OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Walk Behind Lawn Mower Frames Question On Scott Bonnar Cylinder Mowers My 20" is nearly there!

After a long hiatus my 20' 45 is almost there. However I have a question on where a large spring should go as I can't find any reference to it in both the older Scott Bonnar and the Newer Rover 45 parts list.

Here is a pic of the spring and my 45

Hi GregR,

I don't think it belongs to this machine, unless a previous tenant of the machine had it doing something Scott Bonnar never planned on ?

I gather you have left the rear roller intact and not pulled it apart as is the same with the front roller ?

Cheers,
BB

It was a full strip down an respray due to frame fractures. It was stiffened up by welding a 6mm bar underneath.

Hi GregR,

I know what it is, this is why I asked whether you disassembled the rear roller. It is a spacer that goes between the left hand roller bearing and bearing cup. So it's not normally seen as it's hiding inside the bearing cup with the bearing covering it.

Cheers,
BB

That is exactly what it was!
Thanks heaps.

Now for a real question How easy is it to put a GX 120 onto a 45 and how does it compare to the B&S OHV equiv.

Onto a 20 inch series 2 mower ? no issues at all.

Honestly you can't beat a Honda. You can leave them unused for years and just put some fuel into them and pull the starter and it'll fire up instantly, where as a Briggs ??????

Cheers,
BB

I know the GX 120 is considered the gold standard in small engines but I wonder has anyone had experence with the B&S 3.5 I/C ohv which looks to be an Asian design (probably a product of B&S's joint venture with MHI) or probably another Honda knock off

http://www.briggsandstratton.com/lam/en/rider-mower-engines/ic-engines

Hi GregR,

I've just fitted one the Briggs motors straight out of the box that you're talking about and they are very good. Much better than the earlier vertical running piston and what makes them even better is that they can be fitted straight onto a Series one Scotty 45 without fouling on the early shaped handle bar.

Cheers,
BB

I know Mitsubishi did do a good small engine but how good are they compared to the Honda is another issue. What i have been quoted is the 3.5 Briggs with a 3/4 inch shaft new clutch half with counter balance. It's interesting that in the past my unit was re-engined with a Kawasaki FA 130d while a great design for a side valve, parts are just a pain in the a**e to obtain and those that are cost a bomb.

Hi GregR,

The current Briggs engine can be obtained for around a low $269 if you shop around and that's in both 5/8 or 3/4 PTO shaft sizes. When you refer to a counterbalance, do you mean that small half moon piece of plate that fits onto the nut side of the clutch half ?

Cheers,
BB

Yes the half moon piece is what I am talking about.

Looking at the Briggs closely, it looks like its a Mitsubishi GB130 (Probably made in China) with a different Fuel tank and air cleaner assembly. So the design should be ok.

Note the similarities in Bore and Stroke.

https://www.mhi-global.com/products/detail/4_stroke_gasoline_engine.html