother than the stock motor.

[bazuki54]

how do i balance the crank to the piston weight? its not making any weird sounds. hot rods claims they are balanced and trued.

[grayracer513]

hot rods claims they are balanced and trued.

Interesting claim for you to defend, considering how it shakes.

A machine shop specializing in balancing cranks for small engines will have to do it.

[sandrappy]

I have crankworks balance all of my cranks. Falicon also does very good work and is quicker, but a bit more expensive. They will have to add heavy metal to the crank webs to get into balance and then it will run smooth. Bad thing is you have to tear your motor apart again to get it out.

I have seen guys run with out balancing the cranks and haven't seen them harm the engine. However it is added stress and can add to rider fatigue and arm pump.

I think crankworks chargers $200 plus the cost of heavy metal to tear one down and balance it. You will need to send your complete piston kit in that you will run so they can balance the crank to the weight of it (including pin and rings)

[William1]

I have Falicon do mine. Smoother running s stroker than OEM!