Too much compression

[hogrdr]

I have a 2001 Heritage Softail with Screaming Eagle crank. I had case machine for 4 1/8 Pistons. I had a 117 S&S kit installed come to find out the cylinders was not true. Have them bored 10 over with 10 over new Pistons. The Pistons are set at .003 above deck..020 base gasket and .040 head gasket. My cranking compression has 225. I put on CVO 110 heads CC. 92. 585 cam. Is there a way to bring my compression down? Engine pings. Thanks

[rigidthumper]

1) An adjustable ignition is your friend.
2) Your numbers don't add up, unless the crank-cam timing is off.
3) A .010" over 117 flat top, .003' proud, with a 40 thou thick head gasket and 92 cc heads is 10.46:1, and that cam (45° close) should have ~196 PSI CCP.

[MikeL]

I went to this site
http://bigboyzheadporting.com/TwinCamComp.htm
and plugged in your specs and got 10.34 static compression, 9.31 corrected compression.Flat top pistons? Was the compression test done hot? Retest compression with another test gauge to confirm 225 is way high
Is the bike carb? Is it fuel injected?
Your going to have to dial back on spark timing. Carb bike your gonna need an after market module that is spark adjustable. If it's a M/M P/C 3 and god help you with that.

                                                                                                                                                                    MIKE

[hogrdr]

1) An adjustable ignition is your friend.
2) Your numbers don't add up, unless the crank-cam timing is off.
3) A .010" over 117 flat top, .003' proud, with a 40 thou thick head gasket and 92 cc heads is 10.46:1, and that cam (45° close) should have ~196 PSI CCP.

I will check my timing today

[hogrdr]

1) An adjustable ignition is your friend.
2) Your numbers don't add up, unless the crank-cam timing is off.
3) A .010" over 117 flat top, .003' proud, with a 40 thou thick head gasket and 92 cc heads is 10.46:1, and that cam (45° close) should have ~196 PSI CCP.

I will check my crank cam

[hogrdr]

I went to this site
http://bigboyzheadporting.com/TwinCamComp.htm
and plugged in your specs and got 10.34 static compression, 9.31 corrected compression.Flat top pistons? Was the compression test done hot? Retest compression with another test gauge to confirm 225 is way high
Is the bike carb? Is it fuel injected?
Your going to have to dial back on spark timing. Carb bike your gonna need an after market module that is spark adjustable. If it's a M/M P/C 3 and god help you with that.

                                                                                                                                                                    MIKE

yes the cranking compression was checked hot and I did have my compression tester check and it was good

[hogrdr]

I went to this site
http://bigboyzheadporting.com/TwinCamComp.htm
and plugged in your specs and got 10.34 static compression, 9.31 corrected compression.Flat top pistons? Was the compression test done hot? Retest compression with another test gauge to confirm 225 is way high
Is the bike carb? Is it fuel injected?
Your going to have to dial back on spark timing. Carb bike your gonna need an after market module that is spark adjustable. If it's a M/M P/C 3 and god help you with that.

                                                                                                                                                                    MIKE

carbureted

[Hossamania]

Are you running stock ignition?

[Don D]

Only seen it once on an early 103 with the same Jims crank. The flat was  misoriented.

[hogrdr]

1) An adjustable ignition is your friend.
2) Your numbers don't add up, unless the crank-cam timing is off.
3) A .010" over 117 flat top, .003' proud, with a 40 thou thick head gasket and 92 cc heads is 10.46:1, and that cam (45° close) should have ~196 PSI CCP.

cam crank timing is correct

[Ohio HD]

I went to this site
http://bigboyzheadporting.com/TwinCamComp.htm
and plugged in your specs and got 10.34 static compression, 9.31 corrected compression.Flat top pistons? Was the compression test done hot? Retest compression with another test gauge to confirm 225 is way high
Is the bike carb? Is it fuel injected?
Your going to have to dial back on spark timing. Carb bike your gonna need an after market module that is spark adjustable. If it's a M/M P/C 3 and god help you with that.

                                                                                                                                                                    MIKE

yes the cranking compression was checked hot and I did have my compression tester check and it was good

How was the compression tester checked for accuracy?

[hogrdr]

Are you running stock ignition?

using twin Tech tc88

[Hossamania]

Are you running stock ignition?

using twin Tech tc88

What are your settings?
Have you checked for vacuum leaks?

[hogrdr]

1 timing -1 slope. That is where I get the least ping. I tried timing 1 and all the slopes timing to all the slopes and 1 and 1 was the best. Going to take it in and have a dial indicator put on it and see where I'm at

[ThumperDeuce]

Put a cam in with more overlap and enjoy the ride.

[Hossamania]

Might have to do an afr check to see where you're at.
Which carb are you using?

[Hossamania]

Fuel, have you tried different gas stations, brands? Running premium, 91 - 93 octane?

[hogrdr]

Fuel, have you tried different gas stations, brands? Running premium, 91 - 93 octane?

I have a AFR on the bike at cruising speed it runs between 34 and 32

[hogrdr]

Fuel, have you tried different gas stations, brands? Running premium, 91 - 93 octane?

I have a AFR on the bike at cruising speed it runs between 34 and 32

93 octane yesterday I tried 100% gas no changes

[hogrdr]

Might have to do an afr check to see where you're at.
Which carb are you using?

what cam do you recommend

[hogrdr]

Might have to do an afr check to see where you're at.
Which carb are you using?

45 Mikuni and I have an AFR she runs at 34 32 cruising speed

[hogrdr]

1) An adjustable ignition is your friend.
2) Your numbers don't add up, unless the crank-cam timing is off.
3) A .010" over 117 flat top, .003' proud, with a 40 thou thick head gasket and 92 cc heads is 10.46:1, and that cam (45° close) should have ~196 PSI CCP.

[rigidthumper]

Remove the plugs, set rear to TDCC, and verify the flat on the crank is pointing exactly inline with the center of the rear cylinder with a t-square.
That is a rough check on the crank flat being machined properly.

[hogrdr]

Fuel, have you tried different gas stations, brands? Running premium, 91 - 93 octane?

I have a AFR on the bike at cruising speed it runs between 13.2-13.4

[MikeL]

Check for case sumping. This could add load on the engine causing detonation.

                                                                                                                                                               MIKE

[Don D]

225 psi cranking ccp, carbureted, the likely cause flat on the crank not properly oriented. The fix is to locate tdc with a piston stop and use a timing wheel, indicator at the lifter, and determine if the valve events match the timing specification. Based on the findings the timing can be changed by tooth changes and possibly an offset key if needed. Timing would have to be 10+ degrees off to show the results being demonstrated.
I am sure this has happened before not just the one time I experienced this in 2004.

[Hillside Motorcycle]

IF, the compression is too much, those pistons have enough wall thickness to dish them, and S&S offers a dished version.
Easy to accurately pull 4-5cc's/more from your pistons inexpensively.

[Don D]

They are now dished -3.5cc, heads 92cc, .037 squish. I verified his gauge is accurate

[sfmichael]

Put a cam in with more overlap and enjoy the ride.

   

If crank is oriented correctly change cams. Add 10* of duration and bike should crank about 210psi

S&S 625 should be a good choice if you have the springs for it

[Admiral Akbar]

So the cam is a SnS 585 or SE 585?

225 hot ain't that bad, retard the timing.  I run 220 cold cranking compression in a 11.3 to 1 motor.  Runs fine except that the early SnS crank rebuilt by dark horse will eventually go bad. Not DH's fault, more SnS using a 1 1/2 inch crank pin.

[Don D]

S&S 585g. Jims/SE crank. I wrote a custom curve for it, 20deg max at 4500 rpm with a lot of dip in high throttle/map pressure lower rpm areas. Still pinged. No more need to crutch this build, the root cause will be found and fixed.

[Admiral Akbar]

What plugs you running?

[itsafatboy]

I think the 585 cam is a little short for a 117" ,  i like the woods TW9BG ,  i have a 116" and the cam likes 11 + comp ,  it closes at 50 and longer duration  , it does have a .630 lift so would have to have springs for it ,

[Admiral Akbar]

I think the 585 cam is a little short for a 117" ,  i like the woods TW9BG ,  i have a 116" and the cam likes 11 + comp ,  it closes at 50 and longer duration  , it does have a .630 lift so would have to have springs for it ,

IIRC the SnS 124lc uses a 585.

[Don D]

This motor has 10.4:1 static compression,  fluid measured, cylinder lengths adjusted both same piston to deck height, .037 squish.

[dsvracer]

How about just enlarging the combustion chamber by 4-5 cc's. pretty simple to do and it doesn't cost much. no new parts needed.

[harpwrench]

With a 60 degree ex open cam i would want to fix the problem, would think it's probably way down on power too if it's way advanced from there

[Don D]

Fix the problem,  root cause, thank you.