334T muffler mod

[Treeaddict]

Can I just drill it to unrestrict the exhaust? Maybe double the opening?

Also, I’m assuming it would require tuning afterwards?

 

[Nutball]

In my opinion, it is a common misconception that tuning is required after a muffler mod. It may make it easier to hear what adjustment is needed, and it may affect idle in some way, but I wouldn't worry about it too much, just see how it runs. You'll have to search around for how people have modified that muffler, and which way works best. Check for any baffles and catalytic converters. Spark screens can restrict flow as well.

 

[Treeaddict]

In my opinion, it is a common misconception that tuning is required after a muffler mod. It may make it easier to hear what adjustment is needed, and it may affect idle in some way, but I wouldn't worry about it too much, just see how it runs. You'll have to search around for how people have modified that muffler, and which way works best. Check for any baffles and catalytic converters. Spark screens can restrict flow as well.

Good info. I haven’t yet been able to dig up anything specifically on previous mods but I’ll keep searching. I know info John sent before purchase said they were really woken up after a muffler mod.

 

[lxskllr]

I'd start by taking the muffler off and seeing what's inside. That'll give you a clue where to start. Easy is making holes or gills where it won't melt plastic without welding/screwing a deflector on it. If there's a baffle, that'll most likely mean holes rather than gills. Be conservative. Removing metal's easier than adding it back.

 

[Treeaddict]

Well, found no baffles in the muffler.

Found no one with muffler mod info on this saw.

I drilled (3) 3/16 holes on the bottom front and put it back together. It sounds good but I can’t really tell if it is performing any better. I really enjoy it’s new vocalization though.

 

[Nutball]

One 3/8" hole is a bit bigger than 3x 3/16". I'd go 1x 3/8 as a minimum on 2511t, max I'd do is 1/2" which is 2.37 times bigger than your 3 holes.

 

[Treeaddict]

One 3/8" hole is a bit bigger than 3x 3/16". I'd go 1x 3/8 as a minimum on 2511t, max I'd do is 1/2" which is 2.37 times bigger than your 3 holes.

This is a 334T. Does that change your recommendation?

 

[Nutball]

Not really, though I don't know the size of the stock outlet on the 334T, but since it is a larger engine than the 2511, it will need a larger opening than the 2511. I can understand using small holes, but try to have a total open area almost as large as the exhaust port. I think 85% as large as at the cylinder is the rule of thumb. Also, if possible, have the exhaust exit as soon as possible. The 201t would allow for a small hole directly opposite the port, but exiting too close to the port can be a problem too.

 

[Trains]

When you do a muffler mod, you often reduce the back pressure, and as a result, the rpm can be higher due to the better flow.
if the rpm is too high, say max rpm wot unloaded is 13000, and after the mod its 14500 ie beyond the specs, then yes, that definately needs a retune, by going richer on the H needle, to bring the max rpm back into spec.