Re-engine project Toro Wheehorse 268H, V-Twin Kohler to Briggs

[92saturnsl2]

Have a 2000 New Holland LS45 riding mower (Toro Wheelhorse 268H rebadge) I put away a couple years ago, the old Kohler V-twin was shot, needs a new engine. The mower condition is such that it's worth getting going again.

Went with a Briggs; decent deal which became even better after adding coupon codes.

https://www.acmetools.com/briggs-an...n-crankshaft-44t977-0009-g1/400409000142.html

It has the correct mounting bolt pattern & shaft size which will connect w/ mower pulleys and PTO no problem. The big question mark is exhaust and electrical. Has anyone performed this type of swap between V-twin engine manufacturers? I have a hunch the old Kohler muffler won't be a direct fit and that I'm in for some electrical work. I have fabrication skills, so I doubt there's anything insurmountable.

Any input from those that have done a swap to a different manufacturer would be appreciated.

 

[oldcodger]

How is the throttle linkage going to make up?

 

[92saturnsl2]

How is the throttle linkage going to make up?

Same as the last one-- Pull a knob up and down, moves cable which in turn moves throttle. Briggs is single control throttle/choke which will be a PIA. Throttle placement / engine dimensions are very similar, that's the least of my worries.

I'm more concerned with exhaust / electrical.

 

[Elkins45]

Same as the last one-- Pull a knob up and down, moves cable which in turn moves throttle. Briggs is single control throttle/choke which will be a PIA. Throttle placement / engine dimensions are very similar, that's the least of my worries.

I'm more concerned with exhaust / electrical.

You can unlink the choke from the throttle and use separate cables IIRC.

 

[Opelman]

Shouldn't be too hard to figure out since you have the old and new wiring harness' there. Map out which pin on the chassis side goes where and go from there. I just did that on a machine removing a grenaded Yamaha MX 825 EFI and replacing it with a carbureted Vanguard. We sourced the connectors for each side and made a short adapter harness.

 

[Opelman]

Shouldn't be too hard to figure out since you have the old and new wiring harness' there. Map out which pin on the chassis side goes where and go from there. I just did that on a machine removing a grenaded Yamaha MX 825 EFI and replacing it with a carbureted Vanguard. We sourced the connectors for each side and made a short adapter harness.

 

[chemman]

Look at the Toro website for owner's manuals (often contains an electrical schematic) for the equivalent Toro models (one with a B&S engine and one with a Kohler engine). I do know that I have found Toro factory service manuals online for lots of their models that came with engine choices and they contained the appropriate schematics as well.

Good Luck!

 

[92saturnsl2]

New engine arrived. From what I can tell, three wires is all this engine needs to run. One wire is jumped to another position at the connector, which looks nothing like the mower connector. At the voltage regulator, one of the red wires has a quick connect which suggests it may be needed in some applications. I have some work to do; looking up the mower wiring diagram / schematic and figuring out how to adapt the throttle cable. First task is washing the mower of the 1/2" thick oil/grimy mess the old engine left behind.

If first impressions are worth anything, this engine looks vastly better constructed than the Kawasaki FR730V that's used on the zero turn I purchased last year. Metal cooling fin shrouds and fan cover, 2-stage air filter and included oil cooler immediately stood out.

Will update on my progress which may be slow. Goal is to get the mower fully functional by spring.

 

[meep]

Nice looking engine. Agree - if you can trace the functions of the engine controls electrical it will most likely map one to one.

Exhaust may require some creativity. Do they still allow threaded pipe?

 

[92saturnsl2]

Nice looking engine. Agree - if you can trace the functions of the engine controls electrical it will most likely map one to one.

Exhaust may require some creativity. Do they still allow threaded pipe?

Found the wiring diagram for the mower, doesn't look too complicated. I'll have to fasten the green wire to ground as the new engine doesn't have an oil pressure sensor. Red is obviously 12V+, blue to the new starter solenoid (not equipped w/ new engine), violet appears to power the fuel shut-off solenoid from the key switch, but white "MAG" has me scratching my head. It's a ground wire interrupted by a kill relay on the mower and shows it going to "ignition modules".

How it needs to be connected to the Briggs is still a mystery to me, as there's only black, red and grey to connect to.

 

[meep]

The way these engines shut down, all of the ones I’ve seen, is 2. One is the fuel solenoid. It gets power to run. The other is to ground the wire coming off the magneto. To run, the wire floats. To turn off, it gets shorted to ground. That may be “mag,” for magneto.

This would be different from a fuel injected engine which needs power to run.

It sounds like your new starter has an independent solenoid circuit, and the alternator as well? These usually go through a very basic regulator - if it spins it sends, and the regulator then converts to DC and limits the voltage output.

 

[92saturnsl2]

The way these engines shut down, all of the ones I’ve seen, is 2. One is the fuel solenoid. It gets power to run. The other is to ground the wire coming off the magneto. To run, the wire floats. To turn off, it gets shorted to ground. That may be “mag,” for magneto.

This would be different from a fuel injected engine which needs power to run.

It sounds like your new starter has an independent solenoid circuit, and the alternator as well? These usually go through a very basic regulator - if it spins it sends, and the regulator then converts to DC and limits the voltage output.

You'd be right, I think I have this figured out after some google searching on Briggs & Stratton wire colors.

The violet wire from my mower (enabled by keyswitch) would go to GREY on the B&S engine to activate the fuel solenoid.

White wire on mower is essentially the kill wire (fed through various relays / switches); all it does is provide ground to the black wire on the Briggs engine which disables ignition.

The red wire is 12V+ output from the engine charging system, which looks to be pretty simple on this Briggs. There's a voltage regulator mounted to the engine which has two yellow and one red wire. I think the yellow is A/C coming in and presumably it rectifies it and there's +12V coming from the red wire.

The Briggs starter has no solenoid, so I'll have to mount one and wire that in myself. Blue wire coming from mower pulls the start solenoid closed.

Am I missing anything?

 

[Opelman]

You got it.

 

[92saturnsl2]

Progress! The engine fits just fine except I'm going to have to cut the hood and install a scoop to clear the tall air "cyclonic" filter present on this Briggs engine. Hood won't clear it.

Electrical seems easy enough, need to find a 6-pin connector that will mate with engine harness so I can do splicing without voiding warranty on the engine.

The old muffler (Kohler) seems to mate *almost* exactly how the Briggs is configured. The flanges are clocked in the same direction but looks like I need to spread the two tubes apart some.

 

[Opelman]

Looking good. Did you go up in horsepower? Glad to see you saving the tractor.

 

[wag123]

The exhaust is going to be a problem and this is something you need to get right.

 

[92saturnsl2]

The exhaust is going to be a problem and this is something you need to get right.

How so, care to elaborate?

 

[92saturnsl2]

Looking good. Did you go up in horsepower? Glad to see you saving the tractor.

According to tractordata.com (pretty reliable) the mower should have had a 624cc Kohler V-twin rated at 18hp when it was built.

When I purchased it in 2018-ish, it seems someone had transplanted a Kohler 23hp (~700 cc) V-twin in it. The stickers were faded so I couldn't pinpoint a serial number or date when the motor was installed. I was an idiot for buying the mower, the engine burned oil terribly from the moment I got it and fouled spark plugs constantly. Aside from the engine, the mower is fantastic.

The new 25hp Briggs engine is similar in size (~720cc) to the non-factory 23HP Kohler that was in it. So if comparing to the OEM engine, I'd certainly say it's a jump in horsepower. Extra power wasn't my intention, best bang for the buck won.

 

[meep]

This might get you close. I typed in “6 pin molex” and found this:

https://a.co/d/4OubEpv

 

[92saturnsl2]

The exhaust is going to be a problem and this is something you need to get right.

Exhaust was not a problem at all. I cut the two tubes off the muffler, bolted them to engine then compared where they met with the muffler afterwards; not far off. I had to tweak the tubes a little which is easy to do. Cut 3/4 of the way through, bend it where you want it, then weld it all back together. Works better than bending which crushes the pipe, not sure it's even possible to bend thin wall pipe that's been through a thousand heat cycles.