OutdoorKing Repair Forum Forums Restoring, Customising and Modifying Reel-Type Mowers Qualcast engine swap

Any one here ever done a Honda gx120 motor on a qualcast super 14? Or on any reel mower? What are the bugs of doing this? New cluch and shaft?

Hi Michael,

So far as "modern" mowers are concerned (those made for standard American engines such as Briggs), the base mounting bolt positions and output shaft positions are normally standardised, so if your original engine was standard, you can fit other standard engines as a simple bolt-on conversion except for one point: output shaft length and diameter. If your mower originally had a British engine however, it may not be made to the standard dimensions. If the output shaft is not in the same place relative to the mounting bolts, you have a fairly substantial job to fit a standard engine such as a GX120.

If you look at the GX120 installation dimension drawings here, you can compare them with your original engine, whatever it is:
http://www.justgenerators.co.uk/pages/Honda_Engines/PDF/979.pdf

Hi Michael_xr8, I have a G100 Honda on my 17" Scott Bonnar Model 45 and am very happy with the conversion.
Can you please post a pic of the current engine and clutch assembly and also how the current engine fixes to the engine deck.

Hi Michael Im just going through the process now.
Gx120 has a 3/4 inch shaft so I had to change my clutch body from 5/8's (On SB Model 45) I also put a new thrust race in and drive shaft bearing. just so everything was in line and true. Drive shaft was fine on SB 45
Havent started it up yet. But its going together ok thus far.
Not sure if that helps

Jamskin, is that a Qualcast super 14 like Michael's you are putting the Honda on? What engine did it have originally?

Hi Grumpy
No I am putting it on a Model 45 Scott Bonnar.
It had a Briggs & Strat originally

Jason

Jason, the small Briggs and Stratton, Lauson/Tecumseh and Honda engines all have the same mounting bolt positions and output shaft positions. That makes them physically interchangeable except for output shaft length and diameter. Some older engine designs do not conform to these standards, and substituting modern engines for them may require new mounting holes in the mounting deck, or a spacer plate with non-aligned upper and lower holes, or something more complicated if the old engine's crankshaft is too low rather than too high.

Hi Grumpy, Jason and Michael, the Qualcast Super 14 uses a Suffolk 4 Stroke engine, from the UK, and may have (from memory) a centrifugal clutch. It is quite a large engine physically and may have a completely different mounting specs than that of the Honda. Here's a pic:

Maybe it will be better to get it going and sell it to a collector?

I think any collector would prefer it with the original engine. Substituting an engine that was never an original equipment item for that mower, has a negative effect on collectibility. If the mower was a rare one (which yours is not) it would be important to make the substitution without drilling any holes or making any kind of modifications, while keeping the original engine stored for later re-installation.

That's exactly what I meant, get it going with the orig engine and sell it. Instead of modifying it to put a Honda on it. I thought it was a pretty Rareish mower I've only seen two.