550xp popup piston

[kårekloak]

Have just bought a AM 550xp popup-piston from Lil Red Barn. I was told the quality should be good, but with a closer inspection, I doubt they are OEM quality. The Strato ports in the new piston is not as deep as on the OEM piston, Here are some pics.

Anyone tried them?

 

[huskihl]

The top port is just weight reduction. The strato air flows through the bottom cutout.

I doubt it’s oem quality, but that doesn’t mean it won’t work either. I’d use a better ring than what came with it

 

[Stump Shot]

Of other LRB examples I have seen, the pins are not to spec, being a tad small in diameter.
If I'm reduced to using one of these pistons I replace all the hardware that comes with it, rings, pin, and pin keepers.
I believe Meteor offers a 550 piston, would be a much safer bet in quality. I put one in a previously ported saw to repair it and had no issues that I can recall.

Edit: Wasn't a pop up though, just a standard replacement.

 

[Stevetheboatguy]

Watch the underside of the piston. It may make contact with the counter weights of the crank at the bottom of the stroke.



Steven

 

[drf256]

The strato design adds a whole notha’ level of complexity to slugs. More than just opening points off the crown, you’ve got the rib over the pin (which appears to be a different thickness) that opens the uppers into the strato port to pull air into the case from the uppers.

Many more measurements than standard pistons to worry about. Who knows, could run better than stock, but I generally don’t trust any AM pistons with the exception of meteor.

 

[Ketchup]

@drf256 nailed it. That LRB piston looks like it will have a shorter strato duration. Typically more duration is what you want (though I don’t know on a 550).

x3 on the other hardware. Especially circlips. I’ve seen several AM circlips crater a saw. I would run the original wrist pin and get new OEM clips and ring (or caber).

FWIW, some believe the alloy the piston is made from is different in AM parts which may affect weight, durability, transfer and heat distribution. Most Husky pistons do seem to have their own unique color.

I can’t see in your photos, but check the gap where the con rod fits over the wrist bearing up inside the piston. Many low quality pistons will have an irregular casting where the piston rotates around the con rod. It looks like the OEM piston is machined there for a smooth surface and precise dimension (I like that).

Despite all the lower quality issues, more compression usually improves performance. I would run it with good hardware and find out.

 

[kårekloak]

A problem is that the ring is actually thicker, so I can't use oem ring as there will be too much gap in the groove. I suppose meteor/caber has oem thickness also. Despite popup and higher compression, this want me to use oem piston instead..

 

[Maintenance Chief]

The McCulloch crowd has been unimpressed with the LRB pistons, their casting looks awful and the piston pin is unusable with the pistons.
Even after the defects were brought to their attention they made no changes.

 

[P.M.P.]

The McCulloch crowd has been unimpressed with the LRB pistons, their casting looks awful and the piston pin is unusable with the pistons.
Even after the defects were brought to their attention they made no changes.

This is really sad was thinking on ordering one.

 

[Maintenance Chief]

This is really sad was thinking on ordering one.

Yeah, if you press in original pin bearings and use the original pin it'll stay put, but even with that the skirts hit the crank throws ? Its like they copied it from a 3rd grader's drawing of a picture.

 

[Nutball]

Probably Golf pistons right? The Golf piston I've seen is super thick and heavy compared to OEM.

 

[kårekloak]

This is sad to hear. I contacted them before i ordered to hear about the piston quality. I was told a local company makes the pistons which also supply oem parts to manufacturers in Europe. The pistons was designed by a pro chainsaw builder in pensylvania..? Overall I don't think the quality is even close to OEM.

 

[cuinrearview]

The pistons was designed by a pro chainsaw builder in pensylvania..?

 

[timg]

Hey now Tim, He's a New Yorker. No disrespect meant to my Northern neighbors, Just old Ironhorsie!!

 

[cuinrearview]

Hey now Tim, He's a New Yorker. No disrespect meant to my Northern neighbors, Just old Ironhorsie!!

NY, PA, same thing

 

[timg]

MEH

 

[broadwayline]

Damn, ordered a spare 242 piston from LRB as a backup - kinda bummed lol

 

[kårekloak]

I have now grinded and widened the piston stratos ports to be like the oem one. Not sure what the upper port actually does, but the one on the oem piston was way bigger and deeper. I have also beveled 45degrees on piston skirt.

 

[kårekloak]

Here you can see the ring groove is thicker than on the oem piston, so I can't use caber/oem rings.. After removing material, it is also a tad lighter than the oem piston, 7 grams (0.25oz) ?

 

[huskihl]

Not sure what the upper port actually does, but the port on the oem piston was way bigger.

2nd post

The top port is just weight reduction. The strato air flows through the bottom cutout.