How to install piston in clamshell engine (ms290)? help!

[brages]

OK...

I have done this once, but I'd like a refresher before I break any more rings. :censored:

Are there any good threads discussing how to put the piston into a clamshell like the ms290? Pics? My ring compressor is no good for a clamshell, my hands don't seem to be able to do it by themselves. I think I used part of a 2-liter bottle last time... any good tips? I think there's a way with a zip tie -- that sounds smart...

 

[ckelp]

with me they have always just went in without a ring compressor
but, i've never installed new rings

 

[JDNicol]

Although time cosuming, with my 039 (and all clamshells) i removed the clutch, flywheel etc such that the whole engine was outside the tank housing. Installed new piston etc. Then lube the piston and rings up, invert the cylinder and slide it in. Doing it this way you are able to see exactly whats happening and be able to properly align the piston with the cylinder. You shouldn't need a ring compressor as the sides of the cylinder compress the rings but i find a tooth pick can come in handy sometimes. Then reassemble.

 

[brages]

Yeah, that's pretty much what I was doing... I already have the cyl. out.

 

[blsnelling]

Easy peasy Allign the rings with the locating pins. Set the piston into the bottom of the jug. Start the rings down into the bore, starting with the side where the locating pin is. Use a small carb adjusting screwdriver to carefully push the ring into the groove. Work your way around the bore. Once the first ring is in, do the second one the same way. The rings should go into the bore very easily like this. The bore is tapered at the base, so all you really have to do is get the rings started into this taper, making sure the ends are in the proper location. If you broke a ring, just use more finesse next time. Easy does it.

 

[brages]

I had actually grabbed a little screwdriver for getting the rings in, but I was thinking, "This has gotta be the wrong way to do this!"

 

[blsnelling]

I had actually grabbed a little screwdriver for getting the rings in, but I was thinking, "This has gotta be the wrong way to do this!"

It probably is wrong, lol. I'm sure Stihl makes a specific ring compressor just for this job. But there's more than one way to skin a cat.

 

[oscar4883]

The ring compressor Stihls sells is cheap enough but the carb screwdriver method like Brad talks about works well enough. Just need a gentle touch is all. Its not a complete nightmare like others have made it out to be.

 

[blsnelling]

It's actually very easy to get the rings in. Just start with the ring ends, and then work your way around. You'll probably only have to give a little push on the two transfer sides. It should slip right in. I assume your lightly lubing the piston/rings and cylinder first?

 

[Saw Dr.]

Here is one I did.

http://www.arboristsite.com/showpost.php?p=2315642&postcount=35

 

[brages]

Thanks!

(I guess I need to spread some rep around -- I can't rep the people who are always helping me!)

 

[pioneerguy600]

If anyone is afraid of scratching the piston with a screwdriver just use a wooden popsicle stick/ I have a dispenser of them filled with sticks, they came off a lunch vendors truck where they were used as coffee stir sticks, I find a lot of uses for them in the shop.

Pioneerguy600

 

[Rickochet]

The small carb adjusting screwdriver I use is made of plastic eliminating the chance to damage a ring or piston.

 

[andrethegiant70]

If anyone is afraid of scratching the piston with a screwdriver just use a wooden popsicle stick/ I have a dispenser of them filled with sticks, they came off a lunch vendors truck where they were used as coffee stir sticks, I find a lot of uses for them in the shop.

Pioneerguy600

Hey, Jerry!

Another item that is perfect for this is a wooden shish-kabob skewer. They come in packs of 12 million and have a sharp, tough tip. They're also cheap, work well for cleaning crud out of nooks and crannys (flywheel fins, oye!), and I found a version that has one flat end that is even BETTER as a cleaning tool. Being bamboo, they are surprisingly durable and can be used multiple times even if they get repeatedly soaked.

Not to mention, of course, that they work well on the barby.

As far as assembling the clam shell goes, just go slowly. The pictorial Saw Dr has provided is dead on.

 

[brages]

Lol, I just figured out what I was doing wrong: trying to cram 46mm 029 Super rings in a not-so-Super 45mm bore:

The moral: NEVER ASSUME!!

 

[brages]

Gonna have some good compression with that end gap!! :bang:

 

[madman39]

Good thread!opcorn:

 

[brages]

Just to keep this thread going, I finally got some 45mm rings and tried putting it together. Small screwdriver to help the rings past the land between the transfers did the trick. IT WAS SUPER EASY ONCE I GOT THE RIGHT SIZED RINGS! No wonder I hadn't remembered it being so hard! :blob5:

 

[redunshee]

Gonna have some good compression with that end gap!! :bang:

Don't know how he got the piston in the cylinder!!!

 

[brages]

Don't know how he got the piston in the cylinder!!!

I didn't! But I sure tried my best!!

I ordered the wrong sized rings ASSUMING it was an 029 Super/290. With the right rings, it was a snap.