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Old 01-23-2012, 02:18 AM
recon chris's Avatar
recon chris recon chris is offline
Motorized Bicycle Senior Member
Join Date: Apr 2011
Location: pacific grove
Posts: 87
Default Re: Getting all 3 Horse Power out of your GT-5 Sky? (tear down)

Balancing part 2

I finally finished balancing the crank. I thought it would take 30 minutes but it took an hour and a half.

After taking only 6 grams of weight off of both fly weights I went to balance it. It balanced crank pin up without the bob weight (that’s a good sign) then I attached the bob weight and for the most part it was balanced. But trying to be the perfectionist that I am I went "heavy end hunting" for an hour. I must have drilled and weighed that thing 30 times before I felt I got it right. In the last few drill and balance sets I was taking off only tenths of a gram. That is when I had to stop myself and say "that will do pig that will do".

Here are some picks of the crank after I balanced it tonight, you would be amazed at how much material you have to remove to balance this thing. Believe it or not the entire crank assembly is only 22 grams lighter than when I started but dam does it look like allot of material.

Before balancing the fly weights
After balancing

Upgraded the balancing rig to rails instead of setting the crank up on bearings. The bearings have too much resistance for the fine work. However with rails it will drive you crazy because there is so little resistance that you’ll always find a side of your crank that is slightly unbalanced.

Balanced crank on rails.

If you balance your crank on rails make sure the rails are level if there not the rig will give you false readings

Tomorrows agenda involves properly pressing the bearings back into the magneto side of the crank case. And setting the crank in sed bearing. Then ill be attaching the piston and seeing if I need that piston skirt trimmed or not.

Please comment and ask questions I love hearing what you guys have to say.

Last edited by recon chris; 01-26-2012 at 04:42 AM.
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