Ransomes MG5 – My latest project!

[vhgmcbuddy]

Hi Guys,

Thanks for the tips. I’ve been in touch with Neil and he is able to supply me with a diaphragm, which is good news. 🙂
That hopefully will allow the delivery of fuel to the carb. It is strange that there is no evidence of a TVO tank. So yes, I assume it will run OK on petrol..

Does anyone have any advice on things I should check with regards to the magneto? It does seem to spark, but perhaps not every time when turning over.

Cheers

James

[vhgmcbuddy]

Hi all,

Just a quick post to say that after some help from Neil I finally managed to get the old girl running this weekend. Was a bit of a challenge. Major fuel system overhaul. First stop was to strip and clean the pump and fit a new diaphragm. Strangely this did not solve things. So, to test the pump I ran a pipe from a jerry can. No problem lifting fuel, so I checked the tank and fuel pipes. It turned out the fuel pipe was blocked and the tank was full of rust. I ended up removing the tank for cleaning and blowing the pipe through with an airline. Sorted!

I changed the oil as suggested and fitted a new plug. She fired up no problem and ran OK. Although the manifold is blowing a bit! My main problem is the carb (which I’ve also had to bits and soaked in fuel), mainly the float needle. It doesn’t seem to be cutting off the fuel. Hence the bowl is over filling and leaking. Should there be a gasket between the bowl and carb body??

Or can you buy new new float needles?

More info and pictures tm!

P.s. Its very loud!

[vhgmcbuddy]

There should be a gasket between bowl and body, there is a cut out for when you flood it so it may be coming from there?

The needle seat may be at fault, it may need lapped in or a new seat and needle.

The float may have a hole in it, does it float?

Neil does standard and longer needles and used to fit seats.

The vibration of the engine often knocks the needle off it seat causing excess fuel to flow out of the bowl.

[vhgmcbuddy]

Great. Ok I will order new needles and gaskets from Neil. I’ll need to check the float – actually floats! Good thinking. Yes it does vibrate A LOT!

What are peoples views on this carb I have? Is it worth holding onto? I never intend to run with TVO, so can I swap out the manifold to get better performance from it? Is it really worth it?

A few pictures from the weekend.

Cheers

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[ransomes256]

James,
The carburettor is generally considered the better version as it has mixture control.
To get the engine to run sweetly it is important that the air inlet pipe is fitted and air tight plus the correct oil in the filter. Without this the air flow rate across the venturi can be higher than expected and therefore the mixture control is poor.
Neil

[vhgmcbuddy]

Ok. Great. Thanks Neil. I’ll get some clamps around that hose. I’ve checked that the oil is at the correct level in the filter. I presume the screw knob on the top of the carb is the mixture screw. Very basic these things. Love it!

[vhgmcbuddy]

James,

I didn’t realise you had the later Amal caeb, the above information I gave may not be relevant!

[vhgmcbuddy]

Hi all,

I’ve hit a bit of a stumbling block with the Ransomes recently. Mainly resolving around getting it to start. 🙁

I did manage to get it running for the first time last weekend, but even then it wasn’t a simple operation to get it started. It would take 10-20 goes to get the thing to almost start before actually starting.

At that time the carb bowl/carb did not have a gaske, and the float needle wasn’t cutting off the fuel, so it was over-fueling some what.

I have since ordered the correct gasket and float needle from Neil and seem to have cured this problem.I fitted these yesterday. I did also order a new Main Jet and Pilot Jet from Neil.

Looking at the parts diagram for my carb. Part No: B120 is the mainjet, and 124/026 is the Pilot Jet. I went to install these yesterday, but my Mainjet appears to only be a brass nut? I removed the Pilot Jet plug screw, but did not actually change the pilot jet (I’ll need to take the carb off the vehicle for that). The Main Jet from Nel was too small dia to thread into what appears to be the Main Jet hole that my nut came from, but did indeed fit into where the Pilot Jet Plug screw came from..

Fast forward a little ALOT of attempted starts it eventually fires up. I run it for a 5 minutes or so before turning it off. And now I can’t seem to start it again.

Bearing in mind it was never a good starter I am now looking to find out exactly what is wrong, and hence I have a few questions.

What I’ve done to the MG5

A) Brand new correct spec plug fitted. The gap was around 0.015-0.020″ when new. Upon removing the plug it was extremely black! I’ve consulted the manual and opend the plug up to 0.030-0.035. Now when attempting to start it seems to try and backfire.

B) New float needle & gasket in carb, plug jet changing as above. Confirmed that the float does float.

C) Overhauled fuel pump and tank. Fuel supply is certainly not a problem!

D) Confirmed the magneto is working. It sparts to the block when you turn the handle. HT lead is also good at both ends. I am reluctant to remove the magneto and check the points since it has actually run OK on a few occasions, if a little rich..!

E) Fresh engine oil change.

Questions

1) Am I starting it using the correct method?

I am doing the following.

a) Disconnect HT lead
b) clock the choke
c) Turn over 3 or 4 times to draw in some petrol
d) Open choke, push throttle partially open.
e) Rotate until I feel compression then pull over hard.

Note: I don’t always hear the special ‘cick’ from the magneto when turning over. Is there a trick to this? Should I be turning it over harder/faster? What exactly is this click and what instigates it?

Personally I believe that I am starting it by chance conditions in the combustion chamber through flooding and repeated attemps, which can’t be right.

2) Is this TVO manifold causing me a problem with a petrol setup?

3) Should I put the spark plug back to 0.020? – Surely this should not prevent me from starting it.

4) How many times/how long does it take others to start their MG5?

I’d be grateful for as much feedback as possible as I intend to take the vehicle to a show next weekend and would like to have it running before hand..

James

[charlie]

The click from the magneto you refer to sounds as if the magneto has an impulse mechanism. This is operated by a spring which is wound up as you turn the magneto and trips to spin magneto faster than you are turning it. This gives a bigger spark for starting, when running the impulse does not operate.
In your list of what you do step a) disconnect HT lead. I dont see any step where you reconnect it!

[vhgmcbuddy]

HT lead us reconnected after step C.

Should the magneto click after every rotation?

James

[ransomes256]

James,
The click is the impulse of the magneto which should be heard every time when cranking by hand.
The actual impulse is there to retard the ignition by about 20 degrees to make starting easier and also flicks the rotor faster to improve the spark. If the ignition is not retarded it will make starting virtually impossible. When the engine starts the impulse pawl moves away due to centrifugal action and therefore advances the ignition.
If the mechanism is sticky you will need to remove the magneto and clean it. Mark the flange mounting then turn the engine until you do get an impulse click. Do not crank the engine any more. Remove the magneto, clean and check points. Before re fitting rotate magneto by hand until impulse releases and then refit with the nearest dog position to the marks as previous.
Neil

[vhgmcbuddy]

Hi Neil,

Thanks. Hopefully this is the route of the problem. Is this an easy job? Can I clean the required parts without fully stripping the magneto?

[ransomes256]

James,
It will depend on if everything is as it should be and nobody has been there before.
Often some aerosol brake cleaner or similar sprayed around the release mechanism will do the job but if the spring has gone weak it may need to be wound on 1/2 a turn.
With the points just make sure the insulator strip covers the entire length before you put the cover on.
Neil

[vhgmcbuddy]

Hi Neil,

Well, I remove the magneto from the engine yesterday. Carefully marking it’s position before removing. The pulse spring seemed to have resonable force and would spring back when the pawl was engaged. It looked reasonably clean, but I cleaned it out and applied a light smearing of 3 in 1 oil just to be sure.

I’ve refitted it – hopefully not 180 degrees out if that is possible?

However still no joy getting her to fire up.

Back to the carb and I decided to completely remove and fit the new pilot jet. (I’d already fitted the new main jet on Friday).

I enclose a picture of the damage/wear that I have discovered around the pilot jet area. I have cleaned this off and applied some araldite in the hope of making good.

Removing the old pilot jet was quite tricky, and it was obviously in a bad/gummy state.

I am however a little confused why the there woule be a screw threading into the end of the pilot tube blocking it off? (Threaded into the damaged part)

Would this pilot jet prevent starting? Is this not the equivilent of the idle jet on a modern carb?

Cheers

James

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[ransomes256]

James,
The jet is fed via one of a number of cross drillings in the carburettor body. These are blanked and may be blocked causing your starting issue.
Neil

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