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Heads and Cylinders All about your porting, compression, rings, cylinder and piston modifications to your bicycles engine

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  #1  
Old 01-28-2016, 03:14 PM
Mouse Mouse is offline
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Default Big jugs

I have a 48cc grubee Skyhawk 2 stroke can I change the jug and piston to a 66/80cc?
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  #2  
Old 01-28-2016, 05:24 PM
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Default Re: Big jugs

Large jugs? Sorry...was expecting to see something different here. lol

Really don't know why you couldn't go with the larger displacement jug. I think the lower ends are basicly the same on most all the china girls and I would assume the cranks the same, but perhaps more research is in order
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Old 01-28-2016, 08:58 PM
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Default Re: Big jugs

The stud spacing is not the same, I don't have the specs but I do know my 48cc's and the one 66cc are different.
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Old 01-28-2016, 09:34 PM
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Default Re: Big jugs

Is there any one who could help me with finding a faster reliable motor ? I'd like to go35-45mph without going wide open on the throttle. And can I modify the existing motor to do that?
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Old 01-28-2016, 10:00 PM
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Default Re: Big jugs

There are a lot of modifications that will increase speed, porting done right is one. Adding a expansion chamber is another, changing rear sprockets from a stock 44t to something with less teeth will increase top speed but cuts hill climbing ability. If you do upgrades do one thing at a time, that way you'll know if what you did helped or hurt performance.
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Old 01-28-2016, 10:32 PM
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Default Re: Big jugs

What about a jackshaft and hooking it into the existing bike gears?
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  #7  
Old 01-29-2016, 06:07 AM
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Default Re: Big jugs

Yes a jackshaft kit will help, here in Georgia a multi-speed moped is not legal so you might want to check your state laws.
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Old 01-30-2016, 03:15 PM
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Default Re: Big jugs

Mouse, getting a bike to do those speeds is not a problem. Doing those speeds safely is the real issue. You are asking for motorcycle performance from a bicycle, so that bike and all of it's components must be up to the task. I'm guessing that about 75% of your budget and efforts should go into building a solid bicycle foundation to bring it up to manufactured moped standards.
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Old 02-04-2016, 04:01 PM
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Default Re: Big jugs

Got a grinding feel in bike when motor is engaged. Bearing? Time to rebuild?
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  #10  
Old 02-04-2016, 11:18 PM
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Default Re: Big jugs

Quote:
Originally Posted by Greg58 View Post
The stud spacing is not the same, I don't have the specs but I do know my 48cc's and the one 66cc are different.
6mm studs at 42mm for the 48cc.
8mm studs at 45mm for the 66cc.

Steve
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