Safe Cold cranking compression PSI
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Cruiser
Joined: May 2014
Posts: 213
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From: Caledon East, Canada
Safe Cold cranking compression PSI
What is considered the safe Cold Cranking Compression PSI for a "air only" cooled 103 touring bagger capable of running safely on todays gas? My engine is going for a rebuild at the end of season and would like some info to understand.
Thanks
Jerry
Thanks
Jerry
HDF Community Team
Joined: Jun 2006
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From: san antonio
"Safe" for me would be 190-195psi and with compression releases. However, builders are becoming more comfortable with CCP in the 200+psi range these days. The 98" motor in my '05 FXSTD runs at 212psi with no issues; the key is in the tune.
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Cruiser
Joined: May 2014
Posts: 213
Likes: 40
From: Caledon East, Canada
Thanks, according to the Bog Boyz calculator with a 0.010 over bore, Andrews 48H and a .040 head gasket I end up with 10:1 static compression ratio, corrected compression ratio of 9.59:1 and cold cranking compression of 201 at sea level. From what the replys have been this should be a safe combination. I am right is this assumption?
Thanks
Thanks
HDF Community Team
Joined: Jun 2006
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From: san antonio
Are you at sea level? If not adjust. At the CCP compression releases will extend starter and battery life. You did not provide provide the model year so maybe ACRs? If not, manual compression releases should be part of the rebuild plan.
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Cruiser
Joined: May 2014
Posts: 213
Likes: 40
From: Caledon East, Canada
Sorry for leaving out info, 2014 Ultra 103 Air cooled with ACR's. Our home altitude is 300' above sea level, we do however travel west to the Canadian Rockies, Colorado, Montana and points westward
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HDF Community Team
Joined: Jun 2006
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From: san antonio
Adjusted for seal level, you compression looks to be about 9.9 static, 9.5 corrected and 197CCP, very manageable with a good tune. The higher the altitude, the lower the CCP, so traveling to higher alititudes is not an issue. So, keeping compression in this range on the rebuild would be fine iMHO.
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Thread Starter
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Cruiser
Joined: May 2014
Posts: 213
Likes: 40
From: Caledon East, Canada
Thanks, the builder is targetting 9.6:1 (static I am assuming) and using Andrews 48H's. He states this will be a nice reliable yet torquey build to run on crappy Canadian & US gas.
Thanks for the input and clearing things up for me to all.
Thanks for the input and clearing things up for me to all.
HDF Community Team
Joined: Jun 2006
Posts: 12,763
Likes: 2,597
From: san antonio
