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[Jswerve]

Factory specs states stock compression is 9.2:1 I was wondering if that was static compression or corrected?

Jesse

[prodrag1320]

static

[Jswerve]

Thank you. Just comparing my new compression to stock now I can do apples to apples.

[Unbalanced]

JSwerve you should look at the calculator on bigboyz site and do the math your self.

http://www.bigboyzheadporting.com/TwinCamComp.htm

If you do use the 110 motor they have with the 255 cam and the cc of the heads is 95 cc can be 94 but for sake of getting close.
The headgasket is .043 but you can use .045 thick
Most of the 110's are in .004-.008 in the hole with the pistons.   you can use 0 deck but very few if any are there.


If you go by the calculator you will find a different answer than the one that has been given.   One other thing to note is in the 5 different cvo 110's I have owned none have ever cranked less than 205 and have been between 205-220 as a stock motor.   Which would mean more compression than the calculator is showing.

[Jswerve]

JSwerve you should look at the calculator on bigboyz site and do the math your self.

http://www.bigboyzheadporting.com/TwinCamComp.htm

If you do use the 110 motor they have with the 255 cam and the cc of the heads is 95 cc can be 94 but for sake of getting close.
The headgasket is .043 but you can use .045 thick
Most of the 110's are in .004-.008 in the hole with the pistons.   you can use 0 deck but very few if any are there.


If you go by the calculator you will find a different answer than the one that has been given.   One other thing to note is in the 5 different cvo 110's I have owned none have ever cranked less than 205 and have been between 205-220 as a stock motor.   Which would mean more compression than the calculator is showing.

Harry thanks I went over this with Sachs today when I had him on the phone 

[Unbalanced]

I noticed an inconsistency in the calculator as it defaults to a smaller bore which is the 107 when you pick a 110 so I changed it and I added .005 for the pistons being in the hole.
You will see your still not at 9.2 static and the cranking compression from what has been seen is not even close (lower) than I have ever seen on mine or friends bikes or that has been posted.

[Unbalanced]

Harry thanks I went over this with Sachs today when I had him on the phone 

Great hopefully you are all set then.   

[Jswerve]

Great hopefully you are all set then.

Yes sir Thank you for sharing.

Jesse

[Colonel Sanders]

I've been wondering the same thing.  The BigBoyz calculator would suggest that the stock static CR is over 10:1 if a CCP of 205+ is correct.  Even if we assume 94cc chambers then you'd need a small piston dome (like 3.6cc) for it to be 10:1.

So what's the truth?  Is this engine 10:1 from the factory?  Are the pistons slightly domed?  I sure don't understand how it can be 9.2:1 with the CCPs I keep seeing reported.

[Unbalanced]

Colonel,

You might consider giving a call to Steve at GMR, I believe he has a cam doctor to tell if the specs on the cam are actual or not and go from there.  Maybe he has checked a set already 

[HILLSIDECYCLE.COM]

I've been wondering the same thing.  The BigBoyz calculator would suggest that the stock static CR is over 10:1 if a CCP of 205+ is correct.  Even if we assume 94cc chambers then you'd need a small piston dome (like 3.6cc) for it to be 10:1.

So what's the truth?  Is this engine 10:1 from the factory?  Are the pistons slightly domed?  I sure don't understand how it can be 9.2:1 with the CCPs I keep seeing reported.

At 9.2 cr, which they hover at pretty close, the only other factor is the super-short emmission school-bus cam, that'll create that accellerated ccp, which it does.
No domes, and acutally about about a -1.5 cc with the valve reliefs.
Scott

[Colonel Sanders]

Yeah, I'll bet Steve has Cam Doctored one.  However, even an intake closing of 10 degrees wouldn't explain the 200-220 CCPs we're seeing.

Thanks for the first hand info, Scott.  It sounds like you're saying that the intake closing event isn't the only determining factor.  In addition to the super short intake duration, perhaps the ramp rates (slow in this case I'm assuming) play a part as well.

What still gets me is that I'm also noticing people doing cams only and coming up with CCPs that, again, suggest higher than 9.2.    But if Scott says they're 9.2:1 stock then I'm sure he knows what he's talking about.
 

[Colonel Sanders]

FWIW, my bone stock (1550 miles) CVO Limited had the CCP checked this morning and showed 224/222.  I'm still not sure how the heck a 25 intake closing does that with 95cc heads and -1.5 pistons.  The 95cc heads were verified to be just that on both heads in my case, btw.  Super slow cam ramp rates perhaps?  chit if I know.

Gonna shave the heads 35 thousandths and pop in a set of T-man 600sm cams (39 IC) so we'll see where the CCP lands after that.