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Collection, Preservation and Display of Old Lawn Mowers

Qualcast 43SL - My first cylinder

Hello, looking for some resource help please..

OK, hardly exotic, but my first cylinder mower...I have purchased a Qualcast 35s from the ubiquitous auction site and collect it on Monday.

Operating condition is unknown, but even if it is working straight off I want to give it a good service and get it running nice before spring.

Questions I have and grateful for any feedback on..


Can I download manuals from here? If not do you know of a resource please?

I’ve seen ads for these Multisharp cylinder sharpening jobbies, are they worth getting or is there a better way?

Are there any know issues or idiosyncrasies with this model?


Many thanks in advance



wristpin Fri, 03/11/2017

Welcome to OLC. Your Qualcast will be a good starter project, with  plenty of information and a good supply of parts.

When you get the machine home , take a few images and post them on this forum and then we should be able to supply the appropriate information.

Not a fan of those diy sharpening kits but let’s see the condition of the cylinder and bottom blade.

Chris G Sat, 04/11/2017

Hello, many thanks.

I will get some photos up on Monday, fingers crossed it does not have anything seriously wrong with it.

It looked ok from the image but sold as condition not known, barn find....

Chris G Mon, 06/11/2017

Hello all,

Went to pick up the mower tonight and got a bit more Punch than I expected. The sellers boss had taken over a contract and selling a load of machinery that came part of the insource to his outsource deal, basically scrap as far as they are concerned...

So it's a 43s. So far all I have done is got it home into the shed, the starter cord operates free enough, the fuel tank is a bit rusty at the bottom and holding nothing more than what seems condensation, the operating cables pull and retract ok but look a bit worse for wear, the rear roller hardly moves! I am guessing it should even when not running? The control handles are clearly not straight but that might be just tightening up of the bolts.

Hope the pictures work, where do you think my priorities should be as a proper inspection?

Many thanks


wristpin Mon, 06/11/2017

Seen a lot worse, quite clean and tidy. First check, how much oil in the crankcase - hopefully, plenty.

As far as it’s reluctance to move goes, have a look inside the cover on the side of the right hand chassis member. If the belt can’t slide on the pulleys when disengaged it will act like a brake on the roller drive.

Chris G Tue, 07/11/2017

That is very helpful! thank you very much - downloaded and printed.

The oil is at the filler hole lip per the book, so could bode well for the motor. I will change it though. The air filter looks like its never been cleaned and the spark plug was super sooty so I'm guessing its been running a bit rich or the air filter being so clogged may not have helped..Plug gap is no where near what the book says it should be either

Took a look at the belt as you advised and it had come off the centre roller, see pic. I have put it back on, but is that centre roller supposed to rotate? as currently it is siezed - or does the belt just slide over the top of it?


wristpin Tue, 07/11/2017

That roller should rotate.

Running with a blocked air filter is the equivalent of running on choke. There were some changes to the recommended plug gap - I'll dig out the bulletin .

Chris G Tue, 07/11/2017

Thanks a lot Wrist Pin. The gap was at about 0.5mm and the book says 1mm so have adjusted it to 1mm for now.

That centre roller is not exploded in the book, but have taken the circlip off and squirted some penetrating oil in and it ain't budgin :-) I may leave it overnight and have another go in the morning. But I think I am going to have to remove the whole centre roller bracket affair as the bracket is a bit weedy and I don't want to force it too hard as it might distort the bracket.

It looks like the centre pin on that roller has a bush over it then the outer wheel?, it appears that all 3 are fused together and I can't really get anything behind to squeeze it off. So may need to dismantle that, get it in a vice and tap off from behind. Hoping this is the main reason it was going for a song..

Still not started it yet - its so exciting (sad I know)

hillsider Tue, 07/11/2017

The roller has a sintered bronze bush pressed firmly into it and should be free to turn on the steel spindle.

It is possible that your soaking will free it by softening the dried grease that is probably holding it fast, but if not then yes do remove the complete arm to apply extra force without bending the support bracket. 

When you refit the roller arm and adjust the cable don't fall into the trap of over tensioning the cable as that will also cause the roller to drag. The adjuster only needs to be set so that the drive takes up as the clutch lever is almost touching the handlebars when pulled in.

wristpin Tue, 07/11/2017

Rather than try to lever the jockey pulley off its spindle try gripping it around the rim with vice grips or stillsons (with suitable protection) and rotating it a degree or two at a time back and forth . If it starts to move apply penetrating oil and gradually increase the rotation. Hopefully it will free off . If that fails, remove it with the arm and support the pulley on the jaws of the vice with the arm free to move between the jaws and then try tapping the spindle out with a hammer and drift. 

This may be of interest…

Chris G Wed, 08/11/2017

Wrist Pin, Hillsider, thanks again for the guidance, after 24 hours of regular squirting and trying to rotate gently with some stilsons it still would not budge, even bracing the bracket and applying more force would not move the roller so I had to take it off.  The centre pin had raised corrosion which was stuck fast to the bush, once in the vice it was tapped off in seconds, polished it up and greased and is now moving fine so will reassemble tonight I hope. I take the point on not tightening the tension on the cable, thanks for that, the cable does not look in good shape and was already backed out a fair way, the throttle cable is also in pretty poor shape so will likely replace both once I get it started.Getting the rust out of the tank and sealing it is my next job before I try to start it.

Wrist Pin,  that technical bulletin is very useful also thanks for that, on the plug gap for the A114 engine it states 1.0mm pre 89 and 0.6 post 89. Would I be safe in assuming it’s a post 89 and a 0.6 gap?


Chris G Wed, 08/11/2017

Sorry for the serial posting...

I have got the clutch roller mech all back in and its now moving fine and the belt is staying in place, I have adjusted the cable but hve had to adjust it all the way back in from where it was set to get it to engage the roller later on the pull of the lever, it was backed almost all the way out initially, guess that may have been trying to fix the pulley issue..It engages the roller about half way pulled up on the level now but its not started under load so will see once I start it.

I have been inspecting as I go around and found the left side chain case guard has had a serous biff. 

I'm assuming the 2nd lower hole should not be there and has just been ground out by the sprocket retaining nut? also on the the proper case retaining bolt there is a nut on the inside, will have to look at the diagrams but guess this was just added to try and nip the 2 nuts up?

Pretty sure I can fix all this by cold forming (bashing) the panel back into good shape, but the threads on the end of the sprocket shaft do not look great if I have to get that off.

I think this machine has had very unsympathetic use..

wristpin Thu, 09/11/2017

All about par for the course on a well used / abused machine.!  The chain case should be retained by a slot head screw going into a threaded boss cast into the LH chassis side plate. You have the standard repair for one that's suffered a bash too far breaking the boss out and leaving a jagged hole. An after market supplier used to produce a a repair kit for that but studding and penny washers do the trick!

Another common issue - out of shot in your images  - is the top sprocket coming loose and fretting on the clutch shaft  flats and eventually wearing the shaft oval.

Chris G Fri, 10/11/2017

Thanks for that., Done a bit more of a robust job on that stud and shaping the panel on.

Will check the upper sprocket also, chain guide needs adjusting anyway – way too much play according to book.

Will adjust plug back to 0.6mm.

Fuel tank is done.


Plan is to fire up this weekend!


Have noticed a crack in the filler cap, I see it has a vent anyway – is this crack a “feature” people live with?

Also noticed what looks like  .22 calibre “pot shot” in the starter cover so that’s coming off tomorrow night…





wristpin Fri, 10/11/2017

Chain . Take account that adjusting  the cylinder to the bottom blades tightens the chain. Over tightening the chain will wear the cylinder Bearings and the spherical bush that the clutch shaft runs in.

Fuel cap. Fill the crack with Araldite or similar but leave a breather hole.

Starter cover. Just damage to the decal where it covers an indentation or screw in the starter cover.


Chris G Fri, 10/11/2017

Wrist Pin, just read the chain tips, hmmm will slaken it off a bit now., you are correct on the starter - no issues there.

Today - One step froward 2 steps back :-(

Refiited the fuel tank, filled with fuel. The tapp on/off seems to do what it likes.... but the major problem was that fuel just poured out of the carb, so much it was hard to tell from looked like it was coming out of the bottom bowl retaining nut but also came up and through the air filter! The throttle was on stop..

Help! - any ideas

hortimech Fri, 10/11/2017

Fuel coming out of the retaining nut, missing or damaged fibre washer.

Fuel coming out of the air filter, this sounds like either a stuck float or grit in the fuel needle. It sounds like you need to remove, strip and clean the carb.

Chris G Fri, 10/11/2017

I really don't have much experience with carbs (other than bad) and I am stuck already..Float bowl was full of rusted sludge and some corrosion to the inside of the bowl itself, dealing with that now.

I have an air line and need to get some carb cleaner spray tomorrow.

Don't want to force anything.. Is the float retaining pin supposed to slide off? I have dremeled off the corrosion at the ends of the pin but its not moving in either direction, does it unclip another way? 

Many thanks


wristpin Sat, 11/11/2017

Obviously been standing with water in the system - check the inside of the fuel tank.

That pin should slide out. You could try a kettle of boiling water over the pin and mounting lugs or an over night soak in penetrating fluid such as Plus Gas or diesel . If you can grip one end of the pin , try rotating it . Resist the temptation to apply too much linear force before using penetrating fluid as its not unknown for one of he mounting lugs to part company. A cheap automatic centre punch with the pointed end ground flat makes a mini impact tool but support the opposite lug with a small socket or bit of tube against something solid while using it.

With the pin out, your troubles may not be over. I believe that your machine will have a Dellorto carburettor and almost certainly the main jet / emulsion tube, that is screwed inside the centre stack, will resist removal. (item 1 on page 15 of the scanned manual that I posted earlier. That jet has a tempting screwdriver slot which requires a special or modified screwdriver to remove it without damaging either itself or the internal thread in the soft alloy stack. The screwdriver needs to be a good square fit in the jet's slot - not tapered ; and parallel so that it doesn't ream out the internal threads of the stack. With the plastic float out of the way you can apply gentle heat to the out side of the stack or boil the whole carb up in a pan on the stove. I cant over emphasise the need to tackle the jet removal in a planned and controlled manner - chew up the slot at your peril!


Chris G Sat, 11/11/2017

Really appreciate all the help on this, not sure where I would be without it so far.

The tank did have some water in it, I did clean flush and dry it before the attempt but have not sealed it yet as I wanted to see if the motor would start.It has some rust at the bottom and I don't think the tap is working properly but can revisit that and possibly use a dummy tank for trial purpose.

The carb is a Dellorto FCH20.13A - the downloads have been very useful.

I'm going to follow carefully the steps to remove as advised.

Fingers crossed, I maybe some time...

Chris G Sun, 12/11/2017

Softjaws in the vice, carefully dremelled as much rust off the float pin as possible in situ and syringed diesel over it for many hours, then long nose pliers gently rotating – more diesel – more hours – more rotating, eventually started to move gently laterally and it was soon on the march and out. See what you mean about the risk of snapping off the pin retaining mounts, there is hardly any meat there! Wet and dry paper on the pin until completely smooth.

I was really lucky with the main jet, again many hours of syringing diesel and wafting hot air gun, found a driver bit from a morgan carb tune kit that fitted well , square and no interference with the stack threads, it came out without issue. Should have taken a before pic, every hole was blocked.

Put everything other than the gaskets into ultrasonic cleaner with high IPA hot solution and even though I had cleaned the exterior the water was filthy in no time, did this about 4 times until water was clear, then airline thoroughly. It now looks super clean inside and out – fingers crossed.

Concerns I still have J haha – will the bowl push button still seal after removing all that corrosion, will the float pin corrode and bind again, and I have reused all the gaskets…

The fuel tank “tap” is now working and holding properly when off. Although the fuel is running clear after a good clean out there is still rust in the tank, especially in the bottom seams. I was going to seal it with POR15 but is the tap removable? more importantly would it go back on fuel tight?






wristpin Sun, 12/11/2017

All good but despite the ultra sonic clean there is one possible stumbling block. If you look at the Venturi where the throttle valve shuts you will see three minute holes . These are the slow running and progression jets and are fed via a small chamber covered by a Welch plug in the side of the carb body. The problem there is that although the U/S action can loosen any crud that may be in there , it may be trapped ready to block those orifices again. If that happens the only course of action is to hook the plug out. Replacement plugs are available but it may involve raiding a rebuild kit or an after- market box of assorted plugs. However, if you remove the plug by drilling a small hole and wiggling it out with a  scriber , you can replace it with a smear of sealer and fill the hole with Araldite or similar epoxy.

The plastic tap does unscrew. It has very fine threads and requires care to refit without cross threading.     I’ve never bothered with tank sealant but if you do , choose a brand that is guaranteed ethanol resistant as there are stories of the cured sealant going crispy and collapsing internally . I clean steel tanks by electrolysis but if there is only a bit of rust in the bottom seam you could pour in sone rust converter such as  Kurust  and leaving it for an hour or two . When you have it all up and running using an ethanol resistant fuel stabiliser will keep things running smoothly.



Chris G Mon, 13/11/2017

Right, thanks I will look at the Venturi when I get back at the weekend.

Good shout on the electrolysis rather than seal for this issue on such a small tank, I will do that rather than remove the tap.

Still hoping to fire up at the weekend, we shall see...

Chris G Thu, 16/11/2017

It lives :-)

Once warmed up off choke it's actually idling pretty well and the motor feels strong and nice with the revs up and the clutch engaging cylinder drive. I couldn't run it around too far in my little garage, but confident now I have a going concern so changed the oil while it was warm.

Few little things to sort and tweak like the chain drive again, the throttle stop doesn't, but the annoying issue of the fuel tap leaking badly has returned.

The cap vent seems to be venting ok, the tap itself is not leaking from the body where it connects to the tank. What seems to be happening is that its leaking from around the top of the on/off plunger regardless if its on or off, not a small weep either...No idea what the inner construction of this plunger tap is, but it seems to get more positive (firmer to pull and push) the longer it has fuel in it, so I am wondering if its a dry rubber seal which is expanding and making better contact seal the longer its immersed in fuel..? Will test a bit more and see if it stops leaking, if not it will have to come off and get stripped which I was hoping to avoid.

If I have to take the tap off I am tempted to blat the inside of the tank with phosphoric acid solution and then seal with POR - I've done loads of motorcycle fuel tanks like this with great success, basically replacing all the POR prep chemicals with the active ingredient chemicals that can be bought bulk and cheap!

If the tap stays I will run the electrolysis process, got some copper plate or is basic steel better? got some washing soda somewhere as well I think...


Chris G Fri, 17/11/2017

Big thanks to Wristpin, Hillsider, Hortimech and this site.


Mechanically and fueling wise (famous last words..) this seems finished and running well. Lick of paint to head and exhaust (Calfire satin stove spray paint 650c ) and that’s it cosmetically, there is too much good original paint on this to paint anymore. I’ve got the fuel tank cowl looking pretty good, but its such a useless carbuncle I doubt I will refit it. The grass box is great too, no doubt rarely used by the gardening contractor..


Last piece of advice I would hope for is a steer on cylinder recon, sharpening, painting.

After reading some posts on here, I have shelved fixing a sharpener thing and put my angle grinder back on the shelf J

I live near Milton Keynes, can anyone recommend a good service? I could take the whole mower or remove the cylinder and post.


Thanks a lot



wristpin Fri, 17/11/2017

There’s at least one postal sharpening service offered on eBay and another OLC member had recently reported  favourably. 

wristpin Sat, 18/11/2017

The cap vent seems to be venting ok, the tap itself is not leaking from the body where it connects to the tank. What seems to be happening is that its leaking from around the top of the on/off plunger regardless if its on or off, not a small weep either...No idea what the inner construction of this plunger tap is, but it seems to get more positive (firmer to pull and push) the longer it has fuel in it, so I am wondering if its a dry rubber seal which is expanding and making better contact seal the longer its immersed in fuel..? Will test a bit more and see if it stops leaking, if not it will have to come off and get stripped which I was hoping to avoid.

I thought that someone else would comment on that but as they haven’t, here goes.

The old brass taps are repairable, either with a new plunger/ cork assembly or a new cork from eBay to renovate your plunger.

The OEM  plastic taps are throwaway items. The originals had a red grip to the plunger and a 3/16 “ pipe spigot the later ones with increased fuel flow had a yellow grip and a 1/4” spigot.  In addition there are various pattern ones from after-market suppliers. 

It’s quite likely that whatever the sealing medium is in the plastic taps will swell in use but they are cheap to replace.

Chris G Sat, 18/11/2017

Indeed, the cause and effect of drying out the tank twice proved that the tap would leak for a fair while once refilled.

I've got the yellow grip 1/4 plunger type which is not leaking at all since its had fuel in for a few days. But I don't like the risk or action of the plunger so have ordered a rotary lever type and like the idea it has a mesh filter - as long as it does not reduce fuel flow or get blocked up! 

wristpin Sat, 18/11/2017

Your yellow grip would have originally had a mesh filter so I doubt whether your new tap will cause any starvation issues - unless you’ve chipped the motor!

Chris G Sun, 19/11/2017

Now that would be a thing :-) throw in some fuel injection...

There was no brass mesh filter on mine, not surprising there was 3-4mm of rust sludge in the float bowl!

wristpin Sun, 19/11/2017

I recently read in the trade press that Stihl are in the final development stage of a chain saw with no carburettor but with electronically controlled fuel injection so the idea is not too far fetched.

Chris G Sun, 19/11/2017

Packaging that must be a real challenge. For sure its not going to draw a lot of current but will need a fuel pump of some sort I would have thought, the electronic management would likely fit into a match box these days, but how would that all get powered from the start?

If it would need a battery, why would they not go down the route of the cutting edge battery development thats going on and power the whole thing via that. Too much stop start I guess, but does seem an exercise in what can be done versus whats practical in that application - like a simple tank, carb, plug and pull cord :-) 

Chris G Mon, 20/11/2017

Hello, I am just starting to take the cylinder cutter out and following the exploded parts diagram.

Probably a daft but fundamental question.. do one of the side plates need to come off to get the cylinder spindle clear or is there a nifty way to do this?

I have only taken the outer clutch side components off so far.


Thank you.

hillsider Mon, 20/11/2017

You did well finding that info, it looks as if the subject was covered fairly comprehensively back then. So it only needs me to say take your time and keep bolts and nuts safe in a container. It might be helpful if you take pictures as you dismantle to help when it comes to the time for putting the mower back together again particularly if the machine is in bits for a week or two.


Chris G Tue, 21/11/2017

I am putting the parts I'm taking off the cylinder spindle in order on a rod separated by cable ties, left, right, inner etc - good shout on taking pics, my ability to loose things is only surpassed by my lack of memory.

Having taken the bottom blade off and looking closely at the cylinder, I am sorely tempted to clean it all up in my little sandblaster, very lightly follow the flat contour of the blades with a power file, dress the bottom flats of the blades with emery and then paint cleaning off the blade edges. Is this foolhardy ?


hortimech Tue, 21/11/2017

And then again, you probably wont be ;-)

Also, when you do decide it will have to be ground, whoever does the grinding will hate you because the cylinder blades will be all shapes.


Chris G Wed, 22/11/2017

OK I get the message :-), one reason I was going to give the sharpening a go, is that I saw a post on here where someone had got it done and it looked a poor angle finish. Also other than my own effort I have put little money in it so far, but this might be a false economy. Have seen an add for a service near Yarmouth which I will contact.


Chris G Wed, 22/11/2017

Thanks Wristpin, I have followed that diagram diligently.

The cylinder put up a real fight, so much so I thought I had omitted removing something, took my time tapping gently to move the R/H cover, it was seized on the bearings..

hortimech Wed, 22/11/2017

I would have stripped it down a little differently, removed the engine and delivery plate (concave, grass deflector), I would also have removed the other frame side.

You have stripped it down though and that is the main thing, all you have to do now is, remember how to put it back together again ;-)

Chris G Fri, 24/11/2017

Now I have stripped down this far, I see what you mean, its not much of a job to go that route.

Deflector is badly rusted at rear and quite bent so will sort that, mine seems to have been painted hammerite silver, have a pot of that so its getting the same.

Cylinder and bottom blade off to the man in Hemsby tomorrow - still think I should have done it my self :-)

Spindle ends were bit of a mess and a bit pitted, so polished them up - I am aware I need help lol

Chris G Thu, 30/11/2017

Picked up cylinder and bottom blade from Steve today, I'm no expert for sure, but looks an excellent job, nice angle and super sharp, bottom blade too, Nice thick paint,

£23 all in !!! I was mad to even contemplate it at that price.

Steve's in Hemsby Norfolk, but he does do postal,

Might have been posted before but link to his ebay listing below - much easier & cheaper to email him direct for a price.

Will look to fit tonight.…


hillsider Thu, 30/11/2017

Looks a nice job but I do hope that you have not gripped the cutting blades in that vice or you could have fun trying to set the cut?

Chris G Thu, 30/11/2017

Haha :-) nooo just resting on some rubber softjaws.

I've ordered some Qualcast green paint for the bottom blade and panels (given the cylinder, deflector, engine and carb now showing everything else up..)

So idea was to fit the cylinder, which I have almost done, and then fit the bottom blade after.

I can see that the bottom blade retaining top nut is not retained! so when trying to install the bottom blade the bolt will likely dislodge the nut - great !

Should I drop the bolt from the top first and do the nut up from below (reverse of what the diagram says for corrosion reasons I think...)

Should I wait and repaint the blade then fit first then cylinder (unlikely - too impatient)

Trialed a magnetic bendy stick thing where I could possibly feed the nut while doing up the bottom bolt..why didn't they design a captive nut!

Any tricks I've missed?



wristpin Thu, 30/11/2017

Never had an issue with those nuts. Just put them in place and offer up the bolts while turning them so that they pick up the thread in the nut. If that doesn’t work for you, either “ secure “ the nuts with heavy grease or wrap a bit of masking tape round them to jam them into place.