what to do with ms390

So I picked up my ms390 2 seasons ago. Was cutting a tree for a friend. Got all done with one tree when their son came over and had one he wanted cut up so he could move it. I get there, and the saw won't start. I sent it into the shop and was told I was 125 psi short on compression. He said I could put a set of rings in it and use it for a while, but the right way to fix it would be to put a new top end. He said the cylinder wasn't scored. He said I was running very very lean, which I didn't like, since he was the only what that's worked on it.

Anyways, I kept my saw, and have since upgraded to a ms660. I'd like to put a big bore kit on my 390, but from what I have read, no one makes one. I'd like to try to rebuild it myself, to save some dough in having someone else do it, and it gives me something to do. I also wouldn't mind having a backup saw. For the amount I was quoted to have the shop fix it, I could spend a little more and have a brand new saw.

What would you do with something like this? Worth the time and money to get it going again or just scrap it out? Your thoughts.

GM_Grimmy said:

For the amount I was quoted to have the shop fix it, I could spend a little more and have a brand new saw.

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There's your answer. And don't make it a 290/310/390 this time..
Aim at a 50 or 60cc pro saw to go with your 660.

I think your dealer is jerking you around. Find a new dealer 1st. I personally thing that saw is worth a set of rings...it's only 2 seasons old. Pull it apart and inspect it yourself.

Wildman1024 said:

I think your dealer is jerking you around. Find a new dealer 1st. I personally thing that saw is worth a set of rings...it's only 2 seasons old. Pull it apart and inspect it yourself.

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:agree2:

For $30-$40 bucks you can get new piston and rings.I would do that.Make sure you clean all aluminum transfer from cylinder.Plenty of threads on that.390 is the big bore for that saw.No aftermarket 390 jugs available that I've seen.
Thall did a rebuild with pics.It was a 290 to 390 conversion(same saw different motor).If you search it up you can get familiar with process before you start.If you post it I'm sure people will jump in to help you through.

Before you do anything major I would find out why it was running lean.Could be air leak,fuel line,trash in carb,etc.If dealer set it up lean,I wouldn't let him touch it again.

I bought one of these for BIL and in 12-14" wood the biggest difference between that and my 660 was 4lbs.(including bar)

if there is no scoring above the exhaust port, clean the AL off with muriatic acid and repalce the piston and rings. baileys has them for about $35. while you have it apart, go ahead and replace the fuel line. they are prone to cracking after they get a few years old. this is likely what happened to your saw.

Your dealer is jacking you. If the cylinder is fine, put a new piston / ring in it. Muff mod it and use it.

you're not going to believe this but I took it to another shop to get a second opinion and 15 minutes later I was on my way back out with a saw that runs fine. The decompression plug was stuck in. The guy that worked on it used to work at the other shop that told me that I needed a new top end. They didn't even charge me, which I tried to pay them but they would take it. I know where I'm going for parts and me service work now, that's for sure. I haven't called the other shop yet, as I was running late for work. They might get a nice call tomorrow though.

Thanks all for your help and input!! Now my back up saw is running, I might try this muffler mod out, but I need to read up on the how toos more before I attempt it.

GM_Grimmy said:

you're not going to believe this but I took it to another shop to get a second opinion and 15 minutes later I was on my way back out with a saw that runs fine. The decompression plug was stuck in. The guy that worked on it used to work at the other shop that told me that I needed a new top end. They didn't even charge me, which I tried to pay them but they would take it. I know where I'm going for parts and me service work now, that's for sure. I haven't called the other shop yet, as I was running late for work. They might get a nice call tomorrow though.

Thanks all for your help and input!! Now my back up saw is running, I might try this muffler mod out, but I need to read up on the how toos more before I attempt it.

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Glad it worked out for you. Shame your old dealer was a "Tool". That 390 should serve you well. Mod the muffler and retune it and it will be a great 60cc saw for your needs and serve you well.

Typical dumpster candidate - not a very good saw! :censored:

SawTroll said:

Typical dumpster candidate

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Yeah, the original dealer!

Good for the guy getting his second opinion and learning a coupla things along with having a perfectly good backup saw for about anything he'd need one for.
My 039 will jump and growl if needed.

So...

Easy, ST. You'll scare him away before the CAD sets in!

Poge

SawTroll said:

Typical dumpster candidate - not a very good saw! :censored:

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Sorry it's not a 346. If he likes it then that's all that matters. It may serve him well.

SawTroll said:

Typical dumpster candidate - not a very good saw! :censored:

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Totally disagree with you on that one Niko. Yes, it's a clamshell and there are better designs. I have a 310 with hundreds of hard hours on it, never had a problem and it still runs as good as any of my other saws. My friend has the 390, no problems with it.
Muff modding these saws makes a great difference.

I'm withe the others that say its worth fixing. Cost wise though, you would have to do it yourself. Several great threads here on re-building that series of saw. Assuming the cylinder is salvageable, and the crank seals don't get mangled, you could have that saw running for less than $75. Just make sure to find the exact reason it roached in the first place.

Arrowhead said:

Totally disagree with you on that one Niko. Yes, it's a clamshell and there are better designs. I have a 310 with hundreds of hard hours on it, never had a problem and it still runs as good as any of my other saws. My friend has the 390, no problems with it.
Muff modding these saws makes a great difference.

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Sure they mostly will last for a while, but that doesn't change the fact that they are well outdated and POS cheap designs!

Sorry to say, the POS factor was usually not reflected in the price of a new one.

I wondered how long this would take. Same Troll Song, Different Troll Channel.

SawTroll said:

Typical dumpster candidate - not a very good saw! :censored:

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Have you ever even ran one or is this another book of ST statement!<a href="http://www.sweetim.com/s.asp?im=gen&lpver=3&ref=11" target="_blank"><img src="http://cdn.content.sweetim.com/sim/cpie/emoticons/0002053E.gif" border="0" title="Click to get more." ></a>

SawTroll said:

they are well outdated

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What does that even mean? If a thing does the job it was designed to, isn't it up-to-date enough? Is a Deuce Coupe any less awesome for being 80 years old? Don't they call it "Classic Rock" for a reason?

GM_Grimmy said:

The decompression plug was stuck in.

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I was going to tell you to check that. Glad it worked out. I had a 390 for 2 years and it was hard to sell it, but I needed the money for a 441 that was calling. I would buy one again, for the right price.

man, I love my 390. had it for a year now. Started out as a 290 and i put the 390 crank/rod/jug/piston. Its powerful and relatively light. I like it. Thats all that matters. It runs and starts everytime.

And for Saw troll. Man your a outspoken arrogant fool. 28,000 post doesnt make you smart it makes you annoying. i get so sick of reading these forums and having to read your biased ignorant comments. Jeez man if you crapped golden nuggets i could understand but im sure your excrement smells jsut the same as the rest of ours.