3120xp jug & piston options

[Sierradmax]

I won an ebay auction on a 3120xp powerhead that needs a new top end. I plan on slowly rebuilding the saw and using it for milling purposes.

I don't see a meteor replacement as an option but plenty of $100 Chinese kits, which IMO isn't justifiable on a $1000 saw. OEM is upwards of $350-$400. Is this my only good option?

 

[Chris_In_VT]

Used OEM.
Ask around, shop around, something will pop up.
Not ideal if you need it right NOW however.

 

[blsnelling]

OEM only for me, especially on that saw. Contact one of the several dealers on the forum for a better price.

 

[Jacob J.]

Spike60 can help you with a good price on OEM parts. He's very good to deal with.

 

[mr.bear]

I won an ebay auction on a 3120xp powerhead that needs a new top end.

Pics?


Sent from my iPone using Tapatalk

 

[Sierradmax]

I received the saw last night and started tearing it apart. No ID tag so no way of determining the saws age.

1. The saw has a "black coil" and a previous owner didn't set the gap correctly and the coil rubbed on the flywheel. Can anyone tell me how to test a coil and see if it's still good? Is this one limited to 9600rpm's typically on 3120's?

2. At first glance, the carb has two needles. I haven't cleaned it thoroughly but is this one fully adjustable?


3. I pulled the muffler and the piston was at TDC. Looking through the muffler port, the piston skirt was like new. I thought I would be lucky! Unfortunately, after the crown was visible, I could clearly see it's toast. After pulling the jug, it was confirmed.


4. Now the jug... Cylinder walls look real good. No aluminum transfer but some light scratches on cylinder walls which I think can be had with a little bit of scotch-brite. Top of the cylinder is all banged up however.


What I can't tell is if the jug is OEM or aftermarket. Casting looks good with no defects. Transfers, intake, & exhaust ports are symmetrical. From Husqvarna's IPL's, the images depict "slots" cut into the jug with the muffler bolts inserted while the nuts are at the muffler end.

All aftermarket jugs have threaded castings for muffler bolts and even this OEM unit as well.
http://www.ebay.com/itm/HUSQVARNA-n...838?pt=LH_DefaultDomain_0&hash=item462cdd4ebe
Mastermind's 3120xp build has threaded castings.?
http://i1160.photobucket.com/albums/q498/Mastermind7864/Husqvarna 3120/3120029.jpg

 

[Gypo Logger]

Looking at the pics it makes one wonder what the saw was used for. It almost looks like charcoal dust as though it was used to cut fire kill.
It also looks like something was peening the top of the piston.
Good project though

 

[blsnelling]

That damage to the p&c is from detonation. Have Randy cut the squish and install a new piston.

 

[Sierradmax]

I figured cutting squish & base would do but did anyone notice the flywheel rub on the jug? Indication that the cylinder has been cut already?

 

[blsnelling]

Check your crank bearings closely.

 

[Sierradmax]

I plan on replacing them along with new seals.

 

[Jacob J.]

That's not the fully adjustable carb- that's the one that has the fixed high speed.

 

[Jimmy in NC]

The 3120 I had looked identical on the top of the piston and cylinder, but mine was also very scored.

Detonation is the cause.. but the cause of the detonation??? Poor fuel? Lean condition?

 

[Sierradmax]

I noticed a couple of ball bearings missing from the pto side crank bearing but not found in the crankcase, cylinder, or muffler.

 

[burnses]

probibly in the bottom of the cutters boot!

 

[Chris_In_VT]

Yup, looks like detonation to me. I rebuilt a 385xp that looked almost exactly like that.
Jug
[photo="medium"]1011[/photo]

And slug
[photo="medium"]1015[/photo]

 

[Big_Wood]

just so you know guy, that detonation does not hurt the saw whatsoever. i would clean everything up, assemble, and run her. black coil is limited to 12k. of course, i say that piston ( as long as the skirts are fine) is just as good as any but the picky members of the forum will say it's bad but they think even a nick is bad cause that's what they were taught by all the other picky members who have been here forever. most of these guys admire their saws sitting on a damn shelf most the saws life too rather then actually use them so how do they know. they just wanna know a nice shiny piston is in there. last 3120 i had like that it was so bad i had to clean up the edge where the crown meets the skirts cause the edges were so sharp and it still runs milling hard nearly everyday. sold it to a guy who makes custom furniture out a drift wood he mills. i'd clean up, assemble and run it on high grade mix but i'm not picky.

 

[Chris_In_VT]

Yeah, my 385 still ran alright with that piston, but it had around 120lbs compression. Not scored at all, just worn out I think. Broke in meteor piston is at 155lbs now.

 

[Big_Wood]

Yeah, my 385 still ran alright with that piston, but it had around 120lbs compression. Not scored at all, just worn out I think. Broke in meteor piston is at 155lbs now.

the 3120 piston would not have that low of compression because of the piston though and i doubt it was the reason yours was low as well.

 

[burnses]

looks aren't everything....I guess if you wanted to scrutinize that piston in detail the deal breaker would be if the ring groove is binding the ring. You could ck the land clearance if you had the spec new.....probably around .0015-.002 inch or something like that. I ya really wanted to go for it with a good mic. measure about .100 below ring and .100 up from the skirt and see if the piston has any taper left or that the skirt is not collapsed. Hell put that piston in the lathe and take .010 off the edge where all the peppering is to make ya feel better and go for it....probably run some decent gas and at least 40/1 I bet........ck the ignition full adv too ya never know....

good luck