Super Jet 701 62t blown o-ring (brainsrtorm)

[Wakoski]

Greetings
while i try to work my way through the problem and research the forum I am coming up short. I have a 701 62t which I blew the rear cylinder head o-ring on... The o-rings had some obvious wear and age to them so I replaced all of the o-rings and gaskets in the head. A bit of wishful thinking that this would resolve my problem. Obviously there is a main cause to why the o-ring blew because after cleaning and changing all the o-rings it didn't fix it. The compression on the front is 160 and the rear is 120. It has a riva head fyi. When it blew there was water shooting out of the rear of the motor/head, around the same location where the o-ring failed.

Any ideas as to where to check/test next would be much appreciated. Or if there is any additional information that would be helpful to troubleshoot the problem please inquire.

Thank you!

 

[Vumad]

Install using grease so the o-ring stays in it's proper place while you install it.

 

[Wakoski]

I applied that technique and still have the issue. I will remove the head and inspect the components to verify it is all good. thank you for your reply.

 

[OCD Solutions]

X2, if you did a thorough inspection before you reassembled and found nothing that would explain the drop in compression, then I would say that you pinched an o-ring when you reinstalled. (Greasing helps but is still not 100% foolproof).

O-rings can just fail over time but another thing to check is if the sleeve dropped in the cylinder; the top of the sleeve should be perfectly flush with the top of the cylinder.

 

[taylor2000]

i used indian head gasket stuff that is sticky stuff that is in the brown bottle to hold it in place while installing head. also stretched the oring abit when wrapping it around the last little bit and cut off the extra. i cut it where it over lapped the start of the oring just so when it found its true spot it would shrink and leave a empty place of no oring. just my way. i havent had issues.. could hid head be warped?

 

[SJ 701X]

The o ring around the dome sealing off the piston or the o-ring sealing off the water jacket?

 

[Wakoski]

it is the o-ring that is on the bottom side of the head and makes contact with the piston sleeve.

 

[Wakoski]

I removed the head and inspected the o-rings and orangish gasket material, all looks good. Checked compression and still have 160 front and 120 rear... @OCD Solutions: I am not completely clear as to the "sleeve" but everything with the piston and the jug seem to be matched up. Any suggestions how to proceed?

 

[jo5hi3]

stock head or aftermarket....cause if your using a gasket with an oring head that may be your problem

 

[iangdesign]

Your head or cylinders may be warped. Lay the head down on a flat surface, grab a metal ruler or something with a known straight edge and place a flashlight behind it. If you see any light coming through where it should be straight, it's warped.

Maybe compression in the rear cylinder being that low you may need a re-ring on the piston and bore on the cylinder.

 

[Wakoski]

It is a Riva head and it has o-rings and by gasket I meant a thin rubber material that is seated around the perimeter.

 

[jo5hi3]

if its going around the outside of the head then that is just for keeping water in the cylinder, they dont have anything to do with compression, if your talking about the orings that go around the top of the sleeves thats a different story

 

[Wakoski]

the o-ring that blew was around the cyclinder, on the bottom side of the head against the cylinder jug.

 

[JetManiac]

As others said, you most likely have a dropped sleeve or warped out of true head or cylinder top.

 

[Wakoski]

@jetmaniac what would be your suggestion as how to proceed? Or how to diagnose what may be wrong and what is good? thank you.

 

[wanderer1]

Is the Riva head a 2 piece shell with removable domes? If so are the domes tight or are they rattling. If the dome seat area has come out of torlerance from wear then the dome can vibrate and wipe out the o-Ring. Just a thought good luck

 

[BrapCap Moto]

I'm having an o ring issue as well i just blew my second compression oring on an ADA head in only 2 Hrs. Im debating a faulty install, but then again my cylinder sleeve is flush all the way around except for a 1-1/2" spot it is actually raised almost the thickness of a piece of computer paper. What can be done in this situation? Should i even be concerned? can cylinders be milled?