Little work done lately, tore into the new Command-
Then in preparation for the larger displacement I knew some carb work would be in order. Pleasant suprise here is that even though the Walbro carbs on the K series have made us all real cool to the idea of fixed jet carbs, well the Keihin carbs on the Commands (single barrel version at least) use the same jets as in the Keihin CV (or CVK) carburetors. So if you want to jump up a jet size for adjustment, it just takes getting a new main jet from your local Honda or Kawasaki dealer. Most Command single-barrels come with #150 jets, mine happened to have a #175 jet. I'll probably start with a jet in the 185-195 range to start tuning.
Kohler notes that "only with engineering approval" can the smaller 1.1" OD pipe be used on engines larger than the 624cc Command; all others require 1.25" OD pipe. So I went with 1.38" OD pipe. Turns out this is a little bit of a bear to, even with tight mandrel bends. Hindsight being 20/20 I should have started out just building new, as the old rusty/carboned steel is a bear to weld.
Not wanting the annoying pop of a straight-through design, and not having room to adequately make chambers that would let the engine breathe; I'm attempting to emulate a "Hushpower" muffler with a pair of cone diffusers and a perforated chamber with stainless packing. The outlet went from 1.1" OD material to 2" OD material. Stay tuned for hopefully a running engine with new muffler post-weekend.
OH... and I'll preemptively answer- no I wouldn't do it this way again had the chance.
I'd probably use two Kohler 2416405S stub manifolds, a couple of 1.375" OD mandrel bend 90 degree elbows, a pair of gravely mufflers, and come out the bottom of the grille "982 style". It would be more $ than what I spent, but much more "bolt together".
Wyatt: Good info on the jetting, exhaust seems like a major pain. Could a muffler be used on each port to good effect? I used that tactic on the 16 HP twin cylinder B&S as found in a 582. Just wondering. I know I certainly couldn't fabricate a muffler like yours, whether I started from scratch or modified existing parts.
Of course the dual muffler setup is a "straight through" design, which you say you wish to avoid. By-the-way, the "adapters" for the dual B&S setup cost more than the mufflers themselves.
Thanks for posting your progress, your craftsmanship is amazing and a joy to witness.
Hmmm... for some reason I can't post the ePay link to the tach's auction, but it's about the cheapest ApexMeter chrome bezel there is to offer. Its sold as a "Electronic Cockpit International 4000 RPM 2 1/16" (52mm) Tachometer,white Chrome". It does ship from India, and I think I might have waited 4 days for it at most. Its only settings are for 4, 6, and 8 cylinder engines as well as can read alternator pulses. I have not had any luck getting the dip switch setting for reading alternator pulses to work on my 782 (I've got the same tach on there, but with a black bezel). Nice benefit for those of us wanting to wire it "clean".... the connector spacing is the same as that for a Packard 56 3-cavity connector as what the Kohler solid state voltage regulator uses.
Since a twin cylinder Command fires each of the two coils once per revolution it has the ability to "act like" a 4-cylinder engine to a tach. The problem is tying the two coils signal together- the Baron Tach Adapter does this. Alternatively you could get by making yourself your own adapter with a couple of zener diodes; but this one is potted well and I can set it up so it plugs into the harness I'm working up.
Finished installing the 7500 BTU cooler on Saturday, just have to wire in the fan. Still have to weld in the grille screen into the tunnel cover and paint.
Drove it around for a bit in the afternoon heat on Sunday and couldn't get the cooler more than warm to the touch. I should be able to get the fan switch to close once I get a plow in the ground behind it.
The funny (not funny) part about having 35-40 ponies to play with now is that the engine doesn't even bog down before you have a nice pair of ruts. We've far exceeded "diesel-esque" torque here.
Well, other than bolting on some minor parts and putting on the pre- reverse safety switch PTO switch, the 2072 re-rebuild is about done. The extra 100cc from Midwest Super Cub really gives the CH730 a lot of torque. The hydro cooler seems to be working better than planned; it doesn't yet get hot enough to trip the cooling fan switch.
The only thing I didn't get installed that I wanted to was a return oil filter, there just isn't room for the filter head and a filter with enough volume to not go into bypass when it's cold out. I think it'll work just fine without it.
I'll try to remember to get a parts list together for the cooler. It's only about $125-$150 in parts and fittings.
Thanks again for the comments. (I'm glad this little project went faster than the Wheatland!)