Modified muffler wanted for stihl

[normandylumberjack]

Hello people,

I need a replacement exhaust for my trusty ms390, and have heard a lot of people singing the praises of modified mufflers.

Can anyone tell me if they are available pre manufactured? I dont have the skills to make my own, and think that there must be a gap in the market for a pre fab offering.

I use this saw commercialy along with pro grade stihls, and cannot fault it for reliability.

[Cut4fun]

I'm not a fan of these models but at least you got the 65cc top on the heavy beast.

 

You can do a muffler mod on a MS290 310 390 in about 30mins. I have seen 23% quicker cuts on a 290 before. Just a tad less from the 390.

 

If you want I will walk you through it in PM or emails. I have a thread on the 390 I did this year on Chainsawrepair site. I dont know if the embedded pics will shoow up. I know the photobucket one will.

 

The 390 I didnt put the spark arrestor back in but I did on the 290 last year.

 

Oh, Dont fall for that $100 muffler mod crap people sale online.

 

Link 4 you. Stihl MS390

 

You will need to re-tune carb afterwords. Richer.

Edited November 27, 2011 by Cut4fun

[spudulike]

I'm not a fan of these models but at least you got the 65cc top on the heavy beast.

 

You can do a muffler mod on a MS290 310 390 in about 30mins. I have seen 23% quicker cuts on a 290 before. Just a tad less from the 390.

 

If you want I will walk you through it in PM or emails. I have a thread on the 390 I did this year on Chainsawrepair site. I dont know if the embedded pics will shoow up. I know the photobucket one will.

 

The 390 I didnt put the spark arrestor back in but I did on the 290 last year.

 

Oh, Dont fall for that $100 muffler mod crap people sale online.

 

Link 4 you. Stihl MS390

 

You will need to re-tune carb afterwords. Richer.

 

Spot on - done all mine myself, holes opened up with a drill or diamond bit in a dremmel and silver solder to braze on a new pipe if needed - BBQ paint or stove paint to finish:thumbup:

[normandylumberjack]

This would have to be done to a new muffler, as the old one has a piece broken off and rattleing around inside. Im worried that if i drill too big a hole that its money down the drain. Also the braizing, is it strictly necissary? instead of a spark screen, could i drill multiple small holes?

I know i sound like im fussing, but i really am that stupid when it comes to maths and metal working!

 

What size of drill bit would you recomend for one hole?/ multiple holes & how many?

[Cut4fun]

No welding or brazing on mine. I dont like little pipes. Just a drill bit is all that is really needed on 290-390 muffler.

Now I do use dremel on the deflector.

 

If you dont require a spark arrestor, toss it. No need for small holes like that and wouldnt pass as a spark arrestor if required.

 

Do you know how to re-tune a carb? Have you pulled the H or L side stop already?

[normandylumberjack]

I have tuned before, but any tips would be great. What size hole would you recomend drilling? I have read about 80% of the input, but maths was never my strong suit.

[Cut4fun]

Make that holes.

If you only have 2 slits on top of muffler from OEM. I open both of those and put 1 more in between those. Then I do 3 more below under baffle just like the top ones.

Then I do 2 more bigger ones right in the middle of baffle. Then do the deflector as shown, by opening up outer part.

 

It's not rocket science. % 80 to 100 for me.

[spudulike]

80% of exhaust port area seems to be the norm!

[samthescam]

80% of exhaust port area seems to be the norm!

 

How much would you charge to do it? I'm thinking of doing the 261 or 201t cos it's so gutless. Just wondered how much it would cost me?

[spudulike]

How much would you charge to do it? I'm thinking of doing the 261 or 201t cos it's so gutless. Just wondered how much it would cost me?

 

If they are in warranty, I wouldn't touch them as it would invalidate the warranty straight away leaving you with no comeback if the saw fails.

 

If the muffler gets a mod then the carb would need a final tune - normally limit caps need to be pulled and refitted - would you do this or me - needing the whole saw to be sent!