A legend on the porch: Super 797

[cpr]

I might have to go start one of mine.


Lee

You know you want to . Make sure the neighbors stay awake awhile.

 

[RandyMac]

Good vid, it was a trip watching the rollernose spin, I wonder if you could wirebrush the roller to give it more visual effect.

 

[pioneerguy600]

Good vid, it was a trip watching the rollernose spin, I wonder if you could wirebrush the roller to give it more visual effect.

+1
Paint one half!
Pioneerguy600

 

[cpr]

+1
Paint one half!
Pioneerguy600

Pinstripe spiral

 

[leeha]

Add two feet to the bar, five more feet to the wood and that would be heaven.

Your are correct again Randy.
I just have never seen wood
that big. I'd be in heaven to.


Lee

 

[pioneerguy600]

Pinstripe spiral

Any type of design painted on makes them stand out when spinning.
Pioneerguy600

 

[ric5141]

Great saw. The video is great. Would like to see it eating some bigger wood though......

 

[cpr]

Great saw. The video is great. Would like to see it eating some bigger wood though......

Wish I could, but I simply don't have anything here. I don't get big logs here at the house because I use it all for heat in the OWB. Anything I have to split is wasting my time and another piece of equipment I would need and don't have.

Memorial Day weekend we're heading up to the hunt camp, I'm certain I can find something more substantial to chew on there. May have to take the saw with me.

 

[MOE]

I got a little time while my lasagna is cooking, so here goes:

The 797 engine was birthed from the 101b yes, but the timing is not quite the same but close to a 101b. If you look at the piston, you'll see it's identical to that in the 101b. Later pistons from other 101 motors can't be easily interchanged without changing the rod as well, since there were minor variations in the crown height of the piston(s). There's a 101 piston with windows that's timed for the boost port blocks that works well in the 797 with the corresponding rod. There's a rod that's proprietary to the 101b, 101d, and 101AA that can be used in the 797 if you have the matching piston.

The 797 is part of the family of "Super Series" engines which include some of the kart engines and saw engines. The 797 blocks have the removable boost port "window" which later became boost ports actually cast into the block, seen on later kart engines and 125 saw motors. The 797 block is not a third-port block like the Mc20 kart engine or D44 saw motor.

Main 797 features: removable boost port window, bridged exhaust, hemispherical combustion chamber, horizontal-mounted coil, DSP-style compression release, right-hand start, moderately aggressive intake and transfer timing, same stuffer as stock 101b motor (w/cut-out for pulse oiling), crank w/bolt-on weights, and kart-mount style exhaust. The 797 Super would have the updated main bearings, different carb (usually SDC?), thin-ring piston.

The CP-125 block has the cast boost ports, slightly smaller combustion chamber, bridged exhaust, less aggressive intake and transfer timing, horizontal-mount coil, kart-mount style exhaust, single-reed intake manifold, and straight compression release. The piston in the CP motors should have cut-outs for the boost ports and came in both thin and thick-ring. The CP rod would use the 1/2" wrist pin with needle rollers in the piston rather than in the rod. The CP blocks are all steel sleeve blocks as are the 797s.

The SP-125 block has the large oval-shaped exhaust port (longest blow-down time of any of the saw blocks) w/different exhaust mounting, larger combustion chamber, lower intake and transfer timing, dual-reed intake manifold, diagonal-mounted ignition, and "hockey-puck" piston w/no cut-outs for boost ports. The rod in the SP motors uses a 9/16" wrist pin with needle bearings in the rod rather than in the piston. The SP pistons were usually thin-ring. The SP block came in both steel sleeve and chrome-lined bore. The SPs used the straight compression release and the funky squared off muffler with its own proprietary cover. These are not compatible on the Cp and 797 blocks. Cranks on the SPs had the welded-on weights.

How does the SP125C differ from these?

 

[weimedog]

I got a little time while my lasagna is cooking, so here goes:

The 797 engine was birthed from the 101b yes, but the timing is not quite the same but close to a 101b. If you look at the piston, you'll see it's identical to that in the 101b. Later pistons from other 101 motors can't be easily interchanged without changing the rod as well, since there were minor variations in the crown height of the piston(s). There's a 101 piston with windows that's timed for the boost port blocks that works well in the 797 with the corresponding rod. There's a rod that's proprietary to the 101b, 101d, and 101AA that can be used in the 797 if you have the matching piston.

The 797 is part of the family of "Super Series" engines which include some of the kart engines and saw engines. The 797 blocks have the removable boost port "window" which later became boost ports actually cast into the block, seen on later kart engines and 125 saw motors. The 797 block is not a third-port block like the Mc20 kart engine or D44 saw motor.

Main 797 features: removable boost port window, bridged exhaust, hemispherical combustion chamber, horizontal-mounted coil, DSP-style compression release, right-hand start, moderately aggressive intake and transfer timing, same stuffer as stock 101b motor (w/cut-out for pulse oiling), crank w/bolt-on weights, and kart-mount style exhaust. The 797 Super would have the updated main bearings, different carb (usually SDC?), thin-ring piston.

The CP-125 block has the cast boost ports, slightly smaller combustion chamber, bridged exhaust, less aggressive intake and transfer timing, horizontal-mount coil, kart-mount style exhaust, single-reed intake manifold, and straight compression release. The piston in the CP motors should have cut-outs for the boost ports and came in both thin and thick-ring. The CP rod would use the 1/2" wrist pin with needle rollers in the piston rather than in the rod. The CP blocks are all steel sleeve blocks as are the 797s.

The SP-125 block has the large oval-shaped exhaust port (longest blow-down time of any of the saw blocks) w/different exhaust mounting, larger combustion chamber, lower intake and transfer timing, dual-reed intake manifold, diagonal-mounted ignition, and "hockey-puck" piston w/no cut-outs for boost ports. The rod in the SP motors uses a 9/16" wrist pin with needle bearings in the rod rather than in the piston. The SP pistons were usually thin-ring. The SP block came in both steel sleeve and chrome-lined bore. The SPs used the straight compression release and the funky squared off muffler with its own proprietary cover. These are not compatible on the Cp and 797 blocks. Cranks on the SPs had the welded-on weights.

Damn..that's a lot of info! I had one once (a 797) ..it was a great old saw, milled a lot of lumber with that old monster! Had "easy" power. Never really got hot even when milling ...It lived on 100LL and Mobil 1 MX 2T at 32:1. It was retired for big J-reds. For milling? I'm not yet convinced they do any better. Just newer. Going to try and build a 2094 to do what the old 797 did. (Those J-reds are Nice saws and better for everything else!)

 

[cpr]

JJ gave us a lot to chew on didn't he. I have confirmed that the Super is making 125psi... weak. So it needs at least rings. I figure while I'm in there, I may as well put in that window port piston and rod while I'm at it if I can find one. I won't have time to tear this thing down for a while, though. Summers are extremely busy for me at work and on the pulling circuit to attempt anything beyond piddling saw tinkering.

 

[little possum]

Summers are extremely busy for me at work and on the pulling circuit to attempt anything beyond piddling saw tinkering.

Coming down towards NC anytime?

 

[cpr]

I wish, but they keep me running pretty good here in MI.