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Collection, Preservation and Display of Old Lawn Mowers

Ransomes 24" Mk8 mower


Firstly it's great to have found not only this wonderful website, but also an active forum here too, that hopefully can help me!

I recently discovered in a local farm auction sale LOT 730, this rather fine mower in superb condition made by Ransomes (which the side plate seemed to suggest was a Mk8) ...but when searching the internet for information...... very little was found, except for stumbling into this forum and the related Mk4 forum post that finally looked rather like this one!

Anyway, I'm very pleased to say that I did win this Mk8 at the auction for £75 (maybe a bargain, or not!!) but would really appreciate help with not only how to get it running as the fuel tank seems to have two fillers, (I assume one is for the 2 stroke petrol mix...but would that be 25:1?) and the other I guess is for oil, but again what type?

The cooling fan's cover appears to be missing, however as getting a replacement is likely to be impossible I'll just have to watch my fingers keep well away from that (!), but could anyone who possibly knows about these fine machines give me step by step guidance as to any pre-check tips for this mower..... and then how actually to start it up, without damaging anything on it, or indeed myself in the process!

Thanks in advance ....and lastly what date would this mower be?

I was expecting such a fine machine to go much higher than 75, however it really is a huge heavy mower, so maybe that's why it didn't go any higher?

It also came with a trailing roller seat (which I'm not sure if that's an original for it, or just was an 'add-on' by somebody) but it's hopefully all going to be running again soon... with your help.


1man_went_to_m… Tue, 30/11/2021

Researching more on this mower it appears to have a (1931?) Sturmey Archer 348 cc engine and this drawing was luckily found via Sturmey Archer Heritage:

It has a very advanced (for its time) dry sump lubrication system, but due to most search engines these days being totally useless (!) I've been unable to find out what is the best type of oil to use... so I'm going to stick with good old SAE30

The tank on the mower is of dual compartment, with two fillers - one side is for the engine lubrication oil and the other tank's compartment is for just petrol, not an oil+petrol mixture as originally thought!

This is then like vintage Howard Gem rotavator etc, that also have the dual capped separate tank compartments.

One doesn't mix the oil and petrol, because it's a four stroke engine (not a two stroke) and the separate tank compartments are for that purpose since the engine has no actual sump for lubrication, the tank is in effect the sump.

From a manual the Howard rotavator says: 'Fill the oil tank to within 1" from the return pipe inside the tank and remove the filler cap frequently to see the oil is circulating through while the engine is running. If the oil should drop below one-third full fresh oil must be added'

I have also discovered the mid mounted lever on the handle cross bracing is for decompression, as the crank handle is much easier to turn, with the lever held in!

Taking out the spark plug I wanted to test and see if any spark was being generated.

The answer YES! ...a huge zap of blue across the plug's gap, so there's certainly no problem there!

I bet then this engine could give rather a nasty kick, if improperly started.

So anyway having now sorted out fuel and oil I found the petrol tap off/on plunger was very loose and checking it revealed the internal cork has gone dry and thus shrunk, so there's no point just filling up the fuel tank yet...because it would leak everywhere.

A good tip here (for any dry corked fuel tap) is to simply remove the tap's plunger (usually by unscrewing the tiny screw slightly) and put the plunger unit complete into a small metal container with a tiny amount of petrol covering it, to thus soak and swell up the cork.

This I've done and so will wait for that to happen.....

When it does I'll be able to put the plunger back again and test fill the tank with a little bit of petrol on that side, to see if the fuel now won't leak.

Meanwhile I'll fill the oil side of the tank with SAE30 to within 1" from the return pipe inside the tank.

1man_went_to_m… Sat, 11/12/2021

Just a quick post to update on this thread:

Fuel tap cork took about 3 days to swell up (and so is back in the tap's sleeve nice and tight), so it all works great again (with no fuel leaks, ON or OFF) so that's good! The oil tank was filled with SAE30, thus everything is ready regarding that, however the weather has really taken a turn for the worse - so the mower is just sitting in the barn right now.... waiting for dry conditions outside, for any test run.

villiers98 Sun, 12/12/2021

I had a Mk8a for a while which was the post war? updated version. This had an impulse magneto so was easy to start, with care. Cant see magnet clearly but think this is a conventional one.

1 There should be a sump drain bolt -  just check the missing oil has not turned engine into a wet sump version by draining any oil in sump

2 Make sure the brake works before mowing- takes ALOT of stopping

3 There should be 2 clutches - pull out dog clutch on top for transmission case to isolate the cutter drive , and a pull out and turn 90 degrees pin that disengages the reduction gear assembly (  between engine and side casing and looks brass coloured in photo ) Both these should be in the out of drive postion

4 Full choke, flood carb well , use no throttle was the best setting I found

5 Check the starting handle free wheel works ok - 8A did not have this so unsure of details

6 Trailing seat looks like a Dennis one - someone will advise

7 Check valve clearances to safeguard valves - I d guess about 6 and 8 thou

Somewhere I still have a parts book.  The engines are very smooth and quiet, and with a large centrfugal clutch take up drive effortlessly. Dont use too much throttle. Good luck

villiers98 Sun, 12/12/2021

Another couple of thoughts  - this model was made 1936-53 I believe. The engine model was referred to as LSA . The magneto should have a push-to stop button on it. Some form of metal guard bolted to the the fan guard holes would be a good idea before starting.


The larger engine was used on the 30 inch Mk9 and also on the Ransomes MG crawlers at one time.