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Collection, Preservation and Display of Old Lawn Mowers

Suffolk Colt, none starter.

I have been given this Suffolk Colt for nothing otherwise it was heading straight for the scrap yard. As and when it was last used I cannot say but it is an opportunity for me to learn how these types of machines work and how to maintain it.

I have fitted  a new pull start, new spark plug, waiting on the replacement throttle cable, the oil level is good, it looks relatively clean not black which is a good sign, I have added fuel to the tank and attempted to start, after a few attempts "Nothing" There is a spark from the lead, there is compression and yes I did turn the fuel tap on and press the primer.

At this point I would like to ask, what is the next  step?  to get it started, all advice would be well received bearing in mind this is my first engine driven mower, I would like advice on how to clean the Carb please.


wristpin Tue, 08/09/2020

Bonus - It’s even got the blanking plate in the end of the dog clutch !

You don’t mention cleaning the carburettor , almost essential for a machine that has been standing . Also you may have put fuel into the tank, but is it arriving at the carb? Pull the pipe off at the carb end and turn the tap on.

If you have an aerosol of carb cleaner , pull tha air cleaner off and give a couple of squirts up the venturi. If it fires then it almost certainly needs a clean.

If you look back over Redleader’s epic post of his Suffolk restoration you will find lots of useful stuff.

John.Sutherland Sat, 12/09/2020

 I used a carburettor spray as directed but it remains a none starter. I will shelve the mower for a next year project,

Redleaders work on his lawnmower is epic, quality work from start to finish,   

John.Sutherland Sun, 20/09/2020

Had some guidance from my neighbour who is pretty good with engines,  we removed the relevant parts to inspect the Magneto and found the cause to the starting problem, there is slight damage to the crankshaft where the Key sits for the magneto flywheel and the key it self looks slightly chewed.

 May have been a result of a loose nut at some point or not fitted correctly, please correct me if wrong - if the Key is worn and does not sit well, does this result in a failure to bite the flywheel as a solid action?  thus creating a weak spark. (I am new at this so still learning).

After reassembling,  the first two pulls the engine tried to start but the issue returned - a failure to start.

we agreed this is the cause and failure to start the engine, I also observed that the Fly wheel when turned by hand is off, the only way I can describe it is - like a buckled wheel, is this an indicator that the crank shaft is either bent or a  balance problem?

I would like advice as to how or what needs to be done next, whether to find a replacement engine or just the affected parts, my experience is zero but I really want to learn and fix the issue rather than run away.

wristpin Sun, 20/09/2020

It’s unlikely to be a bent crank but there’s always a first time. Remove the flywheel and spark plug and see if you can wrap a bit of cord around the back of the centrifugal clutch and the rotate the engine while you or your assistant observes the end of the crank and checks for wobble.

With no key in place does the flywheel sit firmly on its taper? You comment about “slight damage” to the key and crank  keyway but what about the flywheel keyway?

John.Sutherland Sun, 20/09/2020

That is a question I can not answer without first repeating those first steps I took this afternoon, I will look again either tomorrow after work or the days that follow.

I will record a short footage showing the fault, that way you are getting a clear idea than a still image.

I had not planned to touch the lawn mower until next year but my neighbour offered his time and his knowledge on engines is a benefit as I have none.

Not too far away from my location is an ebay seller who has 2 partly stripped Colt engines, one of which may serve as a donor, so your opinion will be the decider as to whether I break mine down to rebuild the replacement which is not complete.

I suspect this fellow has used both engines to rebuild a third which is working and also for sale but it has issues not wanting to start when hot, if he cant resolve that issue, it probably serves as a warning.

Will keep you posted and thank you for your guidance 



wristpin Sun, 20/09/2020

I should have suggested that before you pull the magneto apart, test for a spark. Remove the plug and lay it on an unpainted area on top of the engine and pull the rope briskly . If you see a spark , despite the key damage, you have life. No spark, remove the plug and plug cap from the lead and carefully hold the end of  lead about 5mm from unpainted metal and pull the rope. A spark then suggests either the cap or the plug is the culprit. 

No spark , or an intermittent one indicates an issue with the contact breaker points, or the condenser or the coil/ht lead. A word of warning if you ever consider mixing and matching components from two engines: early engines had a different flywheel and a different taper on the crank compared with later ones.

As usual, an image or two of the magneto with the flywheel removed will assist. 

John.Sutherland Sat, 26/09/2020

I have not been successful getting the two short videos uploaded from my apple phone to accompany the still pictures and for the time being pictures is all I can offer with a description.

No help today that incudes a  lack of interest from my teenage sons and makes following your instructions impossible. 

The key is worn and quite possibly the Keyway, the key it self sits at a slant until I reposition it and even then it appears loose.

The key for a short period sits in the fly wheel housing ( if that is the correct term) during and after reassembly, I may only get a few tugs on the pull start with the engine showing signs of starting followed by a clanking noise - it sounds like one metal object smacking against something else, it  does not sound like a normal part of an engine turning over process.

The key then looses the function and the engine becomes none responsive, the clunking sound also stops,  I can only guess the key has moved position and fails to hold its self correctly. 

 This is not going to be an easy fix, that includes getting like for like doner parts similar in age.

hortimech Sat, 26/09/2020

There is technical term for that crankshaft, key and flywheel, but I am too well brought up to to mention it ;-)


wristpin Sat, 26/09/2020

Looks like the crank is damaged enough that the flywheel will not fit snugly on the taper and therefor will never stay tight. Looks as though due to having been run loose etc it has been "flogging" enough to raise metal around the crank shaft keyway and is past the stage where a new key will give a quick cure. Realistically I think that you need to look for a better engine or better crank.  That's not to say that if it were a life and death situation to get it running it couldn't be fixed but, with respect, I suspect that you don't have the knowledge or the wherewithal. 


John.Sutherland Sat, 26/09/2020

I have looked on line and found what could be a suitable replacement and for the first time I can see how the key way is meant to look.its worth the gamble.