Milling a 4 stroke 49cc head

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AuntySpam

AuntySpam

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May 20, 2012
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Hi. Way back in July 2010 someone named Chipmonger asked if he could mill his 49cc 4 stroke engine head. Someone replied, "What 4 stroke engine do you have? What kit or gearbox? The Honda GX50 and the Chinese copy have a one piece head and cylinder." I was thinking about getting a Huasheng 49cc kit to put in my cruiser bike. I, too, live in Arizona where the limit is 48cc. Was that person saying that because the head and cylinder are 1 piece, the head can't be milled? Because that's exactly what I was thinking of doing. Is there any other way to lose that 1 cc if that won't work, like putting in a different piston with a bigger top or ??? Any help anyone can give me would be very much appreciated. I don't have much money, and I want to have all my ducks in a row before I buy something I can't use.
 
Mr. Minecraft

Mr. Minecraft

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Jan 13, 2012
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If you are only doing it for the 1cc that makes it 'illegal', then it is completely unnecessary. No one will hassle you for riding the MB, and even if some old crotchety man chases you with his cane and calls the cops, the cops would NEVER spend the time and effort to check to see if your engine is 1cc over the limit.

If you are REALLY worried about it, buy a cheap label maker and print a 48cc sticker, then slap it on the pullstart cover.
 
MotorBicycleRacing

MotorBicycleRacing

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Jul 28, 2010
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There is no cheap or practical way to reduce the 49.4 cc 4 stroke
motors to 48 cc which would make them legal in AZ.

There is no head to mill as the motors have a one piece head and cylinder.

AuntySpam said:
Hi. Way back in July 2010 someone named Chipmonger asked if he could mill his 49cc 4 stroke engine head. Someone replied, "What 4 stroke engine do you have? What kit or gearbox? The Honda GX50 and the Chinese copy have a one piece head and cylinder." I was thinking about getting a Huasheng 49cc kit to put in my cruiser bike. I, too, live in Arizona where the limit is 48cc. Was that person saying that because the head and cylinder are 1 piece, the head can't be milled? Because that's exactly what I was thinking of doing. Is there any other way to lose that 1 cc if that won't work, like putting in a different piston with a bigger top or ??? Any help anyone can give me would be very much appreciated. I don't have much money, and I want to have all my ducks in a row before I buy something I can't use.
Click to expand...
 
MotorBicycleRacing

MotorBicycleRacing

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AuntySpam said:
Darn. I guess I'll have to go with a smaller (34cc ?) motor. Thanks for your input!
Click to expand...
I really wouldn't worry about the extra cc. The size of the motor
is not shown on it except for some tiny print on the EPA label.

It is highly unlikely that a cop is going to ask you.
The cops are more focused on busting you for going over 20 mph.

There are not many 49 cc 4 strokes in Arizona, mainly 48 cc and quite
a few 66 cc 2 strokes.
The case you quote was very rare and he foolishly admitted that his
motor was over 48 cc to the cop.
 
Velodrome

Velodrome

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May 27, 2011
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I agree, Unless your on the local cops "list" they wont care a bit bout 1cc I have had no problem riding about with my Felt Twin and the HS motor; even with an open Phantom exhaust ( not really very loud anyways ) You have some serious hills out your way and at 6000' or so you'll need the extra displacement of the 49cc. NOW. If you were doing a HF 212 I'd be concerned here in 48cc Arizona land. azbill runs a 99cc HF in Fountan hills and the local PoPo hasnt messd with him in forever. He's kindof a legend out there though. They all know him and leave him alone. Taxi's his grandkids to school up and down the hills in a trailer behind the bike. :)
 
AuntySpam

AuntySpam

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May 20, 2012
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Thanks, everybody! Encouraging words. Maybe I will go with the Huasheng . . . . This is a great forum, by the way. I've learned a lot already!
 
racie35

racie35

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Nov 17, 2012
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just so you know in the future..........milling a head doesnt lower your engines cc.......it lower the cc volume of the head increasing compression...so you end up with a smaller chamber your squishing your already 49cc into.....engine cc i determined by bore and stroke...you wouldnt be changing that by shaving the head.
 
moonerdizzle

moonerdizzle

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Jun 28, 2009
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racie35 said:
just so you know in the future..........milling a head doesnt lower your engines cc.......it lower the cc volume of the head increasing compression...so you end up with a smaller chamber your squishing your already 49cc into.....engine cc i determined by bore and stroke...you wouldnt be changing that by shaving the head.
Click to expand...
on a push rod motor you can mill the deck which will decrease cc size some what while increasing compression
 
Y

young grease monkey

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Sep 20, 2011
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i think there is a word for what you are experiencing... paranoia! the cops will never mess with you unless ya go too fast or do something stupid on your bike, let alone check the inside of the engine. they don't care about 1cc unless they already got ya for something else and want to find out what else they can get you for. milling the head on any engine will not change the cc's. only things that can change the cc's are piston size and stroke length. and you can mill the head on a one piece, ya mill the bottom of the jug to lower the entire top end closer to the piston. i would do that anyway if you are at high elevation to get more power. get the hs, it will serve you well
 
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