95"QUESTION
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Cruiser
Joined: Nov 2004
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From: Massachuetts
95"QUESTION
DOES THE BIG BORE STAGE 1 KIT CHANGE THE COMPRESSION RATIO, AND IS THERE A DIFFERENT MAP FROM HARLEY WITH THE 25 DEGREE INJECTORS, I POSTED AND EARLIER REQUEST WITHOUT MANY ANSWERS!!
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Joined: Feb 2006
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From: TX
RE: 95"QUESTION
If everything else stays the same, there is a slight compression increase when you go from an 88 to a 95. Simple math tells you that if you "compress" a larger volume into the same size cumbustion chamber, then you have increased the compression "ratio".
You will probably be looking at a difference of 8.9:1 on an 88 to 9:1 on a 95.
I believe HD has new ECM code for the 25 degree injector bikes, however your best bet woulf be getting a tuning device added and properly tuned after the mods. Both PCIII and SERT will do the job for you.
You will probably be looking at a difference of 8.9:1 on an 88 to 9:1 on a 95.
I believe HD has new ECM code for the 25 degree injector bikes, however your best bet woulf be getting a tuning device added and properly tuned after the mods. Both PCIII and SERT will do the job for you.
Banned
Joined: Jan 2006
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From:
RE: 95"QUESTION
Pretty much what PhilM said. I am pretty sure that there is in fact a different flash calibration for the 25 degree injectors. Also, when you do a big bore, you will have options on the compression ratio even with the harley stuff.
nogood o~`o
nogood o~`o
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From: TX
RE: 95"QUESTION
ORIGINAL: asuperheat
the big bore with flat tops raises it to 9.5:1
the big bore with flat tops raises it to 9.5:1
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Elite HDF Member
Joined: Mar 2006
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From: Biddeford, Maine
RE: 95"QUESTION
ORIGINAL: asuperheat
the big bore with flat tops raises it to 9.5:1 the htcc kit raises it to 10.5:1 and yes the maps are diffrent on the injectors.
the big bore with flat tops raises it to 9.5:1 the htcc kit raises it to 10.5:1 and yes the maps are diffrent on the injectors.
Steve
Road Master
Joined: Nov 2006
Posts: 1,227
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From: Central Illinois
RE: 95"QUESTION
Harley-Davidson uses an average for compression ratio's. Advertised compression ratio for a a stock Twin Cam 88 is 8.8:1, 95" with flattop pistons is 9.4:1. This is all based on using a stock head gasket is .052". The SE Cometic gasket has a diferent squish. A stock twin cam 88 with stock head gaskets you can -1.5 for cold calculated compression and add 1.5 for hot calculated compression ratio's because cylinder expansion can be as much as.040. This is why HD SE numbers don't always match. The 25 degree injectors use the same 3.91 gpm as the early 8mm, however have a different spray pattern (tip) and they require 32310-06 download.
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