MS310 Muffler Mod

Went to a friends house yesterday to fell a 34" diameter White Oak. After seeing and hearing my 390XP run, he asked me if I could do his MS310. I fabricated a new part for the original port cover. I used 1/2 " inside dia. conduit for the pipes. Retuned & tested it in some oak and maple. He is going to be really happy. Runs much stronger now. Here are the results.

i was really disappointed in my 310 until i moded the muffler . didn't take pictures but now i love the saw .it really improved the preforms. thinking of doing my 345 husky. h

When you say you fabricated a new part for the original port cover, do you mean on the back of the muffler facing the cylinder? I didn't think I would have to do anything with that part of the muffler. Also, how much adjustment did you need to do to the carb? I've been looking online for new limiter caps before I do mine and can't seem to find any. Might have to go to the dealer.

Matt

aandabooks said:

When you say you fabricated a new part for the original port cover, do you mean on the back of the muffler facing the cylinder? I didn't think I would have to do anything with that part of the muffler. Also, how much adjustment did you need to do to the carb? I've been looking online for new limiter caps before I do mine and can't seem to find any. Might have to go to the dealer.

Matt

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The exhaust port cover is attached to the front with the 3 threaded rods. I used a piece of 1/16" steel, scribed the outline of the original cover, used tin snipes to cut and drilled the 3 holes. The limiter caps come off by screwing a small screw into the cap gently until it feels seated. Once it feels like it seated, give it a pull with needle nose pliers. Should pull the cap right off. There is a oval plate covering both caps that will pop off when you pull the first cap off. I put the caps back on. Wasn't necessary to buy new ones. It will run a bit lean after the mod so it needs to be richened up, which could not be do with caps on as it was already at its limit. I use a digital tach to set the H screw RPM's & idle. I do the L screw by ear while it is running. By turning it in clockwise, it will start to lean out (the RPM's will increase). I then back it out counter-clockwise about a 1/4 turn. It shouldn't hesitate when you hit the throttle or have trouble when starting it. Hope this helps you. Any other questions, feel free to e-mail me.

Russ

I see now. You completely blocked off the original output and put in new holes with the conduit welded in. I had the thought in mind of putting new holes behind the original plate and then milling slots in the plate and opening up the flow that way. I need to get another muffler though. The saw has less than two hours run time and 51 weeks of warranty left. Mod the spare muffler and put original back on in case of warranty work.

Thanks for answering my questions.

Matt

aandabooks said:

I see now. You completely blocked off the original output and put in new holes with the conduit welded in. I had the thought in mind of putting new holes behind the original plate and then milling slots in the plate and opening up the flow that way. I need to get another muffler though. The saw has less than two hours run time and 51 weeks of warranty left. Mod the spare muffler and put original back on in case of warranty work.

Thanks for answering my questions.

Matt

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Those series mufflers are cheap on Ebay! Thats where I got mine for the same purpose on my MS290.

Looks like about $30 with just using it BIN will get me a muffler to carve up.

Matt

Thats what I paid from cheapstihlparts. He is a good guy to buy from.

Looks nice - my buddy runs a 310, and I am going to see if I can convince him of the benefits of a good old muffler mod!

Ok guys, im getting in on this thread a little late, if i make the exhaust hole on the muffler cover 85-90% of the size of the exhaust port leaving the cylinder would that have the same effect??

chainsawaddict said:

Ok guys, im getting in on this thread a little late, if i make the exhaust hole on the muffler cover 85-90% of the size of the exhaust port leaving the cylinder would that have the same effect??

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That should work!

Bowtie said:

That should work!

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Thank you sir!

chainsawaddict said:

Ok guys, im getting in on this thread a little late, if i make the exhaust hole on the muffler cover 85-90% of the size of the exhaust port leaving the cylinder would that have the same effect??

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That should be fine - you might want to be a bit smaller at first. you can always make a bit bigger later if you choose to.