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

ok so after getting my 45 on saturday and trying to use it today i have decided to do a restoration..

Today was a bit of a pain dealing with the kirby!!! first it wouldnt start so i cleaned the spark plug and away it went, I couldnt get the catcher to stay on then i couldnt get the motor to stop??? still dont know where the on off switch is!! then i went to start it again and i stuffed the pull start and cant get it to take the cable all the way back, i pulled it apart and its a mess!! and i have no idea where anything goes.

Even after the trouble with the Kirby i would still like to restor it but unsure what i need to comple an overhaul i would like to rebuild it from the ground up. if someone can point be in the direction for all the parts for the engine?

DJ, I suggest you start off by reading this thread:
https://www.outdoorking-forum.com.au/forum/u...s=Kirby-Lauson&Search=true#Post37736

Hi DJ1984, mate, hindsight is a wonderful thing.....but before you start pulling anything apart...especially if you have little or no experience...you need a plan of attack.

This includes taking pics before you attempt to disassemble, so you know how it goes back together.... and to post the pics here and ask questions; we can then help you....going at it willy-nilly will result in frustration for all and a non-running machine.
First you have to know what parts are required (if any) for the engine and then order them from the US.

I can help you with the resto of your chassis, grumpy will help you with the Kirby.
Please keep in mind that it is Xmas, and a few of our members will be away....

getting parts seems like its going to take a while so i might go down the road of replacing the motor for now and then restoring the kirby for a later date, the lawns are getting long and i dont think i can wait for parts so i might have to do this over the winter...

So what motor will bolt straight on the 70's 45

You need to measure the diameter of the crankshaft extension, where the clutch is attached to it. It will be either 3/4" or 5/8". If it is 5/8", either a Briggs and Stratton or a Honda of 3 to 4 hp will bolt straight on, subject to not getting one with a different shaft length from the original. If it is 3/4", you would need to buy a replacement clutch-half of the 5/8" size for around $85. Other than that point, the replacement is a simple bolt-on fit.

Whether you choose a Briggs or Honda is a question of what you want to pay, and what access you have to good second-hand engines in your area. At one extreme, an old 1970s or 80s Briggs Model 80202 should cost very little, and was the engine that replaced the Kirby-Lauson as original equipment on that mower during the 1970s. At the opposite extreme, a new Honda GX120 is the nicest engine, but rather expensive. There are many intermediate solutions between these extremes.

ok so i have removed the engine but cant seem to get the clutch off the engine?? i have taken two pins out that are holding the clutch on but its not budging? and advice on how to get it off?

Please post some pictures of this DJ. The engine side of the clutch is normally held to the engine's crankshaft extension (or PTO) by either a captive cotter pin or a couple of grub-screws. I don't know what these two pins are.

i just screwd the pins in by about a thread just to show you were they were, there doesnt seem to be any grub screws under them but there is a keyway under one of the bolts..

just a question, is this forum supported by taptalk? would make it easy to get photos from my phone to this forum?

After a closer inspection I'm pretty sure it's held in by a key, and looks little bent

Those are technicaly grub screws, though they do not appear to be the normal type for that job. One of the screws should be directly above the key, so it is pressing the key down, which I think is what you said.

If you back out both grubscrews, the clutch should only be held on the crankshaft by friction. Once you unbolt the engine from the mower deck, fairly gentle use of a lever between the crankcase cover and clutch boss should push the two apart.

Seems to be stuck solid, I have tried everything, I have bring it to work with me tonight to see if the engineers can get it off for me...

They are the correct grub screws supplied with the engine side clutch half.

Separating the clutch halves might be a good idea (inspect the internals at the same time) and some Penetrene down the keyway....if there is surface rust on the engine shaft, it may prove troublesome to get off.

this thing is not coming off!! i have even gave it a bit of a beating to get it off but it seems like its welded on!! i pulled the clutch apart and its stuffed!! i might have to but that end of the housing...

If you separate the two halves of the clutch, can't you pull the engine-side half off the crankshaft extension with a gear puller? Be sure and soak the shaft and keyway area with Penetrene first.

Hey DJ1984
If you plan on keeping the mower for a while, and don't have a complete allegiance to restore to exact original specs, you can buy a number of new engines for a relatively cheap price.

I bought a brand new briggs for under $300, and many have purchased the very reliable Honda for a tad more.

In respect to the rest of e mower, many threads on here on what people have done. You can go quite extravagant (funky new front rollers avail etc) or can do on a budget if that's your choice.

I did mine with lots of help by seeing what others had done, or simply ask for help.

ok so i went to use a gear puller and got the other side of the clutch off but couldn't get it off all the way instead i made a nice thread inside the clutch and its now stuffed!! the keyway is ground off so it looks like ill need a new one, the shaft on the kirby was 5/8 so can someone point me to what i need and where to get it?

i also might aswell get some new bolts for the engine housing and clutch, might aswell replace the spring too. i lost one of the engine bolts...

there was also a half moon bit of steel i think it was aluminum, i think it come from the other side of the clutch but it fell out and im not sure where it come from? i lost that aswell not sure if i need it or what it was..

DJ, I don't want to intrude into what went wrong, but it would be useful for you to think it through. At present it sounds as if you cut an internal thread in the engine-side clutch half by using a gear puller with a thread on the screw that was larger than 5/8" diameter. That would be a remarkably large gear puller - the biggest one I have only has a 5/8" thread. While I would not put it into a 5/8" bore, the marks it would make would be superficial unless the puller were off-center. It would be helpful if you posted pictures of the damaged clutch-half, partly to help other people in the future, and partly because we can then discuss whether it is really damaged so much that it has to be thrown away. Anyway, all of that is your business, but it would be a pity if you became disenchanted with gear pullers instead of working out what went wrong.

You seem to have said that you cut the other side of the clutch off rather than removing the three screws that hold the two halves of the clutch together. Again, I don't see why you would do that since it would be likely to damage at least one of the clutch halves.

I do not understand your description of the damage to the straight key from the crankshaft extension - a picture would be helpful. The "half-moon" you mentioned sounds like the Woodruff key that drives the clutch shaft, Item 111 in the illustrated parts list:


That item is Part Number 3802267. Please confirm that is the piece you were talking about.

Deejay can help you sort out what to do next, I am just asking for clarifications so that people who read this thread can follow what is happening and why it happened.

ok so ill let you know what happend in detail... i bought a new puller and it seemd to fit was not tight or anything and i proceded to use it, the tip of the puller is smaller than the 5/8 but the rest of the shaft must be bigger, i started getting the clutch half to come off when i found some resistance i just thought it was getting to a tough spot on the motor shaft so i started to use force, i got a few turns in and seen the clutch half wasnt comming off and i had screwed the puller into the housing of the clutch half.

I havent cut anything i have done everything the same way as deejays youtube video apart from the drama of getting the pully off.

My wife is starting to give me greif because i swapped my perfectly good and new masport mower for "this peice of junk" but im still keen to get it going and in winter when the lawn slows down ill be fully restoring it minus the new motor once i get the motor in of course.

Hi DJ, mate for us to help you, we need pics of:
(a) the puller you bought.
(b)the inner clutch half where it is damaged
(c) one of the Briggs engine shaft with its keyway exposed.
Please post these asap, and we will advise you further.