High compression pistons????
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Tourer
Joined: Oct 2007
Posts: 367
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From: Draper, Utah
High compression pistons????
I'm going to do some work on my 07 rg this winter, i'm looking for some high compression 103 pistons, something around 9.8 to 1, i would prefer not having to use compression release valves, also my bike has 55k on it and i am not ready to rebuild the entire motor yet so i don't want to put to much stress on the bottom end. Any suggestions or recommondations would be appreciated. Thanks
Road Warrior
Joined: Oct 2009
Posts: 1,403
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From: se michigan
cams are the key issue run the wrong ones and you'll need a better starter or compression release. Due to an unfortunate incident with a leaf spring recently(put a hole in my cases) I'm currently having my 10 SG motor rebuilt into a 103 now. My engine guy has talked me out of changing the cams(due to the starting/compression release issues among other things) and promises I'll be more than happy with the 103 and a good tune. Doing the lower end upgrade, crank welded/flywheels trued w/timken bearings while it's torn apart along with torrington cam bearings. Want this bike to be reliable more than anything as it's my touring bike not a street racer/bar hopper.
Tourer
Joined: Aug 2010
Posts: 320
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From: Hudson Valley
Here's the way I see it although, its just my opinion fwiw.
Decide your riding style.
Pick the cam that best suits your riding style.
Build your motor around that.
And flhxkiller, maybe for your riding style, the stock cam is best. It is certainly an EPA compromise, but it could be the right cam for you.
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Tourer
Joined: Oct 2007
Posts: 367
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From: Draper, Utah
[QUOTE=inverse121;7231221]Tell us what cam you are gonna run? The cam will bleed off some compression. You need to know your cranking pressure to determine if you need compression releases or a high torque starter. I have SE255's in there now, I was planning on keeping them. your thoughts
Road Master
Joined: May 2008
Posts: 1,196
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From: connecticut
I'm going to do some work on my 07 rg this winter, i'm looking for some high compression 103 pistons, something around 9.8 to 1, i would prefer not having to use compression release valves, also my bike has 55k on it and i am not ready to rebuild the entire motor yet so i don't want to put to much stress on the bottom end. Any suggestions or recommondations would be appreciated. Thanks
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Ultimate HDF Member
Joined: Feb 2006
Posts: 5,939
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From: TX
S/E flattop pistons & 103 kit will get you where you think you wanna be (9.8 ~ 10:1 static CR).
I can ASSure you, you do NOT want high compression pistons in that setup, with SE255 cams. Hot only with the cylinder pressure be "through the roof", you will have exceeded the CR best suited for that cam.
As SPOracer noted, there are many superior alternatives. He has one of them on his scoot.
I can ASSure you, you do NOT want high compression pistons in that setup, with SE255 cams. Hot only with the cylinder pressure be "through the roof", you will have exceeded the CR best suited for that cam.
As SPOracer noted, there are many superior alternatives. He has one of them on his scoot.
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Tourer
Joined: Aug 2010
Posts: 320
Likes: 24
From: Hudson Valley
255s are not the right cams for high compression, sporacer and PhilM said it well above.
Read FuelMotos thread on the T6-6 and TW-555
I've never run a Tman cam, but I like TR.
And may be looking at one for my next build.
Read FuelMotos thread on the T6-6 and TW-555
I've never run a Tman cam, but I like TR.
And may be looking at one for my next build.
Last edited by inverse121; Sep 2, 2010 at 10:06 PM.
Road Warrior
Joined: Oct 2009
Posts: 1,403
Likes: 25
From: se michigan
was considering running the SE255 cam originally, the other issue is that I ride in areas of the country that have shitty gas(ie low octane/ethanol blend) on a regular basis and that the torque type of cam doesn't care for that type of fuel. I'm looking for a good running bike that will run on any type of fuel in a pinch w/reliablity being first and foremost on this bike.