OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Walk Behind Lawn Mower Frames Question On Scott Bonnar Cylinder Mowers Advice needed on SB 45

Hi all
Just got myself a sb 45 to restore as a hobby...Its got the Kirby 3 hp engine which i have managed to get running but is leaking fuel from under the carb..(any ideas)can you get the parts?.The frame has also been welded at the front engine mount.Prob not the best job..Also one of the drive chains is broken..Am i wasting my time and should i buy a better one or it all repairable .Does anyone know what the model/nos mean
Many thanks
Alan

Hi Pikey, welcome to Outdoorking. I see that your SB45 has lots of meat on the reel (blade cylinder) but the chain sprockets are somewhat worn (though they still have life in them). These are usually the two most expensive potential problem areas, aside from the base engine, so your mower seems a worthwhile candidate for restoration. I'll leave it to Deejay, our reel mower guy, to discuss details with you and help you reach a decision on restoration. With regard to the Kirby Lauson engine, they have a water drain button in the bottom of the carburetor float bowl, and it has a tendency to drip fuel in advanced old age. You will need to remove the float bowl and look closely at the sealing washer that is built into the drain mechanism. The repair process may be a bit fiddly, but people do it successfully. I personally regard the water drain as not especially useful - you can drain the water by just removing the float bowl and cleaning it out - but if you plan a full restoration, it is best to repair the machine in detail rather than take shortcuts.

Hi Alan, and a warm welcome to the forum. It's always nice to welcome a Scott Bonnar Model 45 owner on board.

I have had a good look at the pics and thanks for posting them. Here is what I have found:
(1) Your machine is suffering from quite a few 'tenants improvements'. That is to say a few non-standard parts have been added.....but all can be remedied.
(2) I believe that your Scotty is a good candidate for a full restoration, and once completed will give you hours of mowing pleasure.
(3) You will have to purchase a few new parts to complete it, but just remember that a machine was $1850.00 when new, so that any purchases you make will be money well spent.
I can see the primary chain underneath the engine in your pics, that may be re-usable with the addition of a couple of removable chain links for now, until you decide to replace the cutter sprocket and the primary small engine shaft sprocket.
A new front roller cylinder and 2 end-caps is needed as yours has suffered from ' tenants improvements' and now too short to do its job properly.
A castellated nut with a dodgy nail has been fitted to the primary cutter sprocket....this can be replaced by the correct original nut.....as can the castellated nut fitted to the outside of the lower bearing cap.

A regrind of the bedknife blade and cylinder reel will be required, and new reel bearings as well. This will ensure the correct reel to bedknife clearance, and a great cut.
The engine should be removed from the machine and the front engine deck rail crack attended to before re-painting. We can advise you for that.
The red plastic plug for the chain case cover (where the hole is) should be replaced as should the small plug for the height adjuster handle. (this keeps water out)

As to your question on the 2 SB ID plates, the top one is the mower serial number, the lower is the model number, which designates that your machine is a 17" cut. That info was later combined in the one plate.

Alan, you will not be wasting your time, this machine will come up a treat with some TLC.
Once again, to OutdoorKing.

Hi Deejay and Grumpy

Many thanks for your replies...

I will now attempt a restoration after your advice.

I'll put some pictures on as i go along

Thanks again

Alan

What year roughly would this mower be from and were they that expensive at that time?

Alan

Hi Alan, the Scott Bonnar Model 45 was first introduced in 1968 and came in 3 cutting widths; 14", 17" and the 20" (which also sported an 8 blade cylinder reel).

These machines all had a solid engine deck; the 14" powered by a 2.5HP Briggs and Stratton, the 17" had the HK25 2.5HP Kirby-Tecumseh (later the HK30 3 HP) and the 20" always had the HK30 Kirby-Tecumseh engine fitted.

Your machine has the twin rail engine deck and the Kirby-Tecumseh engine and was produced roughly between 1973-74.
As for the price, these machines were always expensive, the cheapest Scotty, the Bonmow, was 75 pounds 15 shillings and sixpence in 1957, which was a lot of money back then. The last Rover 45 sold was almost $1900 a few years ago.