Ransome Triple Mk4 pertol Mag engine help won't idle

Tagged: ransome triple MK4 Mag petrol idle problems

This topic has 32 replies, 9 voices, and was last updated 8 years, 6 months ago by vhgmcbuddy.

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May 26, 2016 at 6:50 pm #20970

vhgmcbuddy
Member

Hi all,

I’m new here so i thank you in advance for any help you can give me.

We have just brought a new house with over an acre of land and in the undergrowth we’ve found a Ransome Triple Mk4. I’ve freed up the brakes and managed to pull it out of the undergrowth put some oil down the bores and it turned over freely, fresh petrol and jump started it and it started first time!
So I’ve spend numerous evening to date now i’ve rebuilt the 4 brake calipers,
Replaced the centrifugal clutch shoes as the linings had detached,
cleaned out the fuel tank, glass bowl filter and carb fuel filter,
fitted a new fuel pipe,
taken the carb apart cleaned out the main jet in the center and what i think is the air/mixture screw.

My problem is it won’t idle so that the centrifugal clutch disengages, it run fine at high revs but if i try and adjust the throttle stop on the carb it just stalls before the centrifugal clutch has slowed down enough to disengage. I’ve spent quite a lot of time freeing up rusted parts and greasing everything up now and i really could do with cutting the grass as i managed to loose my 18 month old son in the long grass the other day its so long!!

Any photos of other peoples carbs or throttle / governor setup would be great as i don’t know if mine is correct, manuals or document particularly operators manuals or engine info would be really useful too. I’ll try and upload some photos in a bit

May 26, 2016 at 7:04 pm #20971

stuart
Participant

I think you need to clean the carburettor more thoroughly,possibly even get it ultrasonically cleaned.What engine is fitted ??

May 26, 2016 at 7:05 pm #20972
vhgmcbuddy
Member
Here’s a short vid of the engine adjusted as slow at it will go and slower and it just stall, could it be a fault in the carb over fueling the engine even if the throttle is fully closed?
Attachments:
1. IMG_0668_CLIPCHAMP_240p.mp4
May 26, 2016 at 7:11 pm #20974

vhgmcbuddy
Member

Hi Stuart it’s a MAG 2055 SLRX 2 cylinder petrol if that helps. I’ve had the carb apart 3 times now removed all the parts and left it sitting in carb cleaner for a while blow an airline through the various jets and holes and used a tiny piece of wire to clean any pin holes out. I’ve never gone down the ultrasonic cleaning route before i’ve never needed to as the above normally does the trick.

May 26, 2016 at 8:30 pm #20975

joegrgraham
Participant

Have you replaced the clutch springs? They are probably weakened, and that wont be helping with the disengagement.

Joe.

May 26, 2016 at 8:46 pm #20976

vhgmcbuddy
Member

Hi joegrgraham, The place where i got the new clutch shoes gave me a pair of new springs which i have fitted. The only thought i had was are the petrol and deisel engine springs different i.e. does the clutch bit at different rpm? Only a thought.

May 26, 2016 at 8:59 pm #20977

joegrgraham
Participant

I’m not familiar with this particular engine, however I had similar problems with the running on a B & S ZZ with a Flo-Jet carb.
Check the throttle butterfly, is it worn on the shaft? this will allow the butterfly to flop around, causing the poor idle.
Also check that the needles/jets are seated snugly in the threads, if they are loose in the thread this can allow too much air through, causing problems.
Also worth checking that the fuel needle seats properly so you’re not getting too much fuel into the carb at a time.

Joe.

May 26, 2016 at 9:09 pm #20978

vhgmcbuddy
Member

Butterfly’s are all snug no excess ware. i will double check the jets are firmly seated tomorrow it’s getting late to start up with no exhaust. I’m starting to think it’s too much fuel as when i rev the engine it takes a minute or 2 to slow down again pointing to over fueling?

May 26, 2016 at 10:04 pm #20979

stuart
Participant

If the engine takes a little while to slow down after being revved (and its not just the large / heavy flywheel effect) it points to a lean mixture caused by an air leak.Check cylinder head gasket(s) and carburettor inlet manifold gasket(s).Worth checking valve clearances and ignition timing while you are at it too.
Over fueling (rich mixtures) are evident by black exhaust smoke and sooty / black / fouled spark plugs.

May 27, 2016 at 7:29 am #20980

charlie
Keymaster

If the carb has had water in it then you could have problems caused by corrosion, see my post Walbro carb . As your engine runs OK at high speed but not at idle it might be worth checking the slow running jet is clear and set correctly.

May 27, 2016 at 8:20 am #20981

vhgmcbuddy
Member

I’m a little confused by this MAG carb there are only 2 adjustment screws, one on the air filter side near the choke butterfly that I think is the air mixture adjustment, and the other by the throttle on the engine side that appears to be the throttle stop. If I wind the 1st one all the way in and out it makes no difference to the engine running, even if I remove it completely. The 2nd one just adjusts the tick over, too far one way and it stalls unless you blip the throttle. Any pictures or manuals for this carb would be really useful. I’m starting to think it has to be a carb issue. I’m going to stop by an old agricultural machinery agent John O’Connel I think its called in Codicote this afternoon and see if he has any spare carbs I can swap out to rule this out

May 27, 2016 at 6:56 pm #20984

andyfrost
Participant

By your above post , it would suggest a blockage , have it cleaned in an ultrasonic cleaner.

Andy.

May 28, 2016 at 6:00 pm #20987

trusty220
Keymaster

These engines had two types of carburettors fitted. When I was working on them full time they were simply known as “Old Type” and “New Type”; it does rather sound like you have a blockage of the slow running jet, but if you say you’ve cleaned it then I don’t doubt you.

I’m just using a bit of lateral thinking here- have you set the points to the right gap, and is the ignition timing set correctly (by turning the distributor)? If the points gap is too small the first sign is that the engine won’t run on tick-over. I’m a little puzzled by the engine running on as well because they used to shut down quite quickly when the throttle is released; have you tried re-setting the governor?

The video that you posted would suggest that the engine is running at it’s normal working speed, ie full governed speed, and it should not go any faster than that. Have you any idea on the rpm that it’s doing on the video?

May 29, 2016 at 11:58 am #21031

vhgmcbuddy
Member

I’ve just removed part of the engine shroud to clear out the squirrels nest in the cooling fins and removed the crankcase breather. When i then turn the engine over by hand there is a lot of crankcase pressure, does this point to a head gasket or valve stem seals letting by? I will remove the head later and see if i can see any signs of letting by. Any idea where i can get a new head gasket from?

May 29, 2016 at 8:05 pm #21032

wristpin
Participant

If you are just turning the engine over by hand there’s a fair chance that your “pressure” is just the air in the crankcase being displaced by the descending piston.
For a head gasket try Paul at Meetens
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