Another new guy with 350/353 to 346xp conversion questions

[pete031]

I've been lurking around here reading up on the older husky saws and have a line on a 353 to build a fun firewood/all around saw. Ordered the OE Husqvarna 44.3mm 346xp top end from HL, but noticed they also list the open port 45mm top end as a 346xp/353 top end. Did those go on a 346 at some point in production? Here's me and my 031 AV a couple years ago just for fun. 

 

[Spike60]

Welcome to the family Pete. What car is that in the background of the pic? 

That 45mm top end was never used on the 346, but can of course be bolted on. It was used on the 353 with a flat top piston and on the 350 with a dished top piston. Kind of a junk top end IMO, that has a harmonic vibration issue that likes to spit out the muffler bolts. Won't run with the 44.3 kit that you already have so you've made the right choice. 

[pete031]

That's what I thought, thanks for confirming. Looking foreword to digging into this saw. I believe the car in the picture was my folks late 70's Subaru wagon

[pete031]

Are there huge gains in going to a 359 carb or minor porting I could do myself ? Sounds like this should run pretty darn strong with the 346 top end, base gasket delete/squish adjustment minor muff mod and a good chain. Any other basic mods worth the effort while I'm in there? I'm an experienced mechanic but first chainsaw build. 

[mike_belben]

Porting is half the fun as long as ya dont screw up

[pete031]

Haha that's the only thing I'd be worried about. Is there a good porting recipe for a first timer to follow? 

[mike_belben]

Widen the intake and exhaust just a bit without changing the ceiling or floor heights.  If you are deleting the base gaskets and arent looking to gain torque at rpms expense it is okay to bring the exhaust port up the gaskets thickness worth. This will increase blowdown unless upper transfers are raised but theyre the hardest to do and easiest way to wreck the cylinder liner so id avoid on a good one first try.  Nothing wrong with just a widen and a shine up. 


Lower transfer inlet area can be radiused up with no risk and a substantial performance gain.  On yamaha blasters a gasket delete and lower xfer job is like adding 30cc. 

[pete031]

It sounds worthwhile to widen slightly and do a basic cleanup without changing port timing then. Anything to watch out for doing minor porting like this? Is there any risk of changing the usable rpm range or does that help on these saws? I'm looking for what I guess you guys would call woods mods for a fun, usable all around saw, not a race saw if you know what I mean. 

[Whiplash1]

Took my oe 346 45cc to a ported 50cc with carb upgrade and IMO the carb took this saw from nasty to insane for a 50cc 10lb saw! If your planning on porting why not do the carb upgrade? If you do though do complete from air filter to cylinder, don't try savaging parts.

[pete031]

Is that a 359 carb and intake tract that you did?

[Whiplash1]

Is that a 359 carb and intake tract that you did?

357 filter and elbow

[mudfarmer]

Well... thanks a lot!   :

Now I want to make my 346 a 50cc and slap on this extra 359 carb but shouldn't tear it apart right now and might have to try to find another. SOunds like the funnest thing since roman candle fights

[mike_belben]

Im waiting on a 346 block to fall in my lap.. Have a big bore top in the box and a 359 parts saw too iirc.  My ported 026 will be done before then i think.


Just watch it you dont widen into the ring gap. Try to bring round or oval corners into soft square corners to get more flow. No knife edges in the transfers.. You want soft smooth radius shapes for air to flow over.