290-390 Conversion / Any speciality tools needed??

[Adirondackstihl]

A friend just gave me an 028 wood boss and an 029 super. I've got the 028 up and running but the 029 unfortunately has a scored piston and a cylinder that can't be cleaned up. So I'm looking for an AM 390 kit. Any suggestions on 'the best kit out there'? I've searched a little for info but it seems most kits have had some issues. My crank and bearings feel good so I don't necessarily need an assembled kit.

Try to find a used OEM cylinder if possible.

 

[71dart]

Try to find a used OEM cylinder if possible.

Amen to that. Now where are all those cheap, good used 039 cylinders at?

 

[fearofpavement]

A friend just gave me an 028 wood boss and an 029 super. I've got the 028 up and running but the 029 unfortunately has a scored piston and a cylinder that can't be cleaned up. So I'm looking for an AM 390 kit. Any suggestions on 'the best kit out there'? I've searched a little for info but it seems most kits have had some issues. My crank and bearings feel good so I don't necessarily need an assembled kit.

Did you try cleaning up the cylinder? Sometimes they can really look bad and still clean up ok. I've cleaned cylinders before to find out they were or weren't ok but it's hard to tell unless you've made an attempt.

Regarding kits, I buy mine from Huztl which sells the FarmerTec brand. I have had good success with that vendor. I buy a lot of parts from Asia and have tried different vendors but have a pretty short list of suppliers I deal with. There's lots of options out there. If you order from Asia, you need a lot of patience as it can take as much as a month for the shipping, customs, etc.

 

[Paragon Builder]

Removing the engine pan is not necessary and a waste.

Agreed.
I just did a 290 to 390 conversion yesterday and realized why bother pulling the bar stud and pan when I can place the new guts in the same pan. I used a huztl kit and it runs pretty strong. Got 4 tanks through it and it's getting stronger. My buddy should be happy with it!

 

[71dart]

Did you try cleaning up the cylinder? Sometimes they can really look bad and still clean up ok. I've cleaned cylinders before to find out they were or weren't ok but it's hard to tell unless you've made an attempt.

Regarding kits, I buy mine from Huztl which sells the FarmerTec brand. I have had good success with that vendor. I buy a lot of parts from Asia and have tried different vendors but have a pretty short list of suppliers I deal with. There's lots of options out there. If you order from Asia, you need a lot of patience as it can take as much as a month for the shipping, customs, etc.

Thanks. I'll look into FarmerTec. I have cleaned up cylinders with good results and tried on this 029 but one long, deep gouge above the exhaust port just won't clean up.

 

[HusqyStihl]

Where or who is a good person/place to purchase some new MS390 stickers??

I emailed Stihl Virginia and asked for some decals or stickers and got 3 in the mail today. Just ask and thou shall recieve!!

 

[towingace]

Try to find a used OEM cylinder if possible.

Key word: TRY

I'm sure there's a couple out there...somewhere.

 

[HusqyStihl]

Total teardown of MS290 in prep for MS390 Top-End: 27 minutes! Easy as hell

 

[HusqyStihl]

 

[HusqyStihl]

There is no gasket between top and bottom of an MS290. What is the red compound between to two used as sealant? Ive heard of yamabond and other things. What good to use??

Any help is appreciated,

Thanks,
~Moose

 

[fearofpavement]

You need a sealer suitable for fuel immersion. I personally use Permatex Motoseal-1. It's a gray colored compound. None of the silicone gasket makers are suitable for this application. They'll work for a while but not long term. Dirko, Yamabond, Motoseal, and others are the appropriate ones.

 

[HusqyStihl]

You need a sealer suitable for fuel immersion. I personally use Permatex Motoseal-1. It's a gray colored compound. None of the silicone gasket makers are suitable for this application. They'll work for a while but not long term. Dirko, Yamabond, Motoseal, and others are the appropriate ones.

Thank ya! Knew i was forgetting something. Also poked 2 tiny holes in this line pushing it through the housing... Bummer, gonna rob one off the other 290 until i get a replacement.

 

[fearofpavement]

pull lines through, don't try to push them. That impulse line needs to be attached to the cylinder early in the assembly process and then feed it through the hole in the rear handle along with the wires before attaching it to the engine housing.

 

[HusqyStihl]

Luckily a buddy is hookin me up with a replacement. Thanks for the tip, never disassembled a 290 prior to this one so could has been worse i guess. Ive got 2 to play with but only doing one swap-top at a time to see and feel the difference.

 

[HusqyStihl]

I've removed tons of the studs and never ruined one. I usually can get them out by double nutting them but have also used a channellock multiple times. If you use a channellock (about a 430 size works well) grip it close to the body of the saw. It will screw up the threads some but guess what? those threads aren't needed as the bar and clutch cover extend past that area.

You'll need a good quality T-27 Torx (I use one with a drill driver as it really speeds things up) Hand torque the reassembly, not with a power tool.

An impact works well to take the clutch off. (I use an air driven 3/8 butterfly) remember it's backwards threads on the clutch and regular threads on the flywheel.

To remove the flywheel, I loosen the nut with a 1/2" 3/8" drive deep well socket. (it's 13mm but the 1/2" fits a little tighter) Then I hand screw the nut back down and then back it off about 1 full turn. I then get a good grip 0n the base of a flywheel fin with a pair of duck bill pliers and holding the saw a couple inches off the bench I give the socket a hefty whack with a 12 oz brass hammer. One hit will typically loosen the flywheel.

On reassembly, I put the engine together, let it sit overnight and then pressure test it the next day before I assemble the engine into the engine housing. (it takes some spacers/bushings to take up the bolt length)

Everything else is undo what you did previously. If it's an aftermarket cylinder, many of these have the wrong size hole where the coil wire goes onto the cylinder. Use a #10 coarse screw in this spot.

Be sure to install the impulse line on the new cylinder before you get it all assembled as it's hard later.

Yes, retune when finished and go cut wood.

You speak of removing the flywheel, clutch, and removing alot more things. I basically removed the plastics after the carb related parts, exhaust, handlerbar and 4 bolts on the bottom holding the cylinder on and cylinder came loose with a little nudge, pulled it off and then sent the c-clips flying across the room (the little b*stards, still one missing) and she sits waiting for the 390 swap top. Not that i didnt wanna remove all that and was surprised how easy it was, i was glad i pulled those bolts even though i thought i'd be purchasing a new T-27. What are they torqued to 2000 ft/lbs with loctite? They were in there!! But came out no broken tools. Is there a reason im missing as to why the rest must be removed? It seems pretty easy to swing this job with much less work...

 

[a. palmer jr.]

If you have a 290 with a scored piston it sure is a lot cheaper to replace the 290 than to go to a 390. I'm not sure why the big difference in price..

 

[HusqyStihl]

My 290 run like the wind, no problems at all. I just fix thing that arent broken, can't help myself. Lol

 

[HusqyStihl]

If you have a 290 with a scored piston it sure is a lot cheaper to replace the 290 than to go to a 390. I'm not sure why the big difference in price..

A/M 390 tops from SawSalvage.com are 75$. @duke Theiroff

Great guy, very helpful and has a special going on Husqy 261/262xp air filters! lol kidding Chris

My two 390 tops will be here in the next couple days if not tomorrow

 

[a. palmer jr.]

A/M 390 tops from SawSalvage.com are 75$. @duke Theiroff

Great guy, very helpful and has a special going on Husqy 261/262xp air filters! lol kidding Chris

My two 390 tops will be here in the next couple days if not tomorrow

I paid $22 for a p/c for my 290 with free shipping, the 390 is close to $80 where I looked.

 

[HusqyStihl]

Was it Stihl or A/M?