Way back when we use balance the rotating assembly on big twins, take most of the shake out of them. But they would lose a tad of hp after the balance. Now you just let them shake and add a fluid balancer if you want to take some bang out it. You really don't feel a big twin shake under power, just at idle. My 1000cc 4cyl is 180 fire, so it swings 1&3, 2&4 to TDC at the same time. Less issue and more power then smooth 90* fire at 10,200 rpm. Just sucks to pull it over by hand when it's freezing outside.
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who is making the fluid dampers? I thought I remember them being made a while ago but have not heard of anything lately.
I have a arctic cat 900 based snowmobile motor in a quad that had Hooper's 1100 kit and now a 1000 CPC kit, and they do not shake to bad at idle but smooths out pretty good even revving it to 8500rpms.
The motor is rubber mounted and fuel issues have not been a issue luckily for me even at those rpms.
I also have a M1000 snowmobile and it seams about the same at idle and also smooths out real good over idle. The M1000 are best not to let idle for long periods of time or the rubber mounts get stressed and tear.
My 600cc cr500 based Liger on the other hand has been a vibrating monster and is solid mounted.
The vibrations are bearable for the rider as a drag bike racing in the dunes where you may make a dozen passes but the vibration has caused tuning nightmares. I have consistently battled with foaming the fuel in the bowl.
Problem is the foaming is not consistent, so it can have huge jetting swings from the bowls wanting to overflow to running dry.
going to try a pass through style bowl with foam like the Kart guys use. No float needle is used, just one pump to fill the bowl and another to suck the bowl out at a set bowl height. If this does not work then my only other alternative is to try EFI which eliminates any kind of bowl in the system.