Too port or not to port

[laweng]

Hey guys, i'm looking to rebuild my Husqvarna 365 special. I was thinking of doing port polishing and matching the intake and exhaust also a muffler mod, more than a full on widening and changing the timing, which is way over my head and should be left to the pros. I've never done a chainsaw but have done a lot of motorcycles and snowmobiles, same principal just make it flow better I think. My question, by not removing much metal and just cleaning and polishing the ports, is this worth the effort and will I sacrifice the low end torque?

 

[nmurph]

I know this is thread is a bit old, but it was also posted the day before the hack so I will take a stab at it.


I would not bother polishing and port matching alone. A muffler mod will produce a bigger increase by far. You can do a very simple port job of widening the intake and exhaust to 65% of the bore, matching the bottom of the cylinder to the crankcase, matching the intake and exhaust ports to the carb and muffler, doing a muffler mod, and deleting the base gasket (measure first). This will give you a very noticeable bump in power. There are a couple of things to be mindful of: don't remove too much from the bottom of the cylinder, and don't get too carried away in the intake. Removing too much from the lower transfers can destroy the charge velocity and getting too wide on the intake can open the carb bolt holes.

 

[nk14zp]

I know this is thread is a bit old, but it was also posted the day before the hack so I will take a stab at it.


I would not bother polishing and port matching alone. A muffler mod will produce a bigger increase by far. You can do a very simple port job of widening the intake and exhaust to 65% of the bore, matching the bottom of the cylinder to the crankcase, matching the intake and exhaust ports to the carb and muffler, doing a muffler mod, and deleting the base gasket (measure first). This will give you a very noticeable bump in power. There are a couple of things to be mindful of: don't remove too much from the bottom of the cylinder, and don't get too carried away in the intake. Removing too much from the lower transfers can destroy the charge velocity and getting too wide on the intake can open the carb bolt holes.

Do these tips apply to all saws like my 254xp and 266?

 

[nmurph]

Yes.