Couple questions on SRX ??

007redline

007redline

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Does anyone know the stock Squish on a 1998 and 2001 SRX 700 ???

what's everyone running for compression?

Is there an easy'r way to check squish besides a piece of sawder...Keep on getting different readings... Obviously ya want sawder paralell to wrist pins eh..anyone...lol ?? This is driving me nuts...Ahhh...bahaha
 
don't let the solder fall into the cylinder.Make sure piston is cold also or else your solder will melt on top of it. HAha..just kidding.I have never tried the solder trick myself.Good soldering to you.
 
don't know stock squish. I have .055" squish on my '99, cut the heads to make it that, was at .064-.067 before cutting. Running about 125 psi comp. cold, on my comp. gauge anyway, they will vary a bit from one to another.
 
you need 2 pieces of solder to check squish & get a correct reading. one above each end of the piston pin. this keeps the piston from rocking left or right in the bore & giving a false reading. stock is about .062.
bob
 
cranking pressure will vary on the same compression gauge & engine depending on 2 factors, 1.) air temperature ( density ) & 2.) speed @ which engine is cranked over.
bob
 
007redline said:
Thanks just got er done .056 across the board...lucky 120 p.s.i cheap gauge..lol

How do you check your volume/ratio?
Click to expand...

If the only mods to your heads was to remove .005"-006" from mating surface that would reduce your combustion chamber about .5cc + without any port changes give you approx 5psi increase in cranking compression .

This reduction in cylinder head volume would give you a full stroke compression ratio of approx 12:1.

[IMO : about the limit for premium fuel]
 
to find the trapped volume out for your engine, you need to seal the rings w/grease and have piston at TDC. then bolt the head up, w/whatever head gasket you use during actual engine operation, and fill up thru the spark plug hole, w/kerosene, using a burette. fill up to the top of the spark plug hole, check burrette for how much kerosene went in, and subtract 1.8cc for the spark plug hole and then add .2 to .3cc for the spark plug volume around the ground wire. this is your trapped volume. you can also fill to the bottom of the spark plug hole too, but its just harder to see if your right there.
 
am i thinking this through right pertaining to porting and compression ratio, this is how i'm seeing it:
if you've raised your exhaust port during porting and done nothing to heads you'd lower your compression ratio because you'd now be compressing less cyl volume into the same head volume
if I'm looking at this all wrong then please correct me
 
staggs65 said:
am i thinking this through right pertaining to porting and compression ratio, this is how i'm seeing it:
if you've raised your exhaust port during porting and done nothing to heads you'd lower your compression ratio because you'd now be compressing less cyl volume into the same head volume
if I'm looking at this all wrong then please correct me
Click to expand...

You are absolutely correct on this, but this is the "corrected" compression ratio or trapped compression. Yamaha , a lot of other manufacturers, and engine builders use this as it is really the critical calculation for indication of what the engine is really working with for cylinder combustion/pressures.

Uncorrected comp ratio is based on the full stroke of an engine...more for we "laymen" lol!

For example: My trail ported 2002 SRX full stroke comp ratio = 12.0 : 1
.....................................................corrected comp ratio = 6.1 : 1
 
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staggs65 said:
thanks bob
so 6.0:1 corrected would probably be about the limit for quality pump gas?
Click to expand...

I corrected my post...its actually 6.1 : 1.
Honestly I have to admit ignorance on what is the max corrected comp ratio you can run. I have experience with the uncorrected ratio method . That would be a question for the "Gurus" again like Mr Viper and I am sure it varies with other factors as well.
 
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