Twin cam engine upgrade
#1
10-20-2006, 11:30 AM
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Twin cam engine upgrade
Seriously thinking of upgrading the engine on my 05 Fatboy with a 95ci big bore kit,S&S 510 gear drive cam kit & SERT. Already running V&H pipes and SE air cleaner. Does anybody have this combination to let me know what or have good knowledge of this combination. (Do alot of two up riding
#2
10-20-2006, 12:22 PM
RE: Twin cam engine upgrade
The 510 cam is a great cam, however you do need to have a compression range of 9.5-9.8 with that cam to really allow the cam to perform correctly. A flat top SE piston with stock heads will yeild approx 8.9.1 compression. Mainly due to the reason of the chambers on the heads being in the 86-88 cc range. You can install a .030 cometic head gasket that will help but you will still need to mill the deck surface of the head. Porting will greatly help that cam pull harder for you as well.
If you decide not not to anything with the heads I would then suggest a andrews 26 cam as you will be much closer to a comp ratio matched to the cam. The 26 is a great little cam that will make some very good tq numbers and is no slouch. We use the 26 in the 95 inch bagger kits. Choosing a cam that is larger than needed is a common mistake and ends up with a engine that makes power but late in the rpm band, leaving the normal riding rpm area soft.
You could also use a dome piston to raise the comp level with the stock head. That is another option, But stay away from the cast SE piston, they can be more trouble than they are worth as many time you have issue with piston to head clearance and the piston then needs to be machine along the sides of the dome at that point you have spent the money of what a forged piston would cost you.
The piston that we use in the 95 inch kits is a CP piston that is forged and will offer you 9.7.1 with a .030 head gasket with a 85cc chamber. So you could get very close to the "sweet spot" on compression with the 510 cam with no head machining at all. We charge $50 to cc and deck heads as I have seen that to be a common charge for the service.
GOOD LUCK with the new build. Always nice to have a bit more power on tap.
If you decide not not to anything with the heads I would then suggest a andrews 26 cam as you will be much closer to a comp ratio matched to the cam. The 26 is a great little cam that will make some very good tq numbers and is no slouch. We use the 26 in the 95 inch bagger kits. Choosing a cam that is larger than needed is a common mistake and ends up with a engine that makes power but late in the rpm band, leaving the normal riding rpm area soft.
You could also use a dome piston to raise the comp level with the stock head. That is another option, But stay away from the cast SE piston, they can be more trouble than they are worth as many time you have issue with piston to head clearance and the piston then needs to be machine along the sides of the dome at that point you have spent the money of what a forged piston would cost you.
The piston that we use in the 95 inch kits is a CP piston that is forged and will offer you 9.7.1 with a .030 head gasket with a 85cc chamber. So you could get very close to the "sweet spot" on compression with the 510 cam with no head machining at all. We charge $50 to cc and deck heads as I have seen that to be a common charge for the service.
GOOD LUCK with the new build. Always nice to have a bit more power on tap.
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