compression

What purpose motor

Is this a race motor or a trail motor? I am not a motor builder my any means but I have had a few experiences with this stuff. Have you considered relaxing the squish angle to 13 degrees which will do a couple of things. First, it will lower your compression a little and second it will keep the burn more in the middle of the piston and make the exhaust edge of the piston less likely to melt off. Just a thought.

Madmatt
 
srx 600 head is 21cc

srx700 head from 98-99 is 26cc

there is a +/- spec of 5% meaning it can be 5% smaller then what i listed or larger, this is why you should cc heads and then cut them all to the same spec, then cut uyour squish angle and set up clearances. :rulez:
 
like mr viper explain this is exactly what i did ... now i just try to take some heat out of the exhaust side piston ... ill try to increase the squish clearance and add some angle a little
 
Let me know how things go. I'd be interested in hearing.

But, Does anyone know the stock Band width, and angle of a stock 98 srx 700cc Head?
 
Mopar, I got some measurements, But I don't know the angle. I was wondering if any out there knows how to get the angle? I know the band width, Squish... But I want to confirm my squish angle. Any help?
 
Hey Modsrx,

Would you happen to know the CC's of your head, I've got some formulas, But I want some of your numbers.

Our heads have very similar Band widths, You have WAY more compression, and TOO little of an angle.

I have 11-11.5mm Band width, 17-19 Tapered Angle.

Please if possible, send me your cc.
 
98700 said:
Would the band width be much different in the 98-99 heads?
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i don't think soo. i don't have the '98 700 heads off my spare motor to look at or measure. i have a set of '01 700 heads laying around i could measure tho.

just a thought modsrx, what about getting your pistons coated by swain tech? you could have the domes tbc coated and the skirts coated w/pc9. that might help your piston crown to survive a little more heat. the pc9 would reduce the friction on the piston skirts.
 
i will drop back some compression a little and i will see from there the result...for the cc of the 600 heads i can't remember i made them last year and i got bad memorie .. but they are remove i will check them :winterrul
 
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modsrx said:
i will drop back some compression a little and i will see from there the result...for the cc of the 600 heads i can't remember i made them last year and i got bad memorie .. but they are remove i will check them :winterrul
Click to expand...

Same here, But please let me know. The stock 600cc head is 21cc's. But you had your's shaved. Get back to me ASAP! I'm having my heads done tomorrow, and DOn't want the same issues you're having. And I need that number to fill in my Formulas.

Nik!
 
well its have been shaved in squish and in dome to increase the volume so can't really remember.. i will go back with almost stock heads i will see the difference ..u can try that but i already burn 4 piston make sure they will make them correctly little things seem to do big stuff :2strokes:
 
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I just cc'ed mine, They are 24cc each. They are 98 heads, with some work done to them. 11-11.5mm squish band, and angle cut. So they have 2cc less than stock 98 heads.

I have 10.66:1 compression (5.98:1 REAL compression)
Stock 98 heads have 9.92:1 Compression (5.6:1 REAL compression)

I'm trying to get it down to 11.54:1 compression (6.44:1 REAL compression) OR 22cc Domes!
 
well its just a try i do now to see if i will be able to run the engine with the perfect jet size without melting piston :_))
 
Yeah, I'm just currious to see what cc your head is so I know not to go near that compression ratio. And to find the compression ratio I need to know the cc.
 
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