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Hubs, Gearboxes, Sprockets and Chains Can't find 'em, grind em - hubs and transmissions, problems and modifications to make you run smooth and trouble free

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  #41  
Old 02-15-2017, 01:50 AM
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Tyler6357 Tyler6357 is online now
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Default Re: Best rear sprocket size

I agree with others, 36 tooth minimum with a stock China girl motor and stock pipe and even that will be kinda sluggish on the low end. Get an expansion pipe, high compression head, port the top end. Make sure you have brakes and a frame that can handle extra speed. Also, you might consider a sprocket adapter if you are using the stock rag joint for the rear sprocket, if you put too much torque on bicycle spokes they will bend or break.

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  #42  
Old 02-15-2017, 02:11 PM
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sbest sbest is offline
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Default Re: Best rear sprocket size

The stock 2015 Grubee 66cc seemed to be happy up to 8000rpm, whereas the 2012 Grubee 48cc doesn't even live reving that high. I have a black no-name 66cc China Girl that seemed to only do about 6000-7000. All of this was easy to alter with some porting or a cylinder swap. Balance was another issue, with them getting better high speed balance as they got newer.

So far I am running a 44t on my 66cc and very happy with the balance of speed with quick acceleration, hillclimbing and being able to crawl around on sandy and muddy trails.

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That's a mighty noisy bike you got there, it must haul a lot of ass?
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  #43  
Old 02-15-2017, 04:50 PM
clay830 clay830 is offline
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Default Re: Best rear sprocket size

Quote:
Originally Posted by TheNecromancer13 View Post
Not if you want to have even the slightest bit of fun riding it. Trust us, taking a half mile to go from 0-30 is not fun, and neither is having to pedal assist on flat ground just cause the wind is blowing in your face a bit. If you want more power, either modify the engine, or get a bigger engine.
what size do you think I should get
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  #44  
Old 02-15-2017, 05:32 PM
TheNecromancer13 TheNecromancer13 is offline
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Default Re: Best rear sprocket size

I've said about 4 times now, as have others, a 36t at minimum.
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  #45  
Old 02-15-2017, 05:50 PM
clay830 clay830 is offline
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Default Re: Best rear sprocket size

k thats what ill get
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  #46  
Old 02-15-2017, 06:50 PM
clay830 clay830 is offline
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Default Re: Best rear sprocket size

another problem I'm having is with my chain. I tried shortening it 1 link because it was to long and the top half of the chain (going into the engine) was sagging and rubbing the bottom half. I shortened it and now the chain is to short and the master link won't reach both ends of the chain. What should I do? Add a half link/offset link?

Last edited by clay830; 02-15-2017 at 06:54 PM.
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  #47  
Old 02-19-2017, 03:31 AM
xXNightRiderXx xXNightRiderXx is offline
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Default Re: Best rear sprocket size

My bike is a 700x32c road bike with drop bars. I have a 66cc china girl and a 44t sprocket, and I get to 32mph risking ring flutter. Tire size definitely matters, so do other drive train upgrades. I'm getting a jackshaft to allow for speeds of possibly 55mph. My next build will be a 212 predator Cruiser with a backrest and extra long custom fenders attached to the frame at multiple points. It will also have a long shot muffler and the drive shaft will be lengthened to the native drive side. The chains will be 415h half links. There will also be two auxiliary fuel tanks. This bike should be able to drive at freeway speeds in relative comfort. Clay, if you have the tensioner installed, try lowering it, then try connecting the master link. If that doesn't work, try taking off the tensioner. If that still doesn't work, then you need a half link.

Last edited by xXNightRiderXx; 02-19-2017 at 03:36 AM.
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  #48  
Old 02-19-2017, 11:39 AM
clay830 clay830 is offline
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Default Re: Best rear sprocket size

Quote:
Originally Posted by xXNightRiderXx View Post
My bike is a 700x32c road bike with drop bars. I have a 66cc china girl and a 44t sprocket, and I get to 32mph risking ring flutter. Tire size definitely matters, so do other drive train upgrades. I'm getting a jackshaft to allow for speeds of possibly 55mph. My next build will be a 212 predator Cruiser with a backrest and extra long custom fenders attached to the frame at multiple points. It will also have a long shot muffler and the drive shaft will be lengthened to the native drive side. The chains will be 415h half links. There will also be two auxiliary fuel tanks. This bike should be able to drive at freeway speeds in relative comfort. Clay, if you have the tensioner installed, try lowering it, then try connecting the master link. If that doesn't work, try taking off the tensioner. If that still doesn't work, then you need a half link.
Neither of those work. I have to get an offset link. I am debating on whether I should get the half link or just buy the sprocket and wait to install it and shorten the chain to match the sprocket. Anyway what size sprocket do you think I should get with a stock chinaman? 36 or 32?

And if I replace the carb and get an NT speed carb then what size sprocket should I get? Or does it not make a difference?
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  #49  
Old 02-19-2017, 01:14 PM
clay830 clay830 is offline
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Default Re: Best rear sprocket size

Do you guys think my bike would be able to pull a 32t or not? I really want the 32t but think I would be risking to much. The reason I want the tooth count to be as low as possible is so that I can be able to cruise at higher speeds than 25mph. With my stock china I can hit tops 30mph. If I put on a 32t, I could theoretically hit 40 mph at top rpm. Say my top rpm is 7000 and with a 32t at 4000-5000 rpm I could cruise at 33-35 or so but with a 36 I would be cruising at 29-30 or so with a top speed of 36mph. I want to be able to also ride at the highest speed possible on those back roads.

Last edited by clay830; 02-19-2017 at 01:23 PM.
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  #50  
Old 02-19-2017, 02:35 PM
xXNightRiderXx xXNightRiderXx is offline
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Default Re: Best rear sprocket size

Let's just say that my stock engine has a bit of trouble starting from a stop with the 44t. I doubt yours would be able to do much of anything fun with a 32t. I wouldn't go lower than 38t, but if you are looking for speed above everything else, then you do not go lower than a 36 for a 66cc china girl, as several others have said. If you have a welder or know someone who does, get a go kart jackshaft. That will completely eliminate the need for a rear sprocket, but you'd need to take the pedals off. That is not to say you absolutely need a pull starter, but you would have to put on the left side pedal every time you want to start it. The jackshaft will allow you to get to the highest speeds possible, while being able to climb mountains.

Last edited by xXNightRiderXx; 02-19-2017 at 02:40 PM.
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