C100 gets a new engine

[C100_8 25]

I’m changing the engine on my c100 due to the original being very tired. I happed to find a K321which is now mounted but now I find that the drive pulley is larger than on the 10hp engine so the drive belt won’t fit. Is this common for the 14hp engines?  Should I use the pulley from the original engine or get a longer belt?  

[ebinmaine 73,484]

Use the original. 

Be very cautious of how it's removed and replaced. 

The correct pulling method is a game changer.  

 

 

 

 

 

[WHX?? 52,144]

Kev you forgot to mention use some schlip n lube and clean the crank end first. 

 

Might be the 14 ran a hydro thus the bigger pulley. 

[ebinmaine 73,484]

3 minutes ago, WHX?? said:

Might be the 14 ran a hydro thus the bigger pulley

 

Agreed 

[oliver2-44 10,827]

If you want you Horse to be a little faster, you can use the larger (hydro) pulley and buy a longer belt.

[Ed Kennell 42,444]

If you use the larger pulley, you'll have to modify he belt guard and possibly the foot rest.

[8ntruck 7,989]

  Probably will need to modify the belt support on the belt guard as well if you stay with the larger pully.

Edited August 31 by 8ntruck

[C100_8 25]

Thanks for the information everyone. I’ll swap the pulleys today. 

[C100_8 25]

Good news. Pulley swap went well and the tractor moves under its own power again. 
The bad news is the charging system is giving trouble. The charging system worked fine on the old engine. The new engine has about 25-26 vac at idle so that seems right. I’ve cleaned the rectifier ground. Confirmed it has good continuity to ground. Engine has good continuity to ground. Battery power is at the rectifier as well. The new engine has a three pin plug and when I connect it the generator grumbles a little and the wires get hot. The battery voltage also dips when it’s plugged in so obviously something isn’t right. Any ideas?  

[pfrederi 18,786]

Not sure you what you mean "generator grumbles"  Is the noise in the engine or the regulator.  Two wires in the engine plug should be the same color (AC voltage)  does the third wire go to the small + on the coil???

 

Did the old 10hp engine have a 10 or 15 amp charging system??  What does the new engine have?

[C100_8 25]

I think I found the issue. I believe the new engine has a diode on one of the lines as shown in the diagram below. Can I just bypass the rectifier completely and run the diode line directly to the switch as shown. Does anyone know if there is a different switch for this kind of charging system?  

[953 nut 60,826]

You need to know the SPEC # and Serial number of the replacement engine, look it up to find out what it came from and use the wiring diagram / ignition switch information from that.

[ebinmaine 73,484]

16 minutes ago, 953 nut said:

You need to know the SPEC # and Serial number of the replacement engine, look it up to find out what it came from and use the wiring diagram / ignition switch information from that.

 

Seconded

[953 nut 60,826]

On 8/31/2025 at 5:11 PM, C100_8 said:

The charging system worked fine on the old engine.

One option would be to use the flywheel and stator from your old engine on the replacement engine and then there wouldn't be any wiring changes needed

[Retired Wrencher 5,944]

On 8/30/2025 at 8:25 PM, ebinmaine said:

Use the original. 

Be very cautious of how it's removed and replaced. 

The correct pulling method is a game changer.  

 

 

 

 

 

Eric that is how I remove them. Works every time.