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!!

 

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.

 

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

 

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.

 

Not with with stock heads and gaskets.... "maybe" 9.1:1 (depending on actual CC size on a given set of stock heads), but not 9.5:1.

[sm=noooo.gif]

 

Don't believe everything you read. That is according to the SE catalog..........it's false info.

Steve

 

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.