460 and 660 work saws double build

[Signoflife]

I'm assuming the talk of a smaller gear on the drive, 7, will spin the chain faster like a smaller pulley would?

So will a bigger gear drive 8-9 give you more torque?

After reading the last post, I think I have it backwards.

This stuff is complicating...

Bigger gear = more chain speed and less torque, since the crank drives the sprocket/rim.

A gear with more teeth has to have more circumference / distance around the perimeter of gear to maintain and match the chain pitch spacing to the sprocket/rim teeth spacing.

So one rotation of crankshaft with a bigger gear moves the chain further than a smaller one.

Not to confuse but if you reverse the order and the chain was driving the sprocket the larger moment arm force acting on the crank would equal more torque, to the shaft.

 

[CHEVYTOWN13]

Cool beans.

I think I understand now.

I couldn't imagine it until I thought of a beach cruiser vs a 10 speed bike's gearing.

 

[Signoflife]

The 10 speed gearing is similar a little more complicated as the driving gears (at the pedals, similar to sprocket/rim) have two sizes the larger one (more teeth) gets you more speed but less torque and the driven rear gears (at the wheel shaft) have five sizes the largest gets you more torque (bigger lever arm / moment to the wheel) but less speed to the wheel as it has to go through more teeth for one rotation of wheel.

 

[CHEVYTOWN13]

Thanks SOL.

Cool explanations.

 

[Carlyle]

The 460 it made home. I will try it in the morning, time permitting. At first glance all I can say is "Professionally Done." The saw looks better than in the pictures(nice job on the muffler mod.) I will say the operating sound is more enjoyable than others I have. My 361 almost drives me crazy for how loud it is(not a TW mod.) Full report to come later.

Carlyle

 

[timberwolf]

Here is a little of the port work on the 660.

Just washed the jug out so there are some drops of water in places that look odd.

 

[Metals406]

Here is a little of the port work on the 660.

Just washed the jug out so there are some drops of water in places that look odd.

Brian, that exhaust side looks really clean!

 

[timberwolf]

Thanks, it's pretty good, but I left some plating in the top so a tiny bit of a rough spot there. But I wanted to lower, yes lower the exhaust port as much as I could and keeping the plated port edge in the top center of the port is a bonus.

 

[Metals406]

Thanks, it's pretty good, but I left some plating in the top so a tiny bit of a rough spot there. But I wanted to lower, yes lower the exhaust port as much as I could and keeping the plated port edge in the top center of the port is a bonus.

What are you trying to gain by lowering the exhaust? Are you gonna free port it a little at TDC?

 

[timberwolf]

Stock timing is too high. I know that sounds stupid, but 181 deg is too high for what I want. I'm not lowering the bottom of the port more than what I drop the jug, should not be free porting.

 

[Metals406]

Stock timing is too high. I know that sounds stupid, but 181 deg is too high for what I want. I'm not lowering the bottom of the port more than what I drop the jug, should not be free porting.

How many degrees can you gain before free porting?

 

[timberwolf]

Problem is not free porting on 660, it running out of good bore surface to run the rings on. Even if I can get back 4 or 5 degs it will help with the torque and compression.

Stihl sort of forgot to plate and hone the top .125 of the bore. It's a lightly large diamiter up there so would be easy to hook the top ring and pull the crown edge off the piston.

 

[Metals406]

Problem is not free porting on 660, it running out of good bore surface to run the rings on. Even if I can get back 4 or 5 degs it will help with the torque and compression.

Stihl sort of forgot to plate and hone the top .125 of the bore. It's a lightly large diamiter up there so would be easy to hook the top ring and pull the crown edge off the piston.

Wonder if the lack of plating on the top has to do with the way their jigs are set while plating?

What squish are you shooting for?

 

[Crofter]

It is difficult to hone a dead end cylinder to size when you try to do it right up tight into a square intersection. Much easier if you cut a recess at slightly larger than finished diameter like is done in that bore. Seems like a quick and dirty cost saver on manufacturing. That would be more expected on aftermarket than on stock Stihl jugs.

Really I guess it would not be a problem if you were going to run it stock but it what you can do in the way of lowering the jug if that is part of the game plan.

 

[timberwolf]

I want to get squish between .022 and .025. Hopefully will finish this saw up later this week and test it out on the weekend.

 

[timberwolf]

Few more pics, cleaned a little in the carb and a lot inside the muffler.

Just need to weld the deflector on, set the squish, bolt it together and it's ready to run.

 

[Jacob J.]

Stihl sort of forgot to plate and hone the top .125 of the bore. It's a lightly large diamiter up there so would be easy to hook the top ring and pull the crown edge off the piston.

I ran into the same problem on a new 359 cylinder last year. The last .100" or so bulged outward and caught the piston. The saw initially failed and the ring was stuck, so the dealer that had it traded it to me. I had a machinist friend knock the bulge off and I was able to make it into a decent runner.

 

[timberwolf]

I wish this was a case of the bore being squeezed a little at the top, could fix that, but it's cut too big at the top, not much fix for that.


Anyway here are a couple more. Welding the deflector on the muffler and then the finnished muffler.

 

[Jacob J.]

I really like how you're working over your mufflers these days and the work you did on the carb is exceptional. I see a lot of evolution in the way you're shaping the venturi over some you did in the early days.

 

[Metals406]

Few more pics, cleaned a little in the carb and a lot inside the muffler.

Just need to weld the deflector on, set the squish, bolt it together and it's ready to run.

I'd like to see more on what exactly you did to the carb and why... If you have time.

I wish this was a case of the bore being squeezed a little at the top, could fix that, but it's cut too big at the top, not much fix for that.


Anyway here are a couple more. Welding the deflector on the muffler and then the finished muffler.

Brian, are you using a red banded tungsten? Have you tried orange or gold band?