Any logical explanation as to what this is?

[Danj56]

Originally Posted by risk74

The bottom part of the cylinder that supports the intake side of the piston appears to be broken off as well.

Definitely looks like a chuck is missing off the bottom of it.

[Zephyr]

Anyone familiar with these cylinders know how much is missing? Hoping it's not too much and I can just clean the edges up and have it replated.

Also, good bit of play on the rod left and right, but surprisingly no vertical movement. The crank does seem a good bit tighter to the right side case(clutch cover side) than the left. Is this a normal thing?

I haven't found any large debris yet, but lots of small chunks missing and gouiging here and there. Pretty bad on the right side of the case next to the crank. I'm pretty surprised how tough this motor is, after ingesting such things and not locking up. Upon closer inspection it looks as if there were two pieces of something glued in between the two aluminum pieces, and they're nowhere to be found so far.

[Zephyr]

Here's a better shot of the bottom rear area of the cylinder. Also, while rotating the power valve by hand, seems like it turns a good bit on one side(1/4 turn or so) before the other side catches on and begins rotating and the valve actually begins lifting. Hoping it's just something loose in there, as it's binding a bit sometimes as well.

[hadfield4wd]

What do the cylinder walls look like?

Its odd that there are no pieces in there. How is the powervalve?

I'd say you at least need a piston and if you're going to split the cases, which you should I believe, then do a rod at the same time. Piece of mind is priceless.

[Wimpy525]

I send the cylinder out to Power Seal, you would be surprised what they can fix.
I'd clean out the bottom end as the part that broke went somewhere.

[Zephyr]

Cylinder walls have a good bit of vertical wear marks, no serious damage that I can see so far. Typical wear pattern with a few odd ones here and there. I'm planning on dropping it off at Powerseal in PA, once I get a new piston. I'll try to get a decent picture up. I'm sure there's plenty of little gremlins to be found hiding under the crank.

I'm definitely going to get a fresh rotating assembly in there(crank, rod, piston), as well as new bearings and seals throughout. Not a fan of throwing things together and crossing my fingers. Currently trying to get a list together of what I'll need before I split the cases. Fortunately I have quite a few reputable bearing suppliers by me. I've read on here that apparently some models have a 2 piece bearing assembly on one side of the crank, whereas others don't. Anyone know if these are interchangeable?

[Jim Cook]

Originally Posted by Zephyr

Cylinder walls have a good bit of vertical wear marks, no serious damage that I can see so far. Typical wear pattern with a few odd ones here and there. I'm planning on dropping it off at Powerseal in PA, once I get a new piston. I'll try to get a decent picture up. I'm sure there's plenty of little gremlins to be found hiding under the crank.

I'm definitely going to get a fresh rotating assembly in there(crank, rod, piston), as well as new bearings and seals throughout. Not a fan of throwing things together and crossing my fingers. Currently trying to get a list together of what I'll need before I split the cases. Fortunately I have quite a few reputable bearing suppliers by me. I've read on here that apparently some models have a 2 piece bearing assembly on one side of the crank, whereas others don't. Anyone know if these are interchangeable?

A parts book will help answer your questions. Many of the bearing spec numbers are shown. If you do not have one, and are having trouble downloading one, message me and I will email one to you in the pdf format.
Check here first:
http://gasgas.com/us/manuals/downloa...list1.pdf.html

I tried to attach a workshop manual to this reply, but it didn't work due to file size. Message me with your email and I will send you one in a pdf format.

Good Riding and Wrenching!
Jim

[sam097]

Im not sure about Athena gaskets but the Cometic set I bought SUCKS. The case gasket doesn't line up worth a hoot and is on the verge of not even contacting the mating surfaces in 2 places. Several bolt holes needed trimmed so the hole would line up. I could've done a better job with gasket paper and a pencil. Next time I will be at the dealer buying OEM.

[Jim Cook]

Originally Posted by sam097

Im not sure about Athena gaskets but the Cometic set I bought SUCKS. The case gasket doesn't line up worth a hoot and is on the verge of not even contacting the mating surfaces in 2 places. Several bolt holes needed trimmed so the hole would line up. I could've done a better job with gasket paper and a pencil. Next time I will be at the dealer buying OEM.

I can't say about the Cometic gaskets for GasGas, but as GasGasman says, the Athena gaskets are good, and fit exactly. I use them often.
The only thing to watch about the Athena gaskets is that the base gaskets are a different color from the OEM base gaskets. Measure which base gasket you use to make sure that you are using the one you want.

[Zephyr]

Many thanks for the input, I'm chalking it up as one for the mystery van. Parts inbound for a rebuild. I'd certainly be doing things the hard(er) way if it weren't for some of the very helpful and knowledgable members of this site.