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| Heads and Cylinders All about your porting, compression, rings, cylinder and piston modifications
to your bicycle engine |
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06-24-2008, 08:08 PM
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Motorized Bicycle Elite Member
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Join Date: Jun 2008
Location: Australia
Posts: 127
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Machining the head/ Boosting compression
I am considering machining the top of the cylinder (the head) down by a millimeter or two on a lathe to boost compression. Has anybody tried this? There is a bloke from Australia who has apparently with success.
Shouldn't be too difficult and should work fine... bit of a risk tho! Hmmmmm
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06-24-2008, 08:10 PM
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Motorized Bicycle Elite Member
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Join Date: Jun 2008
Location: Australia
Posts: 127
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Re: Machining the head/ Boosting compression
Here is the link... Check out "Lisdale Flyer" what a BEAST!!
ZBox engine innovations 2008
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06-24-2008, 10:54 PM
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Motorized Bicycle Elite Member
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Join Date: Jun 2008
Location: Longmont, CO
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Re: Machining the head/ Boosting compression
I was just thinking about this today, wondering if it could be done.
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06-25-2008, 05:57 AM
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Motorized Bicycle Elite Member
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Join Date: Jun 2008
Location: Australia
Posts: 127
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Re: Machining the head/ Boosting compression
Shouldn't be too hard Just take the cylinder to a metal turner. I think it would be a good idea to tread cautiously. The extra compression might rip a head bolt right out of the engine block! I stripped the engine block thread just by over tightening a while back, luckily I had it heli-coiled back in place
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06-25-2008, 07:28 AM
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Godfather of Motorized Bicycles
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Join Date: Jan 2008
Location: Ashtabula county, Ohio
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Re: Machining the head/ Boosting compression
I don't know about a "mm or two". That would be a bit excessive.
3mm would be 1/8th of an inch!
Math for the Toolbox. SAE to Metric Conversion.
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If it ain't broke, and you mess with it long enough, it will be.
Last edited by Bikeguy Joe; 06-25-2008 at 07:31 AM.
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06-25-2008, 08:49 AM
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Master Bike Builder & Forum Sponsor
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Join Date: Dec 2007
Location: Duvall, WA PNW
Posts: 3,291
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Re: Machining the head/ Boosting compression
Back in the day we would surface grind or mill heads.....dunno about the head in a lathe....
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06-25-2008, 09:51 AM
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Super Moderator
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Join Date: Jan 2008
Location: Ptown, Texas
Posts: 2,282
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Re: Machining the head/ Boosting compression
Norman has a piece of glass with sandpaper glued to it that he uses. It removes metal real nice and slow. He keeps it wet and soapy...................
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Life isn't like a bowl of cherries, it's more like a jar of jalapenos, what you do today might burn your butt tommorrow............
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06-25-2008, 09:55 AM
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Master Bike Builder & Forum Sponsor
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Join Date: Dec 2007
Location: Duvall, WA PNW
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Re: Machining the head/ Boosting compression
That's where I'm going, the Norman way!!
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06-25-2008, 10:09 AM
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Santa Cruz Scooter Works
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Join Date: Jan 2008
Location: Nor*Cal
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Re: Machining the head/ Boosting compression
We done a few and the best one we did was around 70 thousand of an inch. We even redomed one and it works for a little bit but we found out the the head bolts (which are made of cheap metal) stretches. Then leaks and blown head gaskets occur.
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06-25-2008, 10:41 AM
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Master Bike Builder & Forum Sponsor
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Join Date: Dec 2007
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Re: Machining the head/ Boosting compression
Quote:
Originally Posted by Easy Rider
We done a few and the best one we did was around 70 thousand of an inch. We even redomed one and it works for a little bit but we found out the the head bolts (which are made of cheap metal) stretches. Then leaks and blown head gaskets occur.
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More good info. Note to self, get new studs.
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