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Atco mower with JAP side valve engine info needed

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Hi,

I have just acquired an Atco lawn mower that is powered by a J.A.P. engine.  The engine has a serial number which dates it to 1936 but so far I have not been able to locate any information on either the mower or the engine, both of which will be needed for the restoration. The cylinder cutter is 20" width and was probably a bowling green mower or  for golf course use.  The Standard model has some similarities, but the side frames are plate steel and not castings.

Any help here or a pdf of engine or mower operating manual or parts list would be very welcome.

Mike.

 

Forums

wristpin Tue, 03/11/2015

Welcome to the forum. A couple of images may make it easier for  us to positively identify the machine.

sparkymike Wed, 04/11/2015

What are the two vertical square headed screws for . (See arrows on photo) Grass deflector plate ? If so, I will need one, or a drawing.

Mike.

wristpin Wed, 04/11/2015

Those screws adjust the "nip" between the rotating blades and the fixed bottom blade, probably by rotating the whole sole plate (bottom blade carrier) around two pivot bolts lower down. In some applications two screws will work against springs and in others there will be two screws each side  - with a "horn" on the sole plate clamped between them so that you back off one and tighten the opposing one to move the horn in either direction. They are clearer in that ebay image that you posted.

sir_chook Wed, 04/11/2015

Hi Mike,

That would be a 20" Atco De Luxe. They are a nice old mower made between about 1935 and the beginning of the war. I have a 2 stroke version and it is a real beast of a mower. Engine would be a 350cc J.A.P side valve.

Cheers,

Sir Chook

sparkymike Wed, 04/11/2015

Now had a chance to take a closer look at the bottom blade adjusters. The front and back screw brings the bottom blade closer or further from the cylinder. The top screw is not for adjusting purposes, but I suspect it is for a grass deflector or some other accessory.

Mike. (See photo)

wristpin Wed, 04/11/2015

That's it, and Atco still used a version of that system right up to the last 20, 24 and 30 inch heavy duty machines that they made . 

sparkymike Wed, 04/11/2015

To date, the engine would not start and the three essentials, ie. compression / spark and fuel were all missing when I first got the machine.

The fuel side is now sorted and I had to make a new copper fuel pipe from tank to carb as the original one had a section missing for some weird reason. Next problem was a blocked jet on the Amal carb. I found plenty of info on these on the net. This model is a pre-monobloc type and was common on many motor cycles of the same era.

Compression mainly turned out to be a stuck open exhaust valve. Cylinder head comes off in five minutes or less which is handy.

While the engine top is open I decided to check the valve seats and now have them refaced and have as yet, to grind them in.

The oil pump is similar to the Pilgrim pump that was often found on the JAP engines. I believe it could be a Best. I need to do more Googling to check. I do not know if this engine is a total loss system, or if there is a sump. There is a cover on the fan side of the engine near the base with four c/snk. screws, but none of these will budge yet so I expect a little help with the gas torch will be needed.

There is a short stub pipe (copper) on the rear of the engine just above the crankshaft level. Anyone know if this is a breather or perhaps an overflow for excess oiling ?

Mike.

wristpin Wed, 04/11/2015

Sounds like you're making progress. Don't think that it will be a total loss system - ie the "used oil" goes out with the exhaust as on a Field Marshall tractor giving rise to the medical condition known as Marshall Measles!  Could be a dry sump system where the oil is supplied from, and scavenged back to,a separate oil tank but I cant see one in your images so perhaps it just has a conventional sump. Does that " breather" pipe have any sort of one way valve in it?

I'm sure that a JAP owner will enlighten us.

sparkymike Thu, 05/11/2015

The" breather" pipe is just a straight bit of copper pipe but there could well be a valve in the engine. I have to contact a motorcycle mate who may well be able to give me more information.

This machine is no lightweight, we had to lift it off the pickup with my engine crane. !!

It has steel front rollers and they seem fine in the bores except the outer ends which I  will need bushing, unless there is a reason for them to be slack. It could be that they just pick up more grit on the ends so get more wear.

Mike.

wristpin Thu, 05/11/2015

Old mowers tend to be heavy but have their uses !  I've just given my Dad's 1930s Dennis an outing to roll the "lawn"  which suffered a bit when I had a gang of tree men in removing some overgrown leylandi.

The outer rollers always seem to wear more both on the internal and external diameters, whether they are steel, wood or , on more modern machines, plastic.  When servicing machines with multiple equal sized roller sections we always used to juggle them around to even out the wear. Outer wooden rollers often wear to a distinct taper.

 

sparkymike Thu, 05/11/2015

Re. steel rollers

Are they solid steel or are they bushed ?    There is quite a bit of side play ie. around 10 mm.

Is this normal or caused by wear on the roller faces?

Thanks for advice so far, it all helps.

Mike.

wristpin Thu, 05/11/2015

I've no specific knowledge of Atcos of that age but would guess that the rollers are not " solid" but are steel drums , possibly with bushes pressed into the end caps with a washer between each section; or, top hat bushes with their " brims" taking the end thrust between the sections. 

A bit of longitudinal movement of the roller sections along their shaft may not look pretty but won't really affect the machine's  operation but excessive radial wear between the rollers and their shaft may make it difficult to obtain a level finish - always assuming that the lawn is good enough for it to show up !

sparkymike Fri, 06/11/2015

While de-rusting parts of the handles, I noticed that where the clutch lever locks, there was script on the tube that could just be made out to read "clutch"

There are two other words either side of clutch, but can not decipher these as they are nearly worn away. I have a friend who does sign writing if I can find out what the words are.  (In and Out maybe ??)

Mike.

 

sparkymike Sat, 07/11/2015

I refaced the valves and ground them in but the engine still will not start, so I gave it a compression test and only get around 60psi.

There is not enough suction to pull the fuel in.

I would have thought that around 100 would be minimum figure, so I have to remove the cylinder and check if the rings have stuck up, which is most likely, due to the time it has been in an unused state.  I have at last found some handy info on the engine, via a site that dealt in Howard rotovators . This is about the JAP mk. 3 which although later than mine, has many similarities.

Mike.

 

wristpin Sat, 07/11/2015

Squirt a bit of engine oil through the plug hole and see if it raises the compression. If it does you are probably right about stuck or worn rings or even bore wear. If it doesn't your newly fettled valves are not sealing.

sparkymike Sat, 07/11/2015

Hi Wristpin,

I am convinced it is bad or stuck rings, so it should be easy job to remove the barrel to check. Mind you, I can hear a pressure build up in the valve spring chest , when the piston goes down, so maybe rings are ok !!  Last time this machine as run must be 20 or 30 odd years or more, so worth a look see.

Mike

arnk Mon, 09/11/2015

Mike

Please can you post a picture of the kick start mechanism for me - I am assuming it has one, but I can't see it clearly.

I have a 1930s heavyweight, also a 2 stroke like Sir Chook, so not as heavy as yours.  My kick start mechanism is faulty, but it may not be original, hence the photo request.

Have you tried a different spark plug?  Mine had a Lodge that would spark outside the engine, but not under compression.  When I tested with an old NGK it worked.

No words on my Atco next to the clutch lever as far as I can tell.

Al

 

 

sparkymike Mon, 09/11/2015

Hi Al, I will take a photo of the kick start mechanism tomorrow if all goes to plan. (does it ever !!!)

I now have the barrel off and piston and rings all look in top condition and quite clean. This was not the easy job that it first looked to be, There is an oil feed pipe union that blocks off any access to one of the four nuts that hold the cylinder in place. Someone in the past had roughly nibbled a small semi circular notch out of the bottom cylinder fin, but not quite deep enough to remove aforesaid union nut, so I ground out the circle carefully with a burr in a battery drill which solved the problem. Once the barrel was off, I made a much neater job with a larger burr.

Looking at the timing gears, they were not lining up with the timing marks, but around two teeth off ,so this could have a bearing on the start problem. Mind you, timing marks can not be relied on and also one of the gears could have been replaced. We shall see....  I have taken a photo of the timing chest that I will post ,as it may well help other owners with the same or similar engine.

Mike.

wristpin Tue, 10/11/2015

Not usually the marks that are the problem but the person who fitted the gears!  Does your Howard info  have anything useful on valve timing etc. If " finger blight" is suspected it's always useful ?

sparkymike Tue, 10/11/2015

I have yet to master the script/photo settings so any help here would be handy.

Al, I have two more photos if you need from different angles.

Mike.

sparkymike Tue, 10/11/2015

Hi Wrist pin. Photo of timing marks. These could hardly be seen, a small arrow on the cam gear and a dot on the crank gear. The photo is larger than life and picks them out easily. The insides of the engine was quite black but gradually improving.!!

sparkymike Tue, 10/11/2015

Hi Al, another photo of the kick start. Interesting point is the Villiers Midget script on the gear lock ring ?

sparkymike Sat, 14/11/2015

I am progressing with the mower, but have come to a halt with the cone clutch. This looks to be identical to the clutch as used on the earlier Standard model. The clutch operates fine, but I would like to clean all the individual parts and remove grit/dirt from the bearings.

If needed, can the clutch linings be obtained ?l

What is the sequence of removal for clutch/countershaft and chain sprockets ?

One other point, can bottom bades be obtained for these machines and if so, where ?

Mike.

wristpin Sat, 14/11/2015

Last question first last question first!  You may find that the blades from later Atcos right through to the last machines made under their own name, will fit. Certainly when I restored an HY I took one straight off the shelf of our current stock. Failing that, Garffitts will either have one or will make one for you.

Clutch linings. Unless someone else on the forum can point you straight to a specific supplier I suggest that you trawl the vintage motor bike and car scene. Obviously, today, any replacement will be asbestos free but the original possibly will not be so when dismantling damp everything down and spare the air line! 

I can't offer any advice re the dismantling sequence but don't recollect encountering any issues with the few standards that I've worked on.

 

sparkymike Sat, 14/11/2015

Thanks Wrist pin. That is reassuring re. new bottom blades, as the original bottom blade does look a bit suspect, but I need to remove it first for a closer look see.

I now have the JAP engine crankcase open and glad to say that there is no drama and all looks to be remarkably good which is a nice change after the V twin that I am also rebuilding, that had been "got at" by many previous owners !!

Mike.

sparkymike Sun, 15/11/2015

A question re. the J.A.P engine.  How do you remove the timing gear from the crankshaft spindle ?  There are no key slots visible, so thought I would ask before doing any damage with a puller. On the flywheel side crank case that I have removed yesterday,the oil hole to the main roller bearing was blocked with crud, so I would like to check the timing side, before I assemble the engine in case the same fault is present on that side as well. As I see it, the inner flywheels and crankshaft are not removable until the timing pinion is off the shaft.

Failing crankshaft/flywheels removal, I could just flush out the remaining crankcase side in de-greaser fluid .

For the record, I counted 17 roller bearings on the drive side. With all 17 in place, there is a gap, but not wide enough to take a further roller.

For future reference, would it be a good idea for me to post some more photos of the engine internals ?

Mike.

 

wristpin Thu, 19/11/2015

I would be satisfied with thoroughly flushing out the oil ways. Disturbing the gear or the crankshaft balance weights may cause more problems than it solves!

As a general principle a roller race is not "packed solid" and yours sound about right - unless anyone with specific JAP knowledge knows otherwise.

sparkymike Wed, 25/11/2015

Well the engine is back in one piece after a good internal flushing. I found out later that the timing gear should be able to be removed with an extractor with thin feet as there is not much room behind the gear. I had to make a new slotted brass link that pulls up the decompression lever as the old one had been brazed up badly. Compression now read around 160 psi on my gauge although actual pressure is probably lower than this figure as I had well oiled the piston rings before fitting.

I now have good compression, good spark and fuel, but it still does not want to start. It very nearly starts on first kick, but after that it get progressively worse.

I noticed that the mixture screw has a damaged end, so I will cure that on the lathe.

The spark occurs a fraction before TDC which I understand is correct.(I checked that with a strobe light.)

Although the carb is now clean, I am not sure if there is the correct "spray" of fuel going into the engine, so might try and encourage that with a compressed air jet.

Any other thoughts/ideas on this would be most welcome.

I have now removed the bottom blade, which has worn out and I had to drill out all 10 of the screw holes. So far I have only removed two of what is left of the original bolts. I will probably have to helicoil the rest.   (5/16" BSF )

So press on regardless. Mike

 

wristpin Wed, 25/11/2015

Immediate thought  - is your "good spark" at the right time? Do you have a figure either in degrees or amount or piston travel before tdc. May be that your "fraction" needs adjusting?

If the action of the descending piston and the valves have created a low pressure area in the carb venturi, atmospheric pressure should do the rest  - supercharging should not be necessary!

sparkymike Thu, 26/11/2015

Hi Wristpin,

Info on the Jap engine is very sparse on the net. For timing, only figures I have found so far are 1/4" before TDC and 1/8" before TDC.

The 1/4" figure was from the Jap engine, as fitted to a Howard rotovator. This was a 600 cc engine. My engine is a 350cc.

I have to divert for a couple of days, as I am also repainting the frame and forks of a 20's motorcycle and that has priority after she who must be obeyed !!

 

Mike.

wristpin Thu, 26/11/2015

1/8 sounds more likely but that's a guess!  Presume that if you are into old bikes with platform mags and impulse units you are conversant with the timing procedure - tripping the impulse and turning the engine back wards to set the timing - probably more familiar than me !!

sparkymike Fri, 27/11/2015

Hi Wristpin,

No impulse on this Wico type A mag, and it looks to be original setup.

Mike.

wristpin Fri, 27/11/2015

Straight forward setting then. If a spark is present when under compression a squirt of fuel into the cylinder via the plug hole should at least produce a single firing. If you can get that, it's then " just" a case of getting the carb to co-operate! 

Get everything right and then " catch it by surprise" as one of my early mechanical mentors used to say  - sadly no longer with us.

 

sparkymike Sat, 12/12/2015

Trying to start the mower the other day, and the kick start spring broke in half !!

I found a very similar one on E bay ,but for a 1950's Atco. The original spring has three coils with inner diameter  around 1  1/8" which is same as new spring.  However, one end of the spring is a straight 2" section same as original, but the other end is not the same as original and has a sort of hook on it. Can anyone post a photo of the 1950,s type kick start assembly, as I will have to make a different anchor and details of how Atco did it would be very helpful and save me a bit of time..

The engine actually ran for around three revolutions before it coughed and gave up, so now I have adjusted the timing slightly.

Until I get the kick start sorted, I will not know the results of my labour.

Mike.