I've seen threads about 212cc predator engines & vibration, just wanting to know about other people's rides & what they find is "normal" with a modded motor. The build is a 212 hemi, billet rod & flywheel, 11:1 Bullfrog piston, Black Mamba cam, mild porting, header & Mikuni VM22-133 carb with GPS intake. Nice combination & it seems to make good power once it's up on the can a little bit.
It runs well & is broken in now, but here's what I've found with this motor setup. This is my first modded motor build, so I don't have anything to compare it to. With the lighter flywheel & different internals, I have a vibration which runs from about 4,000 - 5,200 rpms. It's not really all that bad, but it's nasty until the speed builds up & it climbs out of this rpm range. Mostly it's just annoying, but it's bad enough to cause some discomfort when riding.
I know there's no real way to balance these single cylinder motors, unless it's for a given rpm range, but is this going to be a problem later on if I stay out of the "bad" range & try to run above & below the shakes? It's pretty reliable the way it's running & so far there have been no issues with the build (other than jetting for the first time on a Mikuni, PITA until I figured it out). It does kick once in a while, if I'm not careful with the starting rope & getting on compression correctly when I pull, I wear gloves now just in case.
Anyway, just wondering if anyone else has seen this to be a normal consequence of a build & harmonics at a given rpm range. Thanks.
P.S. Picture of final assembly is with the Chikuni VM22, not the VM22-133 which it's running now & tuned with.
It runs well & is broken in now, but here's what I've found with this motor setup. This is my first modded motor build, so I don't have anything to compare it to. With the lighter flywheel & different internals, I have a vibration which runs from about 4,000 - 5,200 rpms. It's not really all that bad, but it's nasty until the speed builds up & it climbs out of this rpm range. Mostly it's just annoying, but it's bad enough to cause some discomfort when riding.
I know there's no real way to balance these single cylinder motors, unless it's for a given rpm range, but is this going to be a problem later on if I stay out of the "bad" range & try to run above & below the shakes? It's pretty reliable the way it's running & so far there have been no issues with the build (other than jetting for the first time on a Mikuni, PITA until I figured it out). It does kick once in a while, if I'm not careful with the starting rope & getting on compression correctly when I pull, I wear gloves now just in case.
Anyway, just wondering if anyone else has seen this to be a normal consequence of a build & harmonics at a given rpm range. Thanks.
P.S. Picture of final assembly is with the Chikuni VM22, not the VM22-133 which it's running now & tuned with.