OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Walk Behind Lawn Mower Frames Question On Scott Bonnar Cylinder Mowers Scott Bonnar identification

Hi everyone,

We recently given this mower, we would like to restore it, but having difficulties finding information on it. The person that gave it to us said it was a crank start.

Does anyone have any information on this?

Thanks
Jen and Clay

Picture of the plate

Jen/Clay, that is a Briggs and Stratton engine on a Scott Bonnar Model 45. The problem is that somewhere along the way, somebody has removed the cooling air cowl, to which the rewind starter was attached, and cobbled a crank starter. This was a very bad idea, since the cooling fan on the flywheel can only operate effectively when the cowl is attached. The cylinder head currently has almost no cooling air flow, and will overheat whenever the engine is run under load.

Here is approximately what your engine looked like when it was complete:

Here is your engine from much the same viewing angle:


I do not know what other crazy things have been done to the engine - perhaps none, if you are lucky. However you need to obtain an old cowl and attach it. That will make your engine start with a normal recoil starter, and cool itself properly as well.

The complete engine I have shown is a Briggs and Stratton 60102, an engine model used on the 14" cut SB Model 45. The 17" model used an 80102, which was advertised as 3 hp rather than the 60102's 2 hp. The difference between the engines was cubic capacity, due to the 80102 having a different crankshaft giving a longer stroke. Generally the engines were otherwise the same, and used the same cylinder/crankcase and cooling air cowl.

Your mower is an early-production SB45, with a single deck. This means it is both a more durable, and more collectible, mower than the later ones with twin-rails instead of a single deck.

I'm sure our reel mower guru and Scott Bonnar 45 enthusiast, Deejay, will join this thread and ask for some pictures to help him assess the condition your machine is in. Meanwhile, please don't use it until the engine has been completed: it should not be run without a cowl.

Hi Grumpy,

Thank you so much, any little piece of information is valuable so we can start looking into finding what we need. I've attached some more photos too. We could find information about similar looking mowers but nothing about this specific one.

Cheers.

Hi,

This is so interesting, I love this site and the knowledge.

I just found this thread, is Finbar's the same as ours? so the information would be the same for ours?

https://www.outdoorking-forum.com.au/forum/ubbthreads.php?ubb=showflat&Number=48700#Post48700

cheers

Yes, you have a very early SB45 14" with a Briggs and Stratton engine, and so does Finbar. Hence your mower would have been much the same as his when it left the factory. There are some issues of interest to collectors involved. Early SB45 14" models seemed to usually have Kirby-Lauson engines rather than Briggs, and it isn't clear (at least to me) when the changeover happened: Scott Bonnar may have been stuck with excess stock of the (relatively unattractive) Kirby-Lauson, and may have had to "build them out" since they could not be returned to Kirby. Normally your mower would have been a help to us in understanding what happened, since Briggs engines are each stamped with a precise date of manufacture. Unfortunately the date is on the (missing) cooling cowl, so we aren't likely to ever find it out, unless the person who gave you the mower kept the cowl after he/she removed it.

If you get a moment, please take a picture of the chain case cover from the left side of the mower (when facing forward from the operator's position). Then remove the cover and photograph the chains and sprockets, from a position close to each sprocket and in line with the axis of that sprocket's shaft. Deejay will look at the shape of each sprocket's teeth, and assess how worn they are. He will also comment on the condition of the mower's cutting reel, and if he can see it, the stationary bedknife that the reel's blades cut the grass against. A view of the mower from just a little further away than the last one you posted would also help him get a good look at the height adjustment knob on the left side of the front roller.

Just for preliminary information, your mower is looking very promising indeed, as a restoration project.

Hi Jen79, and a warm welcome to the forum. It's always nice to have another Scott Bonnar owner on board.
grumpy has given you excellent advice, it is the early model 45, solid engine deck, manufactured in the late sixties, early 70's.

The cylinder reel has plenty of meat on it, but could do with a sharpen, I cant' see what the bottom (bedknife) blade looks like from that pic....but I would hazard a guess that it would need to be re-ground as well. I would also recommend replacing the reel bearings at this time if at all in doubt of their serviceability, as they are critical to the successful set-up of the reel to bedknife clearance.
I would like to see a pic of the chain case, particularly where the chains do not cover the sprockets so I can access for wear....
Good hunting for an air-cowl for the Briggs....
I agree with grumpy.....a good restoration project!
Once again, Jen70, to OutdoorKing.

more pics, looking forward to getting a start, we were considering selling, but we are restoring now given the information that we have, its just too interesting to part with now.

Hi Jen, all the sprockets are still serviceable, though the small (top) one and the double cylinder reel sprockets will need replacing further down the track. Replacement of the primary and secondary chains would also be recommended at this time.

I am so glad you are keeping your machine...once it is up and running sweetly, it will give you hours of mowing pleasure and a fine striped lawn.

well look at what I just found.

http://www.ebay.com.au/itm/Scott-Bo...owers&hash=item3a9327c76b&_uhb=1

the briggs and stratton were 1968.

Hi Jen79,
I have seen that brochure before and the Briggs and Stratton was fitted first to the 14" machines, and the year was 1968....that was when the Model 45 range of mowers were first introduced to the market. The Kirby Lauson (Tecumseh) engines were fitted to the 17 & 20" machines, before finally settling on the Briggs engines in the mid-seventies.

The closest date we can arrive at for a Briggs engined Scotty is by the Model, Type and Code, which is stamped into the cooling air cowling of the Briggs. The code gives us the date of manufacture of the engine, and allowing for freight from the USA gives us the year of manufacture of the Scotty at Thebarton in Sth Aust.

Hi Deejay,

We are going to sell this mower, what would you think its worth? in it's current condition. Motor condition unknown, as I haven't started it. Considering it has the missing cowl I would suspect..not a great deal?

Cheers Jen

Hi Jen,
Conversations of this nature are done by private messages, Jen; Look for a flashing envelope in the toolbar above...Just click on the envelope...