Stihl 390-Bailey's Short Block rebuild

[WoodchuckPaddy]

I just received my Bailey's short block for a rebuild in my saw (390).

Reason for rebuild - I traded for the the saw, It ran great for about a season until it didn't and I noticed that the spark plug hole had been messed with and a heli-coil with goop had been installed. The fix worked good enough for the guy to got rid of it. Now however, it's all loosy goosey and f'd up, you can't replace the plug and it isn't right, The saw is in otherwise seemingly good condition.

So here I am with not much $ into the saw.
I like the saw and it's capabilities for my use.
I felt that the Bailey's short block solution made sense.

My saw does not have a compression release, so i want to plug the hole.
Metric nor standard bolts don't seem to be the right thread.
1/8th inch pipe thread seems to work.

My question to the experts:
Should I use a brass 1/8" pipe plug?
Should I just get a compression release from Stihl and modify the housing (I don't really want to do this, I'm stock kinda guy...)?
Will high temp loctite hold up on the threads, or is there something else I should use?
Does Stihl make a purpose made plug for this?

Also, for the cost, should I just replace the fuel line while have the saw apart to avoid a future failure?

Any suggestions?

Thanks in advance.

P

 

[Adirondackstihl]

I cant answer the decomp question 100%, but I'm sure a Husqvarna decomp plug will fit.
While its apart, I would replace the fuel line/filter & impulse hose. May also think about a carb kit......it wont hurt.

 

[nstueve]

x2 on impulse and fuel line and filter

skip the carb kit but take the carb out, clean it, and make sure the diaphram is still soft and flexible...

I like using a ultra sonic cleaner with seafoam...

 

[Adirondackstihl]

x2 on impulse and fuel line and filter

skip the carb kit but take the carb out, clean it, and make sure the diaphram is still soft and flexible...

I like using a ultra sonic cleaner with seafoam...

If I take a carb apart thats been used for some time, for any reason, I tend to at least replace the diaphragms, check needle & metering lever for wear. Saves alot of time and guess work which = $ in my pocket.

 

[roostersgt]

Northwoodsaw, a sponsor, sells the correct thread decomp plug on their website. I've used several of them as that class of saw doesn't really need a decomp and it's just another potential source for an air leak issue.

 

[H 2 H]

Your Stihl dealer has the right plug for the decomp hole mine came from a 440 for about $2

Change all the hoses and intake boot since your in there they will cost you about $25

Carb kit was $8

So your into the saw for another $35

All this means is you don't have to worry about it for a couple years :msp_biggrin:

 

[zogger]

Seems like you could have maybe fixed the sparkplug hole with one of those timerserts the guys here talk about all the time..

With that said, nothing wrong with a total rebuild either! Keep the old stuff for spares (find another junker to fix up), and fix the spark plug hole anyway.

 

[fearofpavement]

Don't use a pipe plug, that is incorrect. The decomp is a standard metric thread. I just did this on an 029 to 039 conversion and I think I mentioned the thread size in the thread. I will look and see and post it here. I shortened a bolt and installed it with a copper washer. (a copper washer kit is available from harbor frt for cheap and it will have a size that works.)

 

[fearofpavement]

The decompression thread size is 10mm x 1.0mm.

The thread I was referring to is here http://www.arboristsite.com/chainsaw/205977-5.htm

It goes through diagnosis and rebuild of the 029 Super including some errors I made. It runs great now. I modded the muffler but haven't run it since.

 

[petersenj20]

Now you tell me thread size.

I ordered this kit about a month ago (So cheap - i'm thinking about making bikes with 'em) for a 039 and just installed today. Hence the search tonight.

I went to ACE to match up and the metric didn't seem to fit as well as the 3/8" fine thread (I think 3/8-24) did. Which means, before I run it anymore I need to pull half the saw back apart to replace.

On a side note I need to break it in so will post another thread.

 

[WoodchuckPaddy]

Thank yous, a plan and another question...

All good stuff here.
Thanks for the advice.
I'll keep you posted on progress.

I started tearing down saw last night.
I just have the oil pump to remove and believe I'm good to pull the cylinder.
Then, lot's of cleaning.

Here's my plan:
1. replace impulse line, fuel line and, intake boot per H 2 H sugestion.
2. get proper decomp plug from Stihl dealer, use copper washer (if not provided) and copper gasket spray when installing.
BTW on this issue- I tried a 10 x 1.0 mm bolt at the hardware store and threaded it about a turn and it seemed to bind, which is why I tried the pipe thread. I'm not second guessing, perhaps the tolerence on the saw or bolt were out a bit. I didn't want to force it....
3. I'm going to go with nstueve on the carb. I don't really want to monkey with it. If it gives me trouble, it is easy enough to get to and remove for a rebuild.
4. Sea Foam sounds like good stuff, never used it, will try it.
5. probably could have gone with the Timersert, but felt that someone had already monkeyed with it and failed. Also, this was an easy way to get some experience dismantling/assembling this type of saw. In a nutshell, I wanted to fool around with my saw in my shop

Next question:

Obviously, I want to clean all the parts before reassemly, after a brush and clean to get most of the gunk off, can I put these parts into a dishwasher to give them a good hot steam cleaning? Will they tolerate the high water temp w/o deformation/melting?
Is there another way to clean up all the nooks and crannys of these plastic parts?

Thanks all!

 

[WoodchuckPaddy]

In the Dishwasher...

...just the plastic parts.

 

[WoodchuckPaddy]

Stihl 390-Bailey's short block rebuild-recap

All,

Reporting in.
Saw is rebuilt, reassembled, and running.
Just waiting to put it to some wood to help with the break-in.

After completed disssassemby, degreasing and cleaning, the short block went in fine, everything bolted up.
I followed advice and replaced impulse line, fuel line and intake manifold.
I soaked the carburetor in Seafoam, but did not use and ultrasonic cleaner 'cause I didn't have one.


I'll post anything significant happenings on the saw as I use it.
It appears this shortblock option from Bailey's is a winner.

Thanks to everyone who submitted advice.

Best,

Patrick


View attachment 255336
View attachment 255337

 

[zogger]

All,

Reporting in.
Saw is rebuilt, reassembled, and running.
Just waiting to put it to some wood to help with the break-in.

After completed disssassemby, degreasing and cleaning, the short block went in fine, everything bolted up.
I followed advice and replaced impulse line, fuel line and intake manifold.
I soaked the carburetor in Seafoam, but did not use and ultrasonic cleaner 'cause I didn't have one.


I'll post anything significant happenings on the saw as I use it.
It appears this shortblock option from Bailey's is a winner.

Thanks to everyone who submitted advice.

Best,

Patrick


View attachment 255336
View attachment 255337

thanks, good write up! The only thing I am still wondering about their shortblock is real world longevity, due to the circlips and rings. Any number of times we have read here go for OEM or caber rings etc when getting the aftermarket kits. *shrugs*

I will be doing one of these shortly, see how the finances go. I might just go for the piston and cylinder though, even cheaper than the complete shortblock. This one I am doing is really less than a year old I think, relatively new anyway, and wasn't used much at all and 100% certainly straight gassed according to the guy I got it from. Although those shortblocks are darn handy and quite a deal really. Wish they had that for a number of different saws actually.

 

[H 2 H]

I have atleast 10 + tanks thru mine and it s getting stronger

It runs a 25" 3/8's ES b/c :msp_tongue:

 

[ri chevy]

Nice

Looks good.

But where are the photos of the saw when it was apart?

 

[H 2 H]

Looks good.

But where are the photos of the saw when it was apart?

Here is one that is in my barn :msp_tongue:

 

[ri chevy]

Yikes! Another 390 kit? :hmm3grin2orange:

 

[WoodchuckPaddy]

Ok, so I've run it through a couple of heat cycles. Starts 2nd pull, idles perfectly, decent throttle response.

Question; It seems to smoke a bit more than it should??
(it could just be that they all smoke and I never really noticed it.)
Ill start my 029 tomorrow to compare. Otherwise I'm guessing that is normal and should get better (less smoke) as break in is complete.
Mix is Stihl oil at 50 to 1, pretty fresh.

Thoughts?

 

[woodgrenade]

Probably some extra assembly lube in the jug from the factory. Should burn off as you use it.