365 XT New P/C Needed

[CAMG3X]

My 365 X-Torq is need of a new piston and maybe a new cylinder. The cylinder has a considerable amount of "pitting" around the head with a slight knick out of the transfer port. I'll post pics below, need some advice as to whether or not I can get by with just a new piston.



Next question is where to order the piston and if aftermarket is an ok choice?
Thanks for the help

 

[mdavlee]

Put sandpaper on the old piston and smooth that out. Take and smooth the gouge on the transfer port and run it.

 

[CAMG3X]

Think the piston is beyond repair, has cracks along the skirt with chips of metal missing.

 

[weedkilla]

That is the best example I've seen of textbook detonation damage.
Definitely try and reuse that cylinder and try and get to the bottom of the issue.

Try reading this - http://www.klemmvintage.com/deto.htm
And any associated links.

Have a look at the fuel you are using, mix oil and ratio (too much oil and carbon deposits can cause detonation inducing hot spots), and see if you can reduce squish by removing the base gasket, also check flywheel location on the keyway.
Also have a look at that decomp valve, I find a plug that has 1/8 - 1/4 lightly coloured and the rest dark is a sure sign that the decomp isn't sealing.

 

[mdavlee]

Think the piston is beyond repair, has cracks along the skirt with chips of metal missing.

I meant just use the piston to sand that down a little to smooth it. I'm sure the piston is junk after that.

 

[CAMG3X]

Nice article Weedkilla! So the pitting of the head is the key sign of detonation?

Unfortunately I lent the saw to a co-worker when it blew. I believe the mix ratio was 50:1. Saw was ran hard for 8 hrs straight thinning each day. There are no mods on the saw, but when I broke it down I noticed a large crack in the muffler.

So what grit sand paper should I use to smooth it out?
Thanks for the help!

 

[gomoto69]

I would think removing the base gasket would give higher compression leading to more detonation, would it not?

 

[weedkilla]

I would think removing the base gasket would give higher compression leading to more detonation, would it not?

The pitting is all in the squish band - a key sign that uncontrolled ignition is occurring there. Reduce the squish band and there is less fuel there to combust and there is better cooling in that zone aswell. Yes compression goes up, but detonation risk goes down.

 

[TermiteBuffet]

Something went through the motor .That don't look like detonation to me ...Check all bearings well. ....[emoji200]

Pedal Tractor Loggin'

 

[gomoto69]

Ok, that makes sense

 

[mdavlee]

Was both circlips on the piston when you pulled it apart?

 

[redfin]

Perfect time to throw a 372 jug on it.

 

[mdavlee]

Perfect time to throw a 372 jug on it.

I wonder about using a meteor old style 372 piston and gutting the strato ports?

 

[CAMG3X]

Yeah, both circlips were on the piston when I removed it. Something definitely went through the engine, I believe it was a piece of the muffler at first followed by a fragment from the piston. I flushed out the crank case and mostly found minute flakes of metal with one shard about the size of a grain of rice.

The crank doesn't have any play on the clutch side and it seems to roll smoothly besides a tension point when the magneto hits the stator. The big end bearing may have a slight vertical play at TDC, hard for me to tell.

I believe the 365 x-torq has the same top end as the 372 X-torq minus the different transfer plate. Hope I can salvage the cylinder and just put in a piston. Noticed the OEM pistons are around $90-$100 while aftermarket are ~$35. Or there are full P/C aftermarket assemblies for $110.
http://www.ebay.com/itm/HUSQVARNA-3...454?pt=LH_DefaultDomain_0&hash=item58b05cfa4e

Do you think the aftermarket kits are reliable enough?

Thanks

 

[redfin]

[QUOTE="mdavlee, post: 5400373, member: 237wonder about using a meteor old style 372 piston and gutting the strato ports?[/QUOTE]

Benefits Mike? Different crown or skirts lengths?

 

[CAMG3X]

Well after further inspection of the big end bearing at the bottom of the con rod I found some damage. A portion of the grids that retain the rollers have broken off, definitely the source of metal that I found inside the case. Here's a pic where you can see misalignment of the rollers and damage:


Guess I'm going to have to replace the crank as well, blow up was more catastrophic than I expected

 

[pro94lt]

Co worker should pay to have it fixed... is he paying for parts?

 

[redfin]

Well after further inspection of the big end bearing at the bottom of the con rod I found some damage. A portion of the grids that retain the rollers have broken off, definitely the source of metal that I found inside the case. Here's a pic where you can see misalignment of the rollers and damage:
View attachment 429620

Guess I'm going to have to replace the crank as well, blow up was more catastrophic than I expected

Oof, I don't like to read that, sorry. It does looks there is a nice coating of residual on there.

 

[mdavlee]

[QUOTE="mdavlee, post: 5400373, member: 237wonder about using a meteor old style 372 piston and gutting the strato ports?

Benefits Mike? Different crown or skirts lengths?[/QUOTE]
Not sure. I was thinking more on the lines of a lighter piston in there and cheaper. I guess I need to find one to play with and experiment.

 

[CAMG3X]

There's residual oil on the internals from flushing the case with mix. Then used a strong magnet to try and get any extra metal pieces out. Planning on picking up a case splitter and taking a further look. Still deciding on aftermarket crank and piston, any input?
Sounds like the aftermarket crank on Baileys is reputable, though thinking OEM piston is the way to go.