quick tip for everyone

[bryanwheat]

So i just got my 6 bolt swap done, and i am having some negative results. When i went to built my 6 bolt, i bought a suposid balanced crank that i paid like 250.00 for, i got it and it had some holes drilles in the weights so it was apparent that it had been balanced. I used 6 bolt rods and new 2g pistons in the motor, the piston and rod assemblies are balanced within .5 a gram of eachother, well after i got it together and broke it in, i noticed some vobration after 3k rpm's, the motor has a new balancer, and i had the flywheel resurfaced and made sure that it was in balance. That Leads me to believe that the crank was balanced incorrectly because i have built numerous motors with stock untouched cranks, and multiple different piston rod combinations, but never got any kind of vibration like this before. So If anyone buys a (pre-balanced) crankshaft from anyone, make sure that you have your local machine shop that has balancing capabilities check the thing out, and make sure that it is done right, i made the mistake, and now i am going to be paying by buying another crank, and having it balanced. Don't make the same mistake that i did, it is easy to do, especially when there appears to be done what is supposed to be done.

 

[GTM]

So i just got my 6 bolt swap done, and i am having some negative results. When i went to built my 6 bolt, i bought a suposid balanced crank that i paid like 250.00 for, i got it and it had some holes drilles in the weights so it was apparent that it had been balanced.
...

Was this a new crank? Any chance it was bent? Have you done a compression check. Have you inspected the crank pulley for trueness?

Cheers,
GTM