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Old 03-01-2011, 07:08 PM
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Default Shaveing and re chambering a head READ

     

Ok, i have seen a few posts on pistion squish and how to measure and so on a so forth. This is my head that i just got done today. The squish measured at 0.045. I wanted some more compression like we all do. Now you can shave a head and keep the same squish and get more psi like i did. Alot of people go to far with bringing the squish down so far that your bike/ sled actually detonates. I have seen this first hand. What i did was shaved the head 0.010 where the black squiggly lines are. Then i also shaved it 0.010 where the black half circle is. Now you might say how does that increase the compression. Well what you are doing is moving the dome down and keeping the "squish zone" exactly where it was by shaving it the same amount as the gasket surface. I went from 120psi to 154psi with 0.010, not bad. I havent ridden the bike since we still have snow on the ground but i am racing indoors next weekend but i can say it revs alot better and is crisp. Hope this helps

Oh yeah this is on a 05 cr125


http://i268.photobucket.com/albums/j...dss26/head.jpg

Last edited by bbrmotosports; 03-01-2011 at 07:45 PM.
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Old 03-01-2011, 07:29 PM
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thats awesome!! once i get mine done, ill measure the squish (i actually somewhat got what that other dude mentioned about the solder and stuff) and ill have to get mine shaved! is it a big improvement?
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Old 03-01-2011, 07:34 PM
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Just got it together 20 mins ago, it's alot crisper thats for sure. I'll post after i ride. Thats all i use is solder to measure. You just gotta make sure you tell your machine shop what you want. Not just shaving the gasket surface.

---------- Post added at 07:34 PM ---------- Previous post was at 07:33 PM ----------

If you want the number to my machine shop pm me.
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Old 03-01-2011, 07:42 PM
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what bike do you ride?
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Old 03-01-2011, 07:45 PM
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05 cr125
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Old 03-01-2011, 08:07 PM
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alright ill see what i can do with my rm
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Old 03-02-2011, 12:18 PM
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lowering the roof and keeping the squish area the same will certainly raise the compression. old rule of thumb was to have 60 percent of your combustion chamber covered by the squish area, and 40 percent by the dome. if you want something higher reving you start working the other way, where more like 50/50 or 40 percent is in the squish and 60 percent is in the dome.
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Old 03-02-2011, 03:52 PM
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man i love the look of milled metal, and yea ill talk to my local shop see how much it costs
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Old 03-02-2011, 06:02 PM
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Default Oooh Fun, this is what i love to see...

Awesome to see that poeple are taking there two strokes as a tuning sport...
this is one of my favorite parts of motocross.

Remember that with increased Compression, you need to run higher octane that is more stable and more resistant to pre-igniting. Also youd be best with adjusting the stator plate and adjust the timing for the fuel your running as well. ossagp Knows much, and respected for his knowledge. his thoughts on the dome are pretty square. alot of things can be done in this area of the motor. this area is everything for a two cycle performance motor.

What are you trying to gain in the motorcycle?
where do you want the power?
what type of racing is the bike going to see?

With that in mind there is a huge handful of things that can be done...
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Old 03-02-2011, 06:10 PM
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Quote:
Originally Posted by Pretendo View Post
Awesome to see that poeple are taking there two strokes as a tuning sport...
this is one of my favorite parts of motocross.

Remember that with increased Compression, you need to run higher octane that is more stable and more resistant to pre-igniting. Also youd be best with adjusting the stator plate and adjust the timing for the fuel your running as well. ossagp Knows much, and respected for his knowledge. his thoughts on the dome are pretty square. alot of things can be done in this area of the motor. this area is everything for a two cycle performance motor.

What are you trying to gain in the motorcycle?
where do you want the power?
what type of racing is the bike going to see?

With that in mind there is a huge handful of things that can be done...
exactly, before i can shave my cylinder head first i need to knock the dents outa my pipe... looong road ahead of me, oh well!! and yes, ossagp is a very knowledgable trustworthy person, i can tell.
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Old 03-02-2011, 06:16 PM
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I paid my guy $58.00. And i run race fuel. i have never advanced the timing yet. I'm going to wait until summer comes around since i can only ride indoors right now so i really cant be playing around too much.
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