compression tester question

[axlracing]

hey i just bought a compression tester and want to see how accurate it is. One way i can tell is i have a polaris predator 500 that i just put a 11:1 je piston in any idea of how much 11:1 = in pounds. I checked my banshee and is says 110 pounds i am wondering if its off or if i am really that low thanks axl

[sinisterboo]

you can buy 9 different brands and guess what, your gonna get 9 different readings. I bought one from mac tools, and whether its right or not, its still the only one i use, just so i know theres no variation.

[axlracing]

if i knew what this je 11:1 piston = in pounds then i could check the predator and see how far its off?

[jbooker82]

you cant say 11-1=psi. Bore size and duration of intake and exhaust greatly affect the pressure readind. Stock Banshee has around 6-1 compression ratio if I remember correctly. What mods an elevation are you at?

[Banshee0028]

you can buy 9 different brands and guess what, your gonna get 9 different readings. I bought one from mac tools, and whether its right or not, its still the only one i use, just so i know theres no variation.

How much did you pay for your mac tester? I bought a $50-$60 craftsman tester and I think its accurate but my comp seems too high >200

 

Jeff told me to try to borrow a snap-on or similar but I dont know anyone with one. There is a MAC dealer down the street from me I am going to try to talk to as soon as I see him next...But I dont know if mine can be off that much in each cylinder>?>

[Snopczynski]

I have a mac tester, a matco tester, a KD tester, and a craftsman tester. I had the mac tested/certified and it is the only one I have thats within 3 psi of the actual reading.

[Banshee0028]

I have a mac tester, a matco tester, a KD tester, and a craftsman tester. I had the mac tested/certified and it is the only one I have thats within 3 psi of the actual reading.

Snop, can you tell me about how much off the craftsman tester is compared to the mac? This might help me figure out how much mine is off .... Although I know this is not a perfect comparison since its 2 different testers.

[Snopczynski]

I thought it was around 25-30 psi.

[Screaming Yellow Zonker]

there is no real way to say what an 11:1 engine could have for pressure. like said above pressure is effected by everything. If your bike has 200psi in each cylinder than your leg should be sore after kicking that monster over a few times. Also if it does have 200psi in each you need to let me know who your builder is. That has to have some good power...

[monster_energy06]

i just got one today 30$ at candian tire and my shee with stock bore wiseco pro lite pc pipes and pod filters .got around 125 psi each side cold engine w/o throttle.. thats about were it should be from what ive seen

Edited April 26, 2008 by monster_energy06

[Banshee0028]

I thought it was around 25-30 psi.

 

I think it might be off my 30 lbs or so...But to be at 210+ for a woods port and 20cc domes!?!?!

 

there is no real way to say what an 11:1 engine could have for pressure. like said above pressure is effected by everything. If your bike has 200psi in each cylinder than your leg should be sore after kicking that monster over a few times. Also if it does have 200psi in each you need to let me know who your builder is. That has to have some good power...

 

Kicking it over does not feel hard at all, in fact it feels about the same as when I tested it before my rebuild when it tested at 160lbs psi. I think its about 160ish....I will test again soon and see if its different.

[Snopczynski]

was it resleeved with the exaust ports lowered? Or are you running some weird pistons in it?

[Banshee0028]

was it resleeved with the exaust ports lowered? Or are you running some weird pistons in it?

795 series, 4mill port matched, woods port, 20cc cut domes.