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Shaving the stock cylinder head .040


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So why, if you are gonna spend the money to have the stock head redone, would you then run out and buy a coolhead (and craptastic orings)? pick one and be done.

 

I dont understand why everything needs to be so complicated with newbies.

I dont plan to run out and buy a cool head with domes if i get the stock head machined. Im just lookin to set it up once and be done but i dont have alot to spend. Im probably gonna send a stock head to mull eng. and have it done and run it from now on.

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Thats my plan. Ill call them monday and ask them which one they want to work with and send it to them. Ide rather have a stock head worked without the O rings and studs that the cool head requires. I dont plan on changing it out after its together this time. Plus the work they will do will be cheaper too. I pulled the shaved head off today and without doing a squish test it was obvious that the squish is too tight. The detonation on top end was also an indication and after pulling it off im glad that i got the advice here that convinced me to change it out.

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Thats my plan. Ill call them monday and ask them which one they want to work with and send it to them. Ide rather have a stock head worked without the O rings and studs that the cool head requires. I dont plan on changing it out after its together this time. Plus the work they will do will be cheaper too. I pulled the shaved head off today and without doing a squish test it was obvious that the squish is too tight. The detonation on top end was also an indication and after pulling it off im glad that i got the advice here that convinced me to change it out.

 

do you know the specs on your engine? port durations and such? this will be important info.

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What conversion do i use to determine cc volume of the domes? liquid im sure but i dont know the conversion formula. As far as the squish test goes i plan on doing one sunday after i get the caliper to do it. I didnt have all the tools needed to work out all the details when i put it together.

 

You can't go by the cc spec of the domes to be what the trapped volume is. You need to have the engine assembled, with grease around the rings, grease on either side of head gasket, piston at top dead center, and head installed with nuts tightened. You then take a burette filled with kerosene and start filling up the head area thru the spark plug hole. Fill up to the bottom of the spark plug hole. Take note of the ML of kerosene used to fill the head area. 1ml = 1cc. If I know your bore and stroke, I can give you a cc amount that you will need to have, for a certain comp ratio. Understand??

 

Also, for those that said .030" off a stock head is too much for pump gas, aren't fully correct. How efficient your pipe is, how thick of a base gasket used, and amount of ignition timing, are just some of the other factors that will play into wether or not you will be seeing deto. I ran my stock head shaved .030" with Moose Racing base gaskets (thicker than stock) and had .050" squish and no deto with 93 pump gas. Timing was anywhere from stock to +4.

 

I personally wouldn't run over +4 on 93 pump either.

Edited by mopar1rules
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My cylinders are stock with an aggressive trail port job. The port work is shy of a drag port but more than a mild trail port. Advance machine shop in Pa. did the port work and bored the cylinders to 65 mm . I used weisco pro lite pistons with a stock stroke Vitos crank. Im running the stock carbs with .30 pilots and 340 mains . I have K&N filters and FMF gold series exhaust . My jetting is pretty close because my plugs look good and it transitions from the bottom end to the power band smooth and without hesitation. I put a stock head back on it this evening and it runs great but i can feel some loss on the bottom end. The loss isnt enough to be worth the worries of having to little of squish height and always being paranoid about piston to head issues. Im gonna send this stock head to mull engineering when i get the extra cash and get a good set of domes cut in it and have them shave it to specs to keep me in pump gas territory.

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My cylinders are stock with an aggressive trail port job. The port work is shy of a drag port but more than a mild trail port. Advance machine shop in Pa. did the port work and bored the cylinders to 65 mm . I used weisco pro lite pistons with a stock stroke Vitos crank. Im running the stock carbs with .30 pilots and 340 mains . I have K&N filters and FMF gold series exhaust . My jetting is pretty close because my plugs look good and it transitions from the bottom end to the power band smooth and without hesitation. I put a stock head back on it this evening and it runs great but i can feel some loss on the bottom end. The loss isnt enough to be worth the worries of having to little of squish height and always being paranoid about piston to head issues. Im gonna send this stock head to mull engineering when i get the extra cash and get a good set of domes cut in it and have them shave it to specs to keep me in pump gas territory.

more than .035 is to tight for a stock head with stock gasket ,base and head,,,,,,,,,,

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more than .035 is to tight for a stock head with stock gasket ,base and head,,,,,,,,,,

Yea i just went through that with a head that was milled .040 . I was getting detonation on the top end with pump gas. I was lucky and didnt get any damage before i changed it out with a stock head. Im gonna send this head to mull engineering when i get the extra cash.

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more than .035 is to tight for a stock head with stock gasket ,base and head,,,,,,,,,,

Yea i just went through that with a head that was milled .040 . I was getting detonation on the top end with pump gas. I was lucky and didnt get any damage before i changed it out with a stock head. Im gonna send this head to mull engineering when i get the extra cash.

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I took the bike to the spillway in new orleans today and rode for about 4 hours with the stock unshaved head and the timing pulled back to 4 degrees. It ran better than i thought it would and didnt have any detonation issues. I did a compression test and it pumped up 140 psi in both cylinders which seemed odd to me because i thought with a stock stroke and head it should be around 120 or so. Does any body know what the compression should be with stock deminsions? Could my base gaskets be too thin or something? Im not worried about it but it just doesnt seem right to have 140 psi with stock stroke and head.

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