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

Hi all, I'm an absolute newbie to the beautiful old masterpieces of lawn mowing magic. I just picked one up this morning from a kerbside rubbish pile.
I'll get some pics and post them a little later..but for the time being can someone help me identify what it is exactly? The Numbers and figures stamped onto the mower and the engine are as follows.

Scott Bonnar 2.5HP 45 ( Petrol Tank) Kirby Tecumseh.(painted yellow)

Mower Serial No: 45 63343
Mower Model No: 450423

Engine: Kirby Tecumseh.
Model No: HK30
Specification N0: H4-5A
Serial No: V10 3503
Spark Plug: KLG FS15M

I've tried to find the engine type but all I keep coming up with is H4-4A...not H4-5A as it is stamped on the engine ID Plate.

Any clues?

It looks complete and I have set myself a goal of restoring it to it's former glory.

Cheers in anticipation.

Gazza

Hey Gazza I'm 54 and nobody calls me an old Fart ! LOL

Honestly I'm not sure what you're asking about as you've got all the info there right in front of you.

Once you post up some photos we'll be able to see what you actually have there. As they say a picture tells a thousand words.

Cheers,
BB.

Hi Bonnar Bloke, yep...my wife calls me an old fart...she's 11 yrs my junior..hehe. I'm 62 to be precise.

I was just wondering about the engine being a H4-5A...not the usual H4-4A I keep getting when I search for it.

Can I assume it is a 20Inch cut mower?

Cheers

Gazza

Hi gazza,

It seems we have similar mowers, mine is 17" Scott bonnar model 45 Kirby powered
Mower no: 45 62352 -so I guess mine is a tad older?
Same model number, same hk30 and spec number.
I would've thought hk30 would be 3hp and hk25 the 2.5hp equivalent?
But the fuel tank states 2.5?
I also asked the question of 4a-5a and 4a-4a - cyberjack replied saying they made some carby changes at some point.
From wat I can see the obvious difference is the larger fuel tank ? From pics I have seen on the forums etc.
The carb may be different but haven't seen the two side by side , so different carb may require more fuel?
I am undergoing a long fix up/ resto.
Anyways I too would like to find more info aswell.

Good luck

Grame

Hi Gazza and Grame,

Yes this has always been a bit of a confusing issue. I was always of the understanding that the HK30 was the 3Hp unit and the 25 the 2.5Hp variant. Most of it is in the governing set up and variants of the carburettor. It much the same scenario as the Briggs and Stratton egines which range between 2Hp and 2.5Hp. They are basically the same components but the governor is slightly different thus giving a bit more power.

Like I mentioned in my previous post, a picture tells a thousand words and sometimes we are all just surmising without the evidence in front of us.

I can't stress enough, Photos Photos Photos

Cheers,
BB.

Ok.....photos it is....just bear with me...lol

Gazza

G'day all

Yes, the 450423 was the 17" and it appeared in the 1974-75 Parts Catalogue



Note how the Engine was given a different designation for cut size.
My best guess is that the jetting or governing changed with
the differing sizes. An obvious difference was the fuel tank size...
More work is needed on that.

----------------------
Jack

The Fogger was a tinkering project I saw on YouTube...dammed thing works like a bought one..lol

Regards
Gazza

Hi Grame...looks like my lovely find is a 17" inch model too...yip yah...here's hoping we can restore them to their former glory.

Cheers

Gazza

Hi Gazza,

It's just amazing how many of these ol' girls are still out there rotting away in sheds unused.
This particular machine probably hasn't been used in over 20 years by the looks of that reel, but what amazes me is that with a good strip back and repaint correctly it can look like it did around 1974 when it came out of a store.

Sadly you didn't get the catcher so I'd go back and demand that they hand it over as that's the most expensive single item on the whole machine.

Can you please explain the "Fogger"

Cheers,
BB.

Hi BB,
Funny you should mention the catcher...I got that too...but didn't photograph it. It needs a bit of repair, but it is nothing I can't fix with some fine MIG welding work.

And that...is the whole idea of me picking it up...a nice meticulous restoration job where I can spend hours in my man cave doing what I like best.

The fogger, well, as you can see the muffler is now located on the end of an extension that I made for $8.00 from Bunnings. The copper tube I had laying in the shed gathering dust. The pump up spray bottle was about $5 and the plastic tubing and brass fittings were in a tin of bits and pieces I have.

The basic idea of it is to pump a mixture of Diesel and Maldison flea and tick wash (I use 25 parts Diesel to 1 part Maldison ) into the copper pipe via a small stainless ball valve that I use to control the flow. It then flows down the pipe which is wrapped around the extension which acts as a pre-heater so the liquid is nice and hot before it goes into the exhaust extension via the "T" where you see the pipe connected to it.

The super heated mixture is then burnt by the hot exhaust gasses and this produces a lovely thick cloud of Mosquito killing fog that penetrates everywhere in the foliage and grass that I treat. The adult mozzies don't die immediately though..it buggers up their nervous system and they die off in a day or two and are unable to breed. If you treat your yard about twice a week at sunrise and sunset ( when the mozzies are most active and the breeze the calmest) you will plunder their population like an atomic bomb.

All you have to do is make sure you have enough pressure pumped up to keep the mixture flowing and Bob"s your Uncle. Hey presto...a cheap home made fogger that cuts your grass as well as kills the mozzies.
Make sure you wear a mouth and nose filter like the Chinese do in Beijing..as inhaling the stuff will more than likely not be too good for your cast iron constitution.

Check out the YouTube video and you'll see where I got the idea from. I have a very small Brass Needle Valve being delivered from the US as the ball valve isn't precise enough to get the mixture running perfectly.

[video][/video]

Enjoy

Gazza

Hi Gazza,

Honestly that is totally absurd. Here in Adelaide your neighbours would be straight onto the council complaining like crazy. If you had a car that was pumping junk out the exhaust like that you'd get an instant defect notice stuck on the windscreen.

BTW do you supply those Michael Jackson face masks to all your neighbours ?

My wife would be totally unimpressed if she had the washing out on the line and that crap was flying over the fence.

Instant Neighbourhood Wars from where I see it.

Great idea, but not in today's world of OH&S

Cheers,
BB.

PS. Glad to see you got the catcher with it as normally that would've been tossed out earlier due to being in the way and it's much lighter to lift up and dispose.

Also I just noticed, isn't that engine 90 degrees out on the way it's mounted on that frame ? normally the spark plug faces forward and the exhaust goes out the side and not straight back onto the operator ???

Cheers,
BB.

BB, plenty of those early Briggs vertical pull motors were turned that way for some reason, never could work it out, and if they were the rear catcher type the inside of the high arch is always coated with black soot, they look terrible

Hi Norm,

Firstly thanks for that, I thought that this might have been the case as I've seen them like this before, but honestly having a muffler blowing stinkin' hot air straight at you isn't pleasant. I've got a stand in Briggs on one of my Scotty's that's just there while the original engine gets a rebore and it has one of those narrow long straight barrel mufflers fitted and with it blowing a bit of smoke it just makes all your clothes stink. Normally they had the fat oval muffler fitted with the screw attached deflector plate to blow the exhaust sideways and away from the person pushing the mower, now that's sensible.

Cheers,
BB.

Ah yes young gwasshopper (said with squinty eyes)...what I have failed to tell you is that I reside on a 8480 square meter block here in idyllic Port Stephens just north of Newcastle. My yard is almost a tropical paradise with hundreds of meters of hedges with trees and shrubbery of an insane variety and amount.

My nearest next door neighbor is hidden behind 20 foot high thick shrubbery that forms a fence on 3 sides of the property. As a matter of fact...they like me enveloping my place in the fog as it means that the excess fog that filters through the shrubs will help relieve their mozzie problem as well.

Cheers

Gazza

Did I hear BB say.."more pics Please"
Your collective assertions as to the state of repair of this marvel will be muchly appreciato.

Cheers

Gazza

Looks like I have solved the problem of what type of air filter it had..note the past tense.."had"...it has 'melted' over the years and has finished up as a rubbery lump in the Carby, where it has totally gummed the interior workings of the beast.

Obviously the lack of maintenance and cleaning has led to the foam air filter slowly dissolving into an almost glutinous mass that has become hard over the years and has actually stopped the choke butterfly from moving and the residual foam has gummed up the fuel bowl and needle and seat.

No wonder the previous owner threw it out..as most of the problems as far as I can see are due to a total lack of plain old 'looking after the bloody thing".

I might buy a new carby and see if that gets the trusty Tecumseh ticking over again.

Cheers
Gazza

G'day OF54,
This is what the foam element for that one looks like - https://www.outdoorking-forum.com.au/engines...lters/kirby-gee-foam-air-filter-gee-273a
Basically a blind ended tube of polyurethane foam. These do tend to turn into sticky gunge with age.

I wouldn't think that the gum in the carby bowl is from the filter - gum from old fuel that's evaporated after standing for years is a very common problem these days.
There are some very effective carburettor cleaners that will soften the gum, but first you must ensure that all rubber and plastic parts are removed from the carby, including a soft tipped needle, or soft seat, if fitted.

Cleaning out the small passages in the carby with stiff wires [oxy torch tip cleaners have their uses] or jet drills can be a fiddly job, but shouldn't be too bad on that one. Unlike some modern Japanese carbies...

Over post quota images moved to this post

Thanks Gadge, my bad..I was under the impression that each pic was not to be more than 4mb in size...I now know better.
Cheers
Gazza

No worries OF54,
Correct, but there's also a 15 pic per post display limit, which isn't mentioned in the 'how to' or help for direct uploads.

Great pics BTW; I'll let our in-house SB aficionado comment on the condition of the bits. The chassis rails under the engine look to be crack-free, and that's the chief achilles heel of the SB45 twin-rail design.

The main limitation with Kirby-made engines these days is very limited parts availability.
Kirby exited small engine manufacture in the 1970's, and Tecumseh Engines closed down in 2008. It can also be difficult to cross-reference Kirby and Tecumseh part numbers.

Hi OF,

My first port of call would be the engine and to see if it was worthwhile salvaging or simply swapping it out for a new power plant which isn't that expensive now a days.

Is there a good amount of compression, pull rope starter and see how much resistance there is.
Secondly how much sideways free play is there in the butterfly shaft on the carby. That's the one with the plate on top with a rod connecting it to the governor lever. If there is a fair amount of wiggle in it then that shaft is a scrapper and new ones are no longer available. It's easier to buy a replacement carby off eBay and replace the whole unit opposed to messing around with an old worn out unit that will leak air and give the engine a hunting effect while it's running.

Apart from that it's a full strip down for this particular machine as it's been sitting in a corrosive environment and just looking at the reel, rear roller and the engine tells me a fair amount of work will be required to bring this one back to it's former glory. That being said it's all just time and effort and you'll be surprised how well it will shine again.

Cheers,
BB.

Thanks BB, your enlightening opinion is very valued indeed.

Compression...yep...there is what feels like a fair bit...it blows my hard pressed thumb off the spark plug hole in no uncertain terms.

As for the carby...it just so happens I have just removed it and gave it a bit of a wash. The butterfly shaft you speak of is actually frozen and short of me using a pair of pliers or the like..'she ain't moving"

I have some pics of the carby for anyone to identify and if one the same isn't available or this one is unable to be re-kitted and overhauled...what is the best option ( and why )





of an eBay or Amazon one to replace it?

Can I assume that this is the original carby?...and if so...what was the correct part number so I can obtain a viable replacement?

Regards

Gazza

I think I may have answered at least one of my questions.

The flat 'tab' under the mixture and idle screws had some flakey paint on it...so I carefully removed the paint with a sharp pocket knife..and "Wallah!!!...the stamped number "302' appeared.

I used this number to cross reference on the following website and I came up with a Tecumseh Pt No of "631471"

http://www.tecumsehcarburetorguide.com/carburetor-identification/

Here's hoping I got it right

Regards

Gazza

Hi gazza,

Well I wouldn't worry too much about part numbers on that carby as you're not going to get a direct replacement number equivalent. You'll source one from eBay for around $30, but before you go down that road I would work on freeing up that butterfly and assessing the original because if that butterfly becomes fully serviceable then you'll be able to use that one.

Just keep soaking it with "Penetrene" etc. at both top and bottom friction areas, but do not force it via the flat plate on top as you'll bugger up the solid connectivity between the brass shaft and the plate with it becoming loose. Just be gentle with it.

If you have some carby cleaner in a spray can feel free to use that to.

Cheers,
BB.

Another thing that usually works well on gummed up carbies, is to soak it in acetone.
Needs to be in a closed container [glass or metal] so it doesn't evaporate too fast, though. And it will take all the paint off.

Hey BB, yup...you're dead right about not finding a similar carby...every part number under the sun and nothing even like it anywhere.
I'll take the Acetone path and really let it do it's stuff...I'll remove anything rubber or plastic before doing it though. It's a pity that "Carbusol" is now banned...I remember dunking an absolutely filthy Rochester 4 BBL in it many moons ago...dammm...I thought someone was playing a trick on me..it came out like brand spankers.

For authenticity I hope when I overhaul it will be fine.

As for cleaning out tiny passages and holes etc...I have managed to score a heap of tiny Dental files that are used to do root canals and things...very hand.

"Right said Fred"...here I go with another little missive...please do not adjust your screens or channels...normal transmission will return shortly.

I took Gadge's Acetone idea and the carby base minus the bowl now looks like brand new, the paint is sitting forlornly at the bottom of the large glass Pickle jar and the alloy carby body is fully nude and shining.

A small droplet of WD-40 on the butterfly shaft and with a slight grip via a pair of pointy nose pliers with which I gripped the shaft beneath the Governer Plate...it freed up and has nary a sign of any free play whatsoever. So..from this assessment it looks like I'll be able to rebuild this carby and keep the restoration authentic.

Question uno numero...how does one remove the brass Needle and Seat body?...it doesn't seem to have a flat tip scew driver slots in it which is pretty much the go for most carburator things these days.

Question Zwei... which kit do I procure via unknown means which will have the correct replacement parts I need? The Brass Float isn't damaged nor leaking that I can see and I will try to re-use it.

Are there any other tricks to removing any other internal parts that need to be replaced or cleaned as well.?

Cheers again

Gazza

Ok...next question for those in the know...where I have circled the head Bolt in the pic below, underneath I found a broken piece of what I'm thinking was 'spring' steel that was used as an engine stop device by shorting out the sparking plug. Since the plug cable is bereft of the usual rubber protective connecting cap...I figured that this maybe the reason why.

Any clues

Cheers

Gazza
(Have I bored you all to tears yet?)