Cross Piston vs Meteor

[Jimmy in NC]

Have a Stihl 066 here and bought a Cross top end kit. Stuck it together with new seals and rubber bits. Bearings are fine. Fired it up with a glued down jug and man do I like this saw. (I like it more than any other 66 I have run to date and I've run a bunch.)

Next day I am telling a good friend how I like that kit and he gets quiet...and says take it off and put a Meteor in it. OK....he insists and I purchase a Meteor.

I pop the top and find a film of aluminum dust is mixed in the oil coating. I immediately look for a source...all I could see was scuffing on the piston skirt. I took a few minutes and deburred the ports more by hand to make sure... and then finally unboxed the Meteor. What I noticed is the Meteor fits better in the bore.

Obviously Meteor is going in there... but any other places to check before I put it back together again? Could this piston slop be why so many of these Cross pistons fail?


Rings had .008" end gap and were Caber.

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[Jimmy in NC]

I put a touch of starting fluid on the piston crown and you can see how the aluminum floated to the edge.

The other picture shows the ring spacing difference with Cross on Left and Meteor on Right.

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[Warped5]

Nice video, Jimmy .... good with my coffee!

 

[Jimmy in NC]

Morning Ted. Im curious on these piston and I hope the piston skirt is where all the aluminum powder came from. We will see....

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[huskyboy]

The meteor looks to have less casting flash/better fit/finish just looking at your pictures.

 

[Loanstar]

In my line of work, autobody repair and restoration. I totally understand the difference between aftermarket, oem replacement and genuine oem. Preparation is the key to making said parts work for vehicles. So i have to ask... Did you wash the cross piston before installation?

 

[Jimmy in NC]

In my line of work, autobody repair and restoration. I totally understand the difference between aftermarket, oem replacement and genuine oem. Preparation is the key to making said parts work for vehicles. So i have to ask... Did you wash the cross piston before installation?

Yes. They always get a bath before final assembly.

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[Loanstar]

Sorry,was only checking. Sounds like you did everything right and the parts fitment is the issue.

 

[Onan18]

Put the cylinder on a lathe and check the base to make sure it is perpendicular to the bore.

 

[MustangMike]

I'd like to hear from anyone else who either has, or has not, been having troubles with the Cross Pistons, as I have put several of these together.

I pulled my Flying Tiger apart after about 10 tanks (most of it milling) because the Huztl piston pin bearing was beginning to fail, but I thought the P+C still looked good.

I have also heard the squish band may need to be adjusted when going to a Meteor piston.

Anyone else with comments???

And yes, I do like how the Cross P+Cs run, and I always make sure I check the bevel on the cylinder ports.

 

[RIDE-RED 350r]

I'm curious to see some comparative measurements between both pistons. Obviously there is a size difference, but what I'm wondering is how much size difference translates to what you have experienced here

 

[huskyboy]

There’s a reason why oem cylinders have A,AB,C markings on top and matching piston. How much does it matter? I don’t know, I’m not an engineer. Does the cross have those markings and matching piston?

 

[Jimmy in NC]

I'm curious to see some comparative measurements between both pistons. Obviously there is a size difference, but what I'm wondering is how much size difference translates to what you have experienced here

Ill measure better later today. I know the internal bosses are not nearly as nice as the Meteor and a friend pointed out it would cause the rod to walk and lead to crank failure in short order. I have no scale and only cheap calipers but I will see what I can kick up.



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[Time's Standing Stihl]

Great video Jimmy.

@huskihl take a look

 

[Basher]

You only need feeler gauges Jimmy, cram as tight a feeler gauge between the piston skirt and cylinder wall to tell how much clearance there is between them. Any more than .003 on a new one and that piston is useless, From the drop rate I think you will find in excess of .003. A new piston should be .001 to .0015 for a good tight running engine.

 

[RIDE-RED 350r]

Ill measure better later today. I know the internal bosses are not nearly as nice as the Meteor and a friend pointed out it would cause the rod to walk and lead to crank failure in short order. I have no scale and only cheap calipers but I will see what I can kick up.



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As long as you can read thousandths with your caliper you can get good comparative measurements

 

[angelo c]

You only need feeler gauges Jimmy, cram as tight a feeler gauge between the piston skirt and cylinder wall to tell how much clearance there is between them. Any more than .003 on a new one and that piston is useless, From the drop rate I think you will find in excess of .003. A new piston should be .001 to .0015 for a good tight running engine.

Are these cyls "choked" ?
Where do you measure in the stroke ?

 

[smokey7]

Ate these cyls "choked" ?
Where do you measure in the stroke ?

I usually measure at tdc middle and bdc.

 

[blsnelling]

That Cross casting looks pretty nasty. I recommend you don't use those circlips.

 

[Jimmy in NC]

That Cross casting looks pretty nasty. I recommend you don't use those circlips.

That whole assembly is a paper weight. Meteor is going in. I've been through the jug and found some spots below the exhaust I don't like but with some polishing they will run. I have also gone back through the bevels by hand. Rewashed jug and it is drying. Itll go back together and we will see how she does. The saw makes great power but I doubt it'll make a ton of hours.

Cross piston has a clearance of .003" maybe more. The Meteor is .001". Meteor it is.

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