346xp cylinder gasket.

[Gerbutt]

Hiya

 

I'm fitting a new piston to my 346xp and I was wondering if this cylinder gasket looks right? It seems to cover those little ports more than the original does?

[Adamam]

No, that's not correct.

 

Should be like this one, which I just fitted today to a 353 from this seller so I can vouch for it being correct!

 

NEW HUSQVARNA CHAINSAW CYLINDER HEAD GASKET TO FIT: 346 , 350 , 351 , 353 | eBay

[Gerbutt]

Bugger, it says it's right in the packet, got it from that garden hire spares place off the net!

 

Maybe I'll just use the old one with some sealer on it?

[Gerbutt]

I've just order the one in the link, cheers for that!

 

Do you know the best way to clean the carbon from where the spark plug pokes through? Is that the squish?

[spudulike]

Just take a sharp craft knife, put the bolts through the gasket and cylinder to hold it in place and cut in to the gasket around those transfer ports to open them up.

 

It would work as it is but would reduce the velocity of fuel/air through the transfers.

[Gerbutt]

I'll have a dabble at that spud, cheers. What's the best way to clean the carbon out of the exhaust port and where the plug sticks through? Also, can a piston and ring be worn without looking so? I was hoping they'd look lime they needed changing but in all honesty they looked fine!

[spudulike]

I'll have a dabble at that spud, cheers. What's the best way to clean the carbon out of the exhaust port and where the plug sticks through? Also, can a piston and ring be worn without looking so? I was hoping they'd look lime they needed changing but in all honesty they looked fine!

 

I would scrape the port with a craft knife and use a little emery paper around the bevel of the port to make sure it is smooth. A dremmel with a carbide burr does it pretty well also!

 

The plug hole - just use a little penetrating oil and screw the plug in an out a few times and then clean with paper cloth. If you have a plug hole chaser, this will do it!

 

Piston wear - usually the ring ends become thinner and the piston skirts wear to the point you get piston slap. If you put the non ringed piston in the bore and wobble the skirts back and forth, it becomes pretty obviouse if there is wear. A set of vernier callipers will also help tell you if there is wear, just measure the lower skirt and compare to the top of the piston both across the bore and inline with it.

[Gerbutt]

Cheers spud, the exhaust port and concave bit where the piston sticks through are now carbon free.

 

I tried the old piston without a ring and there seems to be around 1/4 to 1/2 mm play.

 

What I was finding with the saw was it wouldn't rev cleanly unless I was really leaning on it, almost sounded like it was running to rich - but it wasn't! Maybe it was piston slap causing that?

[spudulike]

Cheers spud, the exhaust port and concave bit where the piston sticks through are now carbon free.

 

I tried the old piston without a ring and there seems to be around 1/4 to 1/2 mm play.

 

What I was finding with the saw was it wouldn't rev cleanly unless I was really leaning on it, almost sounded like it was running to rich - but it wasn't! Maybe it was piston slap causing that?

 

One method is to push the piston in to the bore so flush with the base of the cylinder, push one skirt hard to one side of the cylinder and a 3 thou feeler gauge and no more should be able to be pushed in to the skirt gap on the other side!

 

I tend to check compression with a Gunson Hi Gauge, do the skirt check you have just done and also push the piston with no rings up and down the bore with your thumb over the plug hole - you should get a good feeling of a compression buffer even without the ring - all are a bit subjective but are good for me - I also do use calipers and get a good idea of wear through this.

 

If the saw is a bit slappy, struggles to make 140/145psi and measures up with piston skirt wear, it gets a new piston.....a Meteor at £30 is really a no brainer decision!

 

Slap sounds worse at very low revs - it can sound like a very worn clutch so you can pull the clutch off, start it and roll down the revs and see if it slaps - more common on longer stroke engines - 026 and 038 are susceptible to this , the 346 less so as the piston is supported well with the cylinder bore extensions on the base of the cylinder......just what I have found, others opinions may differ - thats life:sneaky2:

 

I have had a MS260 in once that had a piston so slappy and worn, one of the skirts shattered!

 

Now fixed and running - I will put pics of a MS460 I am currently working on, one muther of a job:thumbdown:

[Gerbutt]

Hello spud, thanks for all the advice👍 I put the new meteor piston and ring in last week. The saw started easily and does seem to run better but I'd say it's still a bit gurgally when I'm not pushing it hard. What could be making it only clean up on the revs when it's under pressure? Maybe a little to rich?