Snedding_J

Sorry if this question has been asked before. I'm going to be in the market for a new saw in the near future.

Not sure whether to get a 500i or 661cm. It'll be used mainly to cut up hardwood logs and to fell the occasional big tree.

I've had a go with a 500i (felled a couple of big'ish outsiders) which isn't enough to form a proper opinion. Although the throttle response was fast. What's the new injection system/electronics like?

Not used the 661cm. I owned a ms660 a few years back, if was a great saw - never any problems. Is the 661cm as good?

anybody that's using them a lot - thoughts? Pros/cons?

7 minutes ago, adw said:

Husqvarna have never produced a 16" bar, other than the domestic bar?

Never bought a Husky bar other than what a new saw came with, which was usually a 15". I used Oregon pro lite 16's for years, not sure if they're called pro lites now tbh

Always been a fan of a 16" bar on my felling saws, really liked them on the 262xp's - still have a 16 on my 560xp.

20" on the next saws up 046 or 372xp.

Quite liked a 28" on ms660.

All down to personal preference ?

1 hour ago, Wonky said:

somthing else to put in your reading list to cross reference ??

 

http://3cyl.com/mraxl/manuals/bell/performance-tuning-graham-bell.pdf

 

 

edit,, it will fill in those gaps and bits you don’t understand, as it’s written by someone else..   

 

one important thing,,, when measuring squish don’t use to thick solder. Use the thin stuff,, if it don’t get squashed because the squish is to big, twist two bits together..

 

having too small a squish on a saw will fûddy the thing up,(smash the top and maybe/more likely bend the conrod) when it gets hot and expanded... 20thou aka 0.5mm is the min 

 

Cheers for all this info Wonky, I'm going to have to learn how to read now ?. I've been looking into some basic small die grinders for the air line - one straight and one 90 degrees for the transfers. Hopefully they'll work, seem to able to get the carbide burrs and polishing stones for them.

12 hours ago, CutterSy said:

 

Yes that’s right, file down the flywheel key to allow the flywheel to advance a few degrees.

 

?

19 hours ago, Wonky said:

I,m not typing for the night.. but you really need to read the book, 

setting the squish is a good start, to to this the easy way is base gasket delete.. and or add a gasket to get the required squish.. the saddle screws sit to high on the 461 to allow the cylinder to sit on the crank case.. thus they need the tops taken down...

 

and that saddle is there for a reason

 

the bit I circled in yellow is the saddle and one of the screws..

 

it late and I’ve had beers.. so brain says sleep time ??????

 

tomorrow ?

Great, thanks Wonky ?

3 minutes ago, Wonky said:

That’s all in the mcdizzy and the 2stroke t h book... to advance and how much is enough.... if you know fuel then the answer is never the same

Will have to give mcdizzy a look. No two engines are the same. I may be picking your brains again bud ?

2 minutes ago, Wonky said:

Yeh also the 461 sans gasket... but you have to take the tops off a little on those 2 screws that hold the saddle in place,, ask if you don’t understand ?

Not quite sure I understand Wonky?

Cheers

32 minutes ago, CutterSy said:

Both saws respond really well given the right treatment. 461 benefits from some ignition advance, the muffler is easy to do as well.
560 has transfer caps so you can easily work the upper transfers, be very careful with the intake as they can’t really be widened because of the piston skirt. The muffler is a bit more of a pain because it doesn’t separate like the 461, I just cut out as much of the baffle as possible and open up the exit.
Lots of info out there. Everyone does it slightly differently, the only way to see what works is to try and test.

All this info is great CutterSy, I've got a good bit of mechanical background but not on modifying 2 strokes.

 So on the stihl ms461, how would you advance the ignition? Alter the key on crankshaft/flywheel? Sorry for all the questions, just really keen to learn about porting chainsaws.

5 hours ago, CutterSy said:

What saw is it that you are wanting to port?
I feel I should warn you, porting saws is addictive, once you go down this rabbit hole running a stock saw is just boring!
Its a good plan to just smooth out the ports first to get a feel for it, do a muffler mod as well. You will see gains from just that.
If you let us know what saw you’re planning to port I can help you with any knowledge I have of it.

Thanks CutterSy, I would like to port a Stihl ms461 and my Husky 560xp. I can imagine porting being quite addictive, a bit like always convincing yourself you need another saw! Any help and knowledge would be a great help. I'm new to the forum and it's been great having people get back to me with their knowledge and information - thanks again.

18 hours ago, Wonky said:

it’s a start

Gordons book

http://www.amrca.com/tech/tuners.pdf

 

and google mcdizzy,, maybe I’d better point you 

 

MacDizzy's Two Stroke Technology Exchange - TRX - YFS - YFZ - Glamis Sand Dunes

MACDIZZ.COM

---

Two Stroke Engine Technology Database, Large Two Stroke engine building / porting section. Visit the Glamis...

 

 

Cheers Wonky, really appreciate it. Will look it up ?

48 minutes ago, spudulike said:

The results are more torque, aggressive in the cut, higher revs in the cut, shortens cutting speed, you can lean on the saw more with less bogging etc.  Varies from saw to saw, there are always models that turn out better than others.

Yes, there is a percentage that most accept as the maximum you can go on port size but it doesn't work like that if there are other constraints of the engine design that stops you going to the maximum size - you have to understand how two strokes work and how the piston works in conjunction with the port openings and crankcase.

I have done a few saws with pop up pistons and turned down cylinder bases, they are an expensive option due to the machining so tend to keep it simple to keep costs acceptable....get 75% of the easier gains rather than spending days trying to get the last 25% for 3X the cost!

The only book that makes good reading is by Gordon Jennings, it gives a few pointers but is mainly aimed at motorcycle porting although it gives a good overall look at the subject.

It does make sense, got to way the costs against the performance gains. I'll look up the book by Gordon Jennings. Think I'll start by cleaning up the ports and removing any imperfections (lumps and bumps) in the casting. That should make a difference. I'm quite interested to check the squish and hopefully turn down the base of the cylinder (roughly the thickness of the gasket) to see if it raises the compression much and what the gains will be. Thanks again, might pick you brains again I'm the near future

4 minutes ago, Stubby said:

Spud did ...346XP 372XP 390XP  . Petemate did my 560XP  and the Walker saw shop my 395XP . Yes vast improvement . Picks up quicker drives harder , runs cooler ( helped by MM ) and just as , if not more reliable .  EG my 346XP runs a 15" bar , full chiz chain driven by an 8 pin powermate rim .

Impressive collection, all ported too. I've read that the 372xp responds well to porting. Hoping to port my 560xp in the near future.

7 minutes ago, spudulike said:

Yes, there are guidelines as to how large ports can be made, restrictive elements that can limit port size, minimum clearances piston to squish etc. I learnt some by looking online, some from reading a couple of books that I purchased and some by just developing my own techniques.

Just use a dremel with a carbide burr or diamond burrs for lighter work.

You can't put metal back on once you have ground it off so don't just think "wider the better" as many seem to think.

Great, cheers Spudulike. Do you get good results, more torque and RPMS? Yeah, definitely a little material removed goes along way. Is there a certain percentage of the bore/stroke dimensions the ports can be enlarged too? I've been reading about squish, have you decked the bottom of a cylinder to raise compression? If there's any books you could recommend, it would be much appreciated. Sorry for all the questions, not too many people this side of the pond interested in porting chainsaws.

Many thanks

21 minutes ago, Stubby said:

@spudulike   Spud ported most of mine .

Great, with a bit of luck he might see this post. I'm keen to have a go at my own. What models have you had ported? Did you get good improvements?

New to the site. Just wondering if anyone has any information on chainsaw porting? Not for a racing saw, just to get a bit more performance out them. Is there any guidelines to follow on how much material to take out? Got quite a lot of mechanical experience, just not on porting. What kind of small die grinders do people use? Hope I've posted this in the right place, new to the forum stuff.

Thanks in advance