Cross Performance 660 top end failure

[Wagnerwerks]

That is rough. Will you tear it down and split the cases for repair?
Isn't there a chance that left over stuff from the piston is in the bottom of the case?
Just thinking out loud.

That's the worst part of mechanical failures..... You only have one way to know for sure.......

 

[Brewz]

I wonder if it may be a piston problem.
If I recall correctly, my cross pistons measured .003" less in diameter than the farmertec.

I am thinking this too.
The cylinder aint that bad, It looked fine which is why I just bolted it on stock.
Im wondering if there are inconsistencies in the piston ring grooves or casting quality and they cant handle the added load of the hard Cabers pulling up on the ports?

Its a shame because the port timings are very nice.

I have a Hyway top end here and its got better casting and plating quality but port timing is not as good with about 30* blowdown

 

[Bluefish]

Wow, that stinks, I thought these were endorsed more or less by some reputable saw guys on here. I might have read wrong but I thought they were sporty. Tough break, sorry it happened...
Russ

 

[Adirondackstihl]

Let me know when they fixem.
I got a roached 660 needing a top end

 

[Gentleman]

No consistency in these damn parts. One is good....the next is bad.....etc.

Have you talked to @Gentleman ?

We'll send a replacement today

 

[Keith Gandy]

Hi Folks.
I noticed one of the boys doing the Chinese 660 clone saws had an issue with a hung ring on one of these top end kits.

I have had one here for a little while now and put it on a saw I rebuilt for a friend.
It started fine at first, let it warm up, tuned the idle and rough adjusted the carb to be 4 stroking strong and shut it down to be field tuned and tested in some timber.

I got it out in the field and tried to start it, it popped 2nd pull but the pop was very short.
flicked it up to run position and cranked it over a few times and nothing, wouldn't start.
Went to try it without the decomp but found the decomp was already closed.
The saw suddenly had no compression.
Took it home and checked the decomp and spark plugs, both fine.
Took the muffler off and it was full of metal.
It has hung the ring on the exhaust floor and destroyed the piston and cylinder.

Not happy!

It was completely stock, as the kit came out of the box, with gasket installed.
Wasn't cheap with post and exchange to Australia either.

I am wondering if anyone else has experienced one of these failures?

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Whoa!! Sorry man , thats a ugly mishap!

 

[Mastermind]

Wow, that stinks, I thought these were endorsed more or less by some reputable saw guys on here. I might have read wrong but I thought they were sporty. Tough break, sorry it happened...
Russ

I did the prototype, and that's why the port timing is better than most other AM top ends. Sadly, the manufacturer has not got a stringent QC department.

At least Bruce is top notch about making good on defective units.

Let me know when they fixem.
I got a roached 660 needing a top end

Every one I've seen has been very nice. But, once in awhile one fails.

 

[Mastermind]

I am thinking this too.
The cylinder aint that bad, It looked fine which is why I just bolted it on stock.
Im wondering if there are inconsistencies in the piston ring grooves or casting quality and they cant handle the added load of the hard Cabers pulling up on the ports?

Its a shame because the port timings are very nice.

I have a Hyway top end here and its got better casting and plating quality but port timing is not as good with about 30* blowdown

I really wish these manufacturers would step up on QC. We have a chance to get started making parts with some control over the specs, but without consistency it's a lost cause.

 

[fordf150]

It's Chinese so failures and modifying it to avoid failure is kinda expected. If they are given the choice between producing 1000 shoddy units a day or 500 perfect units they will always choose the 1000 shoddy ones unless a manufacturer is standing over them to insure the quality is consistent.

Thats the reason companies like stihl and makita own the plants vs just farming out the work to a low bidder.

 

[MrWhoopee]

Now you've got me worried. How, exactly, does one chamfer the ports? I have a right-angle die grinder, but it's too big to fit inside the cylinder. I also have a Rout-a-Burr, but I'm worried it would chip the Nik-a-sil. Please explain.

 

[wcorey]

Now you've got me worried. How, exactly, does one chamfer the ports? I have a right-angle die grinder, but it's too big to fit inside the cylinder. I also have a Rout-a-Burr, but I'm worried it would chip the Nik-a-sil. Please explain.

You don't need a rt angle, a dremel or flex shaft with a straight handpiece is fine. Use a relatively fine abrasive ball (or similarly radiused),
the diamond ones work well and can be fairly inexpensive. Size isn't that critical but I've found bigger (to a degree) is easier to get consistent results.
Just go around the edge of the port (top/bottom mostly, sides not really needed), idealy so the chamfer is only slightly tipped in toward the inside, not equal like a 45.
Finish with a strip of sandpaper on your fingertip, 320 or so grit should be fine...

 

[kkemp]

The one I have looks really good . I haven't run it yet though .

 

[wcorey]

You'd think these would be hanging on the roof if anything, it being so flat.
Odd...
Would seem to point toward the piston, with the weaker direction being on top of the rings.

 

[blsnelling]

I'm not a fan of those super stiff Caber FCast rings either.

 

[JonCraig]

Can you tell by the ring itself if Cabers are f cast? Or only the packaging?

 

[kingOFgEEEks]

What are advantages / disadvantages to having a harder of softer ring? Harder would last longer but more prone to hanging?

 

[fordf150]

Can you tell by the ring itself if Cabers are f cast? Or only the packaging?

dont know if they are all like this but the ones i have here at the shop are as follows:

F-Cast= dark in color and rough texture(almost like a glass beaded piece of metal)

standard=shiny and smooth

 

[jb-chainsaws]

has anyone had any bad experiences with the 084 cross top end? I only ask as I've just bought an 084 that has one installed, tempted to pull the jug and check there bevels

 

[Chainsaw Jim]

The chamfer or bevel at the port only matters on the plating. Fine sandpaper by hand works well. Grinding shouldn't be necessary and will run the risk of chipping off chunks of plating.

 

[MrWhoopee]

You don't need a rt angle, a dremel or flex shaft with a straight handpiece is fine. Use a relatively fine abrasive ball (or similarly radiused),
the diamond ones work well and can be fairly inexpensive. Size isn't that critical but I've found bigger (to a degree) is easier to get consistent results.
Just go around the edge of the port (top/bottom mostly, sides not really needed), idealy so the chamfer is only slightly tipped in toward the inside, not equal like a 45.
Finish with a strip of sandpaper on your fingertip, 320 or so grit should be fine...

Thanks, that makes it clear.