100% RPM's grubee skyhawk

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otis

otis

New Member
Mar 7, 2010
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Canada, Kingston,Ont
hey guys, I have the 48cc Grubee skyhawk,old style carb,i honed out and cleaned up all port manifold and exhaust, but didnt actually touch the ports on the cylider itself,this did nothing it still didnt get full rpm's it sounded like it had a govenor still.so i took the cylinder off and matched up all ports best i could ,took a lot of metal off cylinder por,planed head a bit reassembled and instead of topping at 45kmh the rpm's keep revving to 51kmh/31mph {i have GPS} it vibrates a bit and is a bit too high rpm's for cruising but its awsome that thier tere when u need em, i have stock plugs,caps,wires and carb {except i honed it right out} but am looking to change that,I have lots of torque but want more speed without more rpm's so im gonna gear down from my stock44T to one size smaller around33T maybe anyone know the cheapest place to order from and what kind of gains ill get?? and anone know how to get vids from ps3 onto here or youtube? thanxxxx for helpevwryone i love this forum wicked, happy rippin
 
bairdco

bairdco

a guy who makes cool bikes
Aug 18, 2009
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living the dream in southern california
popular belief is for every tooth you drop you gain 1mph. works on paper, more or less.

plugs and wires you can get cheap from a good auto parts place.

manic mechanic sprockets and adapters are the way to go. try him or pirate cycles, they carry them.
 
bairdco

bairdco

a guy who makes cool bikes
Aug 18, 2009
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living the dream in southern california
most popular seems to be the NGK B6HS. i run the B7HS, and a lot of people run the B5HS.

you can't go wrong with NGK.

as for plug wire, i buy 7mm copper core wire by the foot, boots and terminals and make my own. it's really simple.
 
Cabinfever1977

Cabinfever1977

New Member
Mar 23, 2009
2,288
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Upstate,NY
Wow i didnt do anything to my motor and it goes 32mph already.
I thought about getting a smaller sprocket to gain 3mph, but decided not to cause i dont think it would be worth paying $20+ and i dont have to peddal at all now but u might have to if u get a smaller sprocket.
 
bairdco

bairdco

a guy who makes cool bikes
Aug 18, 2009
6,537
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living the dream in southern california
i run a 30t on a 24" bike with a grubee starfire 66cc and it hauls. it also has good torque off the line. part of that is because of the smaller diameter wheels. the other reason is because my motor is the most freakin awesome motor i ever blueprinted...

anyway, despite what Joe's tellin' ya (;)) if you have the chance ($) experiment with different sprocket sizes. plus, it'll keep the forum sponsors in business.
 
Venice Motor Bikes

Venice Motor Bikes

Custom Builder / Dealer/Los Angeles
Mar 20, 2008
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Los Angeles, CA.
Bikeguy Joe said:
I wouldn't go down to a 33T, 40T should be about all your engine can haul.
Click to expand...
bairdco said:
i run a 30t on a 24" bike with a grubee starfire 66cc and it hauls. it also has good torque off the line. part of that is because of the smaller diameter wheels. the other reason is because my motor is the most freakin awesome motor i ever blueprinted...

anyway, despite what Joe's tellin' ya (;)) if you have the chance ($) experiment with different sprocket sizes. plus, it'll keep the forum sponsors in business.
Click to expand...
I concur with Joe; 40T is a good sprocket... Baird's bike is real fast, but he always forgets that not everyone weighs 130lbs like himself. laff
 
flybytaco

flybytaco

Metal Molding Madman
Oct 17, 2009
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seekonk MASS
if you want more rpm's go with a 48t it will rev more and actually make it go faster. annything lower than 44 on a 48cc will dog it down
 
breno

breno

New Member
Aug 19, 2010
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Syd. OZ
i went from the 44 to a 36 and i reckon it made approx 10-12km/hr difference.
you will find that the motor wont 4 stroke as much too coz its under load more often with the 44 tooth and how easy it gets up there I found the motor seemed like it was effortlessly running and causing the 4 stroking effect from bugger all throttle at speed. You will find it will cruise better too without revving its guts out.

IMO 44t is good for hilly short suburban rides and having fun the 36t is good for not quite as hilly long rides where you'd like to keep the revs down.

You should find that the motor will be happy singing along at a cruise speed of 48-50km/hr without punishing it too hard providing the motor has got the balls like you said.
 
beentryin

beentryin

New Member
Apr 24, 2010
208
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goshen,ohio
i have a 41 tooth on a grubee gt5 and it pulls any hill were i live and screams top end and will take off from dead stop with a little clutch slip. i say 41 tooth and i weigh 200 pounds
 
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