Compression ratio

[SLEEPERBUSA]

I am probably going with the Wossner 1441cc,  13.5:1 pistons.
I would really like it if I could get atleast 14:1.
How much would I gain by leaving out the base gasket?
Any suggestions are appreciated.

Thanks

[sportbikeryder]

You can;t jsut "leave out the base gasket". You will need to measure the deck clearance first, along with your piston to valve clearance, provided you have a fairly high lift cam. Then you can set the deck and look into getting more removed from your head or block when you have it surfaced if you want a smaller combustion chamber.


Removing more material from the block will change the piston to head as well as teh piston to valve clearance. Removing more material from teh head will not change piston to head, but will change piston to valve. 

[SLEEPERBUSA]

Got ya. Thanks.
I'll be going with Carpenter head and cams. Would it be a good idea to send him the cylinder and pistons too, so he can set it up the way he wants it?

[sportbikeryder]

Got ya. Thanks.
I'll be going with Carpenter head and cams. Would it be a good idea to send him the cylinder and pistons too, so he can set it up the way he wants it?

It really needs to be done with everythng (cases, crank, rods, pistons, cylinder, head in order to be sure it is right for your application. Otherwise it is really jsut a guess and you shoudl err on the loose side to avoid issues.

[SLEEPERBUSA]

Thanks for the good info.
 

[glenn71]

Remember,the bigger you go with the cams.the higher you have to dial them in to get sufficient piston to valve clearances which then locks you in to a mostly top end hp motor,unless you start machining the valve reliefs in the pistons.

[SLEEPERBUSA]

 

[GRUNTMAX]

Spot the 4 bent valves. Not enough clearance
Ran real good for 20miles though

[Pat Dietrich]

Sleeper- I took .020 off my head and I have 14:1 . Please don't  tell anyone. Its a secret

[SLEEPERBUSA]

I'm good for a secret!

 

[glenn71]

i found adding compression really improves
part throttle torque quite noticeably and makes the cams
kick in sooner.i ran 13.8:1 on pump
98ron with slight pinging around 3500
which i sorted with timing.i ran 13.45:1
on 98 and only a bit pingy around 2000
on heavy throttle,otherwise fine.on your
93 fuel which is equivalent id pull 4-6 degrees
timing out of it everywhere before you run it
and work forwards from there on a dyno with a knock
detector.it only takes one bad batch of fuel
and it will spin a bearing,kill a rod,crank,piston,etc.
you could set up a limp map with a map switch to get you home
with much less timing and lots more fuel as a safeguard.

[wildphil69]

gen 2 valves raise compression around .1 i have a set with 110 miles on them 

[GRUNTMAX]

i found adding compression really improves
part throttle torque quite noticeably and makes the cams
kick in sooner.i ran 13.8:1 on pump
98ron with slight pinging around 3500
which i sorted with timing.i ran 13.45:1
on 98 and only a bit pingy around 2000
on heavy throttle,otherwise fine.on your
93 fuel which is equivalent id pull 4-6 degrees
timing out of it everywhere before you run it
and work forwards from there on a dyno with a knock
detector.it only takes one bad batch of fuel
and it will spin a bearing,kill a rod,crank,piston,etc.
you could set up a limp map with a map switch to get you home
with much less timing and lots more fuel as a safeguard.

....n waiting on parts.
13:1s will be set up @ 12.5:1.
Not much good fuel in some places. I should have enough in the top end with the gearbox n sprocket job. Cooler running up top. cheaper fuel too.....& more valve clearance when your not going for top end grunt with high cam lobe centers.