Dual port muffler on a 660

[RobRainford]

Installed this today and got it tuned. Tops out at around 12,800rpm, compared to the standard exhaust topping at 13,200

 

It seems like there's a lot more power available. Can't wait to cut some wood with it!

 

[ame=http://www.youtube.com/watch?v=2H4tBEMVhwM]YouTube - ‪STIHL MS660 Dual Port Exhaust‬‏[/ame]

[Mike Hill]

Installed this today and got it tuned. Tops out at around 12,800rpm, compared to the standard exhaust topping at 13,200

 

It seems like there's a lot more power available. Can't wait to cut some wood with it!]

 

Have you not got the numbers round the wrong way mate?

[spudulike]

Should unleash a bit more power - Muffler mods always work better on modern bunged up 114db mufflers.

[RobRainford]

Have you not got the numbers round the wrong way mate?

 

No, guy at the shop said with the less restrictive exhaust it was running lower, but higher with the stock exhaust after he had a go.

 

Spud: i hope it does! I'll have a go tomorrow and see what it's like.

[Tree Man Tom]

Surley its all about chain speed, which is related to revs. Sounds like you've just de-tuned your saw? Made it slower?

[Mesterh]

So who tuned it and what did they do exactly?

 

It should rev higher and stronger.

 

 

Well as far as I know anyway.

[spudulike]

Got to say I upped my 345 by 500RPM when I did a muffler mod, the mod will lower running temperature allowing for a faster running speed, the mod should also allow for higher RPMs in the wood without bogging so much so it isnt all about top end revs out of wood but also about the rpms under load which should be higher with more power from the muffler mod.

[RobRainford]

The pickup is faster when revving the saw, the revs are only what it is full load out of wood, I would think it's going to be able to hold higher revs in the wood, with a shorter rpm range for power, it should be quicker, if thats right.

 

He set it slightly richer as stinks run weak and did some other stuff with the carb, new spark plug too. I can't remember all the details, but he knew what he was talking about and said he's never had a saw go wrong when he's messed with it! He wanted to alter the jets and the stops in the carb, which I may let him do to allow better adjustment, but I'll see after it's had some wood time!

[Johny Walker]

iv had 66,s for yrs & never had the need to tinker with them ,as they have ample power ,& you should never rev a saw on a hard serface like that as it can crack the casing!!!!!

[armchairarborist]

a bit of noise pollution never hurt anyone:thumbup:, but i had a vicar screaming at me (proper mad, red face and twitching) when i had been ringing up logs for a few hours in the next garden with same mod on ms460:lol: