[shawn169]

Hi
anyone know what the compression should be? 08 700XX

thanks
Shawn & Kyle

 

[Baxter]

Last time I tested mine it was around 100psi. That was just putting the clock on and using starter switch.

 

[M_Quick]

section 9:6 in manual says 65 psi, do you have the service manual Shawn169? You will find link here, if you dont allready have it...

http://www.club700xx.com/vb/showthread.php?t=2195&highlight=service+manual+trx700xx

 

[shawn169]

hi M Quick
I do have the service manual and yes I saw that where it says 65psi.. but that seems way to low.
there must be a decompressioner of some sort.
the bike seems to be having problems.
It can use 1/2l of oil for an 80k run
most times when starting cold it can be a real bitch. It will back fire in the air box and the exhaust.then It most times will start but today it wouldn't start.
the bike was used hard before we got it so god knows what was done wrong.
is there a way to check the fuel injection?

any ideas guys?

Thanks

 

[xx700xx]

65 does seem low, hmmmm. My snowmobile was 120 across the board last season. Totally different application but you would think the atv would be in that ball park.

 

[M_Quick]

[FONT=Swiss721SWA,Bold][FONT=Swiss721SWA,Bold]

As far as the compression being low, Idk maybe one of the engine builders can chime in. The manual says 65lbs, so I'd say if its atleast that its ok. Now I see why it seams low, heres a paste from my 2004 Polaris Predator 50/90cc Sportsman 90cc manual. And note compression is higher in the 50cc unit?


Cylinder Compression: 0--1000 ft (0--300m)
50 cc models: 110--130 psi​

90 cc models: 90--110 psi
[/FONT][/FONT]

 

[shawn169]

when I did a compression test I was geting around 80 so it seems good like that.the bike doesn't smoke , i would think it would be with it using that much oil. We did a fresh oil and filter change I'm hoping this may help.

 

[M_Quick]

Idk but if it's using oil, I'd say it has to either be burning it or leaking. So maybe replace the washers on the drain plugs too?

 

[maxxv123]

The backfiring into the intake/airbox would indicate that the intake valves were not closing all of the way, so the combustion was escaping in that direction. I would check the tappet clearance - if the clearance is too small, the intake valve(s) could be hanging open slightly, which could be causing the lower value on your compression check. Make sure you are at Top Dead Center when adjusting.

As far as the oil consumption, it could be leaking out of one of the drain bolts, so check the sealing surface for anything wierd like debris, and try changing crush washers. If its not leaking out of a drain bolt, then it must be burning - meaning that the oil is coming past the piston rings or valve stem seals.