Is Head shaving a mod?

Nnn

Member
Mar 15, 2018
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I have a 66cc motor that has a warped cylinder head due to my idiotic and uneven tightening. Now unless I tighten the head bolts really tight it will leak oil from the head and loose compression. I was wondering if it would even be worth it for me to sand down the head just enough so I don’t have to over tighten my head bolts and would I gain any power. I also hear this may not be good for my engine. What are your thoughts?
 

Nnn

Member
Mar 15, 2018
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This is also my only cylinder head and I’m most likely not buying another one.
 

wheelbender6

Well-Known Member
Sep 4, 2008
3,988
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TX
Sanding won't help. You could have a machine shop try to shave it flat, but a new head will be cheaper.
 

mrfubs

Member
Jun 13, 2013
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michigan
I doubt its warped but you can sand it down with no problems get yourself a 1ft by 1ft piece of sandpaper. Not rough. And set the sandpaper down on a known flat surface and rub the cyl head In a circular motion.
You most likely wont sand the head down enough to increase the compression to the point where it would be noticeable power wise.

You could also just try a cooper headgasket instead of the stock alloy.
Also you could go to the auto parts store and buy what's called copper gasket spray made by permatex, coat both sides of your gasket and then install it. It's great stuff
 

Tyler6357

Well-Known Member
Mar 15, 2012
1,142
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Santa Barbara, CA
Sanding down your head will only ruin your head. You can take the cylinder off and send the cylinder top with a piece of glass and sandpaper method, use very light girt sand paper and do it slowly in a figure 8 pattern on a flat surface keeping the cylinder as straight as possible. Don't take off too much or the piston will hit the head. You want the squish gap to be between .025"- .035". However, if the head is warped just get a new one, a stock head is $8.

https://www.ebay.com/itm/47mm-Motorized-Bicycle-Cylinder-Head-Piston-fit-for-80cc-Gas-Bike-Engine/263188222891?hash=item3d473d93ab:g:rbwAAOSwPCFZrgax&_sop=15&_pgn=3&_sacat=0&_nkw=motorized+bicycle+head&_from=R40&rt=nc
 
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Venice Motor Bikes

Custom Builder / Dealer/Los Angeles
Mar 20, 2008
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Yes... You can sand a stock head flat again!! (I do it all the time).

Put some sandpaper on a piece of glass & sand it until you see the sealing ring has sanding marks all the way around.

Only torque the stock head to 12 ft/lbs so that it won't warp again!
 
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