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2020/10/23 13:28:47
dcolburn

17.5HP Briggs & Stratton in John Deere Riding Mower

Will the 17.5HP B&S from a Yard Machine mower bolt-up OK in a John Deere 105, please?
The label on it reads: 500cc 17.5 gross HP per SAE J1940
The local mechanic said the crankshaft and wiring harness need to match up.
If necessary I can modify the wiring harness.
Thanks!
13 comments Leave a comment
Roy
It will bolt up, the mount pattern is the same, but as your mechanic says the crankshaft diameter and length have to match the old engine. You may have to use the original alternator which is not difficult to change.
2020/10/23 14:24:04
dcolburn
So, I'd need to remove the engine from the Yard Machine mower, then measure the crankshaft diameter and length? Might there be a resource on the Internet that lists crankshaft diameter and length for replacement engines? Thanks!
2020/10/23 15:20:18
dcolburn
I found this to locate the engine ID#
The # was "31C707-0603"
It was, of course, not that simple - also needed the 2-character extension in this case "B2".
And still more ... two different dates ...
591762 CRANKSHAFT -Used After Code Date 12071700
797579 CRANKSHAFT -Used Before Code Date 12071800
I'm guessing the numbers that follow the "B2", which are "0804237A" may be the Date.
Maybe 2008 (08), April (04), day 23 (23)? (Discarding the "7A" for the moment)
The 797579 is no longer available, superceded by 595339 - which runs $70-$100 used, up to $365 new.
So then to look at the John Deere crankshaft ...
BTW: Will a 20HP engine from a John Deere bolt up right in one that has a 17.5HP?
 
2020/10/23 18:47:29
dcolburn
The Briggs & Stratton engine I've been offered is actually 21HP (I just received a photo).
It's labeled as a G4 crankshaft and OHV.
The engine in my John Deere 105 is also labeled G4 crankshaft but not OHV - does it matter?
 
 
 
2020/10/23 19:46:46
Roy
The two crankshafts are different in that the position of the flywheel key was changed, the pto is the same. The J-D is getting up there in years if it has the flathead engine, they are no longer made. Use the muffler from the ohv, the one on the J-D won't fit. You will also likely have to use a longer throttle cable which is not difficult to make.
2020/10/23 20:35:18
dcolburn
Can I use either crankshaft or does some modification need to be made, please? OK re. the muffler and throttle cable. Will the wiring harness be the same?
2020/10/23 21:51:50
Roy
You can use either crankshaft but be sure to include the matching flywheel. The new engine likely has an anti afterfire solenoid on the bottom of the carburetor that will need to be wired to the accessory terminal on the igition switch.  It needs to have power with the switch on so the engine will run.
2020/10/23 23:01:27
dcolburn
Sure appreciate the assist!
The 21HP engine w/muffler is here (nearly 4hr round-trip) and it looks good.
Will bring it to the shop Monday & see how things go.
I'll report back the results ... and any new questions they may raise.
Thanks again!
2020/10/24 15:43:53
dcolburn
Engine has been mounted and is reported (by the shop) as working fine.
Way cool news!
They asked me to locate the part number for the correct choke & throttle cable set.
They said on the old engine it was a single & shorter cable but it's two for this engine.
Thanks!
2020/10/27 19:23:39
Roy
Then you need to find an equipment manufacturer that uses a two cable system that would work on your tractor. Easier to make one up.
2020/10/27 20:42:14
dcolburn
He said they're used on the John Deere model that uses the 21HP OHV engine - I just don't know that model #.
2020/10/27 21:44:18
dcolburn
I think that this is it:
Throttle-Choke-Cable-For-John-Deere-GY20772-Twin-Control-Handles
https://www.ebay.com/itm/...l-Handles/392992094401
 
Or, maybe this (both list the LA125)
https://www.amazon.com/Throttle-Replaces-GY20948-Control-Handles/dp/B07CS5BRHP
2020/10/27 22:31:09
dcolburn
Cable handle and engine all good.
 
Works well - just need to secure the handle better.
 
Thanks for the assist!
2020/11/08 20:34:40

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