SJ compression...?

[ags0702]

Hey everyone- Just got a squarenose the other day. Runs great put a tank of gas through it already. My question is this: The ski was set up to have 175psi of compression, I was told. I tested it after I rode yesterday and it read 180/165 F/R. I just tested it again after sitting a day and it read 180/160 F/R. Can anyone give me some insight on my issue here? What could be causing this difference? Thanks!

 

[wydopen]

try a different comp tester..

 

[demolition_x]

what brand of gauge are you using. most the cheap ones fluctuate quite a bit.


are you holding the throttle wide open as you do this with both spark plugs removed from the head?

 

[Boris]

So one day the front has better comp. than the next roles are reversed ?
Put a new shreader valve in that gauge, charge the battery an try again.

 

[chrisdoc0608]

adam, it is broke, just give me that b pipe and sell that pos :biggthumpup:

 

[ags0702]

sorry that was a typo the cylinders didnt switch psi.

Its an average tester, pretty new only used it a few times before...

Yes throttle all the way open, both plugs out.

 

[wydopen]

might need a headgasket..is the pisser from the head dirty???..like the one from the pipe??

 

[ags0702]

nope it's clean.

 

[wydopen]

nope it's clean.

try a different gauge then

 

[chrisdoc0608]

it could easily be your gauge. i know you are using the auto zone or advance auto one. they are not always the most accurate

 

[ags0702]

When I tested it with his guage there was a bit of a variance, but not as much as I am getting now.

 

[chrisdoc0608]

u used his gauge to test with the 180/165? and yours with the 180/160? if so i bet that is why... two diff gauges.

edit: never mind, you tested it yesterday so it was with yours both times..

 

[ags0702]

Now Mine's testing 180/165 yesterday, 180/160 today.
You think I should be worried aboot it?

Will it be an issue running it with a decent variance between cylinders?

 

[wydopen]

just run it...

 

[chrisdoc0608]

run it... i think i remember reading that 10% diff on the cylinders is the cutoff. but i know of ppl that ride ones that are off more than that and have no problems.

 

[ags0702]

ok...hopefully it will be alright

 

[chrisdoc0608]

i hope it blows up so i can snatch that pipe

 

[ags0702]

I hope you blow up, you part whore!

 

[#ZERO]

Ideally, there should be no more than 10 psi difference between cylinders.

If the difference is greater than 20 psi, you should consider removing the cylinder head for inspection.

If the difference is greater than 30 psi, you should consider removing the cylinder and pistons for inspection.

 

[Mouthfulloflake]

Nah.

Ive been running one for YEARS with 185 and 155.

its still plenty strong, and is the most reliable boat in my fleet.

when it STOPS running well, is when you tear into an engine.

never tear down a running engine because you are LOOKING for something wrong.

jeebus.

Ideally, there should be no more than 10 psi difference between cylinders.

If the difference is greater than 20 psi, you should consider removing the cylinder head for inspection.

If the difference is greater than 30 psi, you should consider removing the cylinder and pistons for inspection.