Roketa DB-28 BBB 110cc Chain and Sprocket Questions

Kevbo · 09-04-2009, 09:39 AM

1st gear seems pretty useless on this bike. I heard if you upgrade the sprockets, you can get a little more use out of 1st gear and possibly more power too? Anyone know if this is a #420 or #428 chain? How about the sprockets - Would I need both front and rear? What teeth count is best to achieve the best performance? Any help on this would be great!
Thanks!

katoranger · 09-04-2009, 12:15 PM

I think that alot of the pit bikes came with a 420 chain. What sprockets do you currently have? # of teeth.

If first is too low add a couple teeth to the front sprocket. Much easier to change and you will probably get what you are looking for.

Kevbo · 09-04-2009, 12:21 PM

Thanks - Do I need to swap out the rear or just the front?

katoranger · 09-04-2009, 04:05 PM

You can change just the front.

Weldangrind · 09-04-2009, 10:34 PM

Our 125 pit bike (a Gio) had a 428 chain. you could likely take the existing front sprocket into a bike shop and ask them to wrap some chain around it to be sure.

Check out this gear ratio chart from JT: http://www.jtsprockets.com/fileadmin...tgearratio.pdf

Let's say you have a 14 tooth front sprocket and a 36 tooth rear; that equates to a 2.57 ratio (which is waaay too high, except for land speed records). Switching to a 12 tooth in the front would result in a flat 3.00 (much better).

Don't go any smaller than 12 teeth on the front sprocket, because it becomes too small of a radius for a chain to articulate around at high speed.

09-04-2009, 09:39 AM	#1
Kevbo Join Date: Sep 2009 Posts: 14	Roketa DB-28 BBB 110cc Chain and Sprocket Questions 1st gear seems pretty useless on this bike. I heard if you upgrade the sprockets, you can get a little more use out of 1st gear and possibly more power too? Anyone know if this is a #420 or #428 chain? How about the sprockets - Would I need both front and rear? What teeth count is best to achieve the best performance? Any help on this would be great! Thanks!
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09-04-2009, 12:15 PM	#2
katoranger Join Date: May 2007 Location: Altamont, Kansas Posts: 15,103	I think that alot of the pit bikes came with a 420 chain. What sprockets do you currently have? # of teeth. If first is too low add a couple teeth to the front sprocket. Much easier to change and you will probably get what you are looking for. __________________ You meet the nicest people on a Honda Clone.
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09-04-2009, 10:34 PM	#5
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	Our 125 pit bike (a Gio) had a 428 chain. you could likely take the existing front sprocket into a bike shop and ask them to wrap some chain around it to be sure. Check out this gear ratio chart from JT: http://www.jtsprockets.com/fileadmin...tgearratio.pdf Let's say you have a 14 tooth front sprocket and a 36 tooth rear; that equates to a 2.57 ratio (which is waaay too high, except for land speed records). Switching to a 12 tooth in the front would result in a flat 3.00 (much better). Don't go any smaller than 12 teeth on the front sprocket, because it becomes too small of a radius for a chain to articulate around at high speed. __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
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09-04-2009, 12:21 PM	#3
Kevbo Join Date: Sep 2009 Posts: 14	Thanks - Do I need to swap out the rear or just the front?
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09-04-2009, 04:05 PM	#4
katoranger Join Date: May 2007 Location: Altamont, Kansas Posts: 15,103	You can change just the front. __________________ You meet the nicest people on a Honda Clone.
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