50cc CHAIN shoot out - 3 Bars, 3 Chains, 5 Sprockets, and 1 Saw.

Don't worry about finding PM. If you can, great. But you gotta try some of this PS3.

 

Gonna need a picture to explain this one but it's pretty much the same reason you really can't use Picco on a standard 3/8" bar.

Remember, pitch is the distance between any 3 rivets divided by two. So even with the same pitch, there are other factors that affect fit. Like the shape of the drivers. The narrower, shallow drive link on Picco chain leaves a good amount of play in the sprocket fit on a standard 3/8" pitch sprocket. This will drive the chain ok at first but it will also create some funky wear patterns.

Here is the chain, 3/8P on top of standard 3/8:



Picco on its proper bar/sprocket:


Notice how tightly the chain fits around the teeth of the sprocket, no gaps.

And here it is on the Std 3/8" bar:


Notice the gaps I between the sprocket teeth and the drive links.

Picco bar has a 10 tooth nose sprocket vs 11 on the Std 3/8" bar. Also note the short, wide teeth on the Picco sprocket vs the narrow, tall teeth on the Std 3/8" sprocket.

 

If there is yellow label PS, I have not seen it yet either on the shelf or in the chain catalog. Would be my chain of choice on a LOT of sub-50cc saws if such a critter exists.

PM was excellent chain, this stuff is out-frickin-standing.

 

What HedgeRow said. But a square-filed loop of PS3 would be siiiiiiick.

 

So, how about a little more info about the bars....



Top to bottom: .325 .063", 3/8" .050, and the 3/8" Picco .050" bar. All were 16" bars and 3003 mount.







While the .325" and 3/8" Std bars were identical in shape, the Picco bar is more slender with a smaller nose radius and a slightly modified tail shape.







The Picco bar is also just a bit longer than the other two. But not by much!

 

Does grinding the top plates to 10deg first help? (And then filing square)

 

Boog, that's a 3005 (Mini) mount bar that won't fit your 024. AFAIK the 16" bar I have is the only bar available in 3003 mount AND 3/8"P.

 

I'm not done beating this horse......

The sprocket line-up: (in the order that I ran them)



Since these were the most interesting performers, I'll focus on these 3.



The .325-8 and the 3/8"P-7 were nearly identical in size but not performance. The 3/8"-7 is close but just a tad smaller diameter than either of the other two.



Since the 3/8" sprocket is slightly smaller and the 3/8" setup were the slowest average cut times, one can assume the load was a bit much for the power available.