inceased compression ratio

[Guest]

I have a 4-1/2 stroke x 3-7/16 bore motor It has s&s 2800 ser. 8.5:1 CR pistions .I works well with the exception of occational hard starting due I think to the long duration cam I would like to Increase CR to 9;1 or 9.5:1 any thoughts?

[Cotten]

Guest!

My first thought is that something else makes it hard to start than compression: My second thought is that you would have a hard time finding decent fuel for the higher compression.

....Cotten

[rrhawg]

I have a 4-1/2 stroke x 3-7/16 bore motor It has s&s 2800 ser. 8.5:1 CR pistions .I works well with the exception of occational hard starting due I think to the long duration cam I would like to Increase CR to 9;1 or 9.5:1 any thoughts?

You can run a higher compression with the longer duration cams, as they won't build their peak compression until the higher rpm's. Depending on what you run for an ignition can also make a difference in weather it will ping or not, and how much.
Rich

[Guest]

Thanks for replys, The bike does run well,I have electronic single fire ignitionand dual plugged heads.I have tried differant timing setting via timing light.I have never had problems with pinging.But the bike does seem to kick start rather easily considering the longer stroke

[Guest]

In my last post I said kick starts easy I should have said kicks over easy
But like like I said before, the bike runs well,I just think it could run better

[rrhawg]

It sounds like your on the right tract. There is nothing like compression for building power. You might look at putting a VOES switch on also if your ignition has provisions for it. With the dual plugged heads you should be able to retard you timing about 5 degrees also.
I have a panhead running 10 3/4 to 1 compression and it runs great.
What about the head work? Flowed heads make a world of difference. Along with a free flowing exhaust. Consider it a air pump, the more air you get into and out of the cylinders the better it will run.
Rich

[Guest]

I posted once on this forum a while back I dont remember my user name or password. I cannot log in because It says me email address is invalid .the posts I reply as a guest keep being kicked out HOW can this be fixed?

[panhead]

I posted once on this forum a while back I dont remember my user name or password. I cannot log in because It says me email address is invalid .the posts I reply as a guest keep being kicked out HOW can this be fixed?

You are registered as rrennchh. I emailed you a new password.

[fourthgear]

I'm running KB pistons @ 9.5-1 and they run & start fine . My motor is stock displacement . One kick starts , warm or cold.

[Guest]

I was thinking of boring to 3.5 and using 4.250 pistons with stroker plates to dial in compression ratio

[Guest]

Ok maybe I can post as a guest I should have added stroke before 4.250 I think the plate and base gasket should add up to somthing like .125