Mountfield Lawnmower - a first for me

[pycoed]

My son dropped off his Mountfield lawnmower with a B&S Sprint engine - the one with a plastic carb on top of the tank - which wouldn't run despite the administrations of himself & a neighbour.

I remembered having bodged up the diaphragm with some elec tape a couple of years back, telling him to buy & fit a new one...
So of course when I found the red tape showing under the carb, cursing the son & heir, I just ordered a new gasket & diaphragm, so began the saga:-

1 Carb diaphragm was knackered - renewed with new gasket
2 Carb O ring seal to inlet manifold was iffy - renewed
3 Carb "bowl" was dirty - in top of tank - cleaned out
4 Dismantled carb & cleaned all jets - a masterpiece of value engineering actually
5 Checked coil - was slightly rubbing on flywheel - reposition & set clearance
6 Check plug for spark - fine
6 Still wouldn't effing start
7 Have a good think - plug was soaking wet...
8 Look for different plug - only one found that would fit was an old Kohler 8hp plug.
9 Check Kohler plug for spark - OK.
10 Fit Kohler plug
11 It starts!!!
12 Cut grass -OK but it won't shut off, so pull plug lead to shut down
13 Fix cable shut off so dead man's handle works.
14 Cut some more grass - all fine & shuts down properly.
15 Write out bill to send to son

Now, I've messed about with engines of many sizes since about 1964 & never have I found the issue to be the plug(s). Everyone always says - "Oh! Change the plugs first" but I repeat I have never had a faulty plug. Caps, leads, distributors, coils , points, CDI units, sensors? yes by the bucketload, but this is the first time in 56 years I have personally found the plug to be the issue. I even have a Danarm brushcutter bought new in 1979 with a Kawasaki 35 ish cc engine that is still on the original plug. Ditto Wheelhorse tractors from 1970's. That'll learn him for putting a Briggs & Scrap'em genuine plug in it

 

[Henarar]

chainsaw wouldn't start the other day, messed about with it for half hour with no luck swopped the plug for the one in the other saw at away she went, couldn't see anything wrong with the plug

 

[Mur Huwcun]

I wasted a few hours yesterday with the flipoing lawnmower! It had a hizzy fit over the weekend when cutting around our entrance and started hunting and surging! Governor linkage was erratic so managed to wedge it at a desirable speed to finish the job. Now, I was given this mower as a non runer but got it going by sticking the choke linkage back On!!

Started off with carb off for a clean. Nothing wrong with it but gaskets were iffy so made two new ones!! (Should be in quick bodges thread, fikter box and ball pein hammer).

Re fitted everything, it started better but still the same!! Tried wd40 around gaskets just in case so re set governor linkage just in case, still the same so in the end just left it!! Flipping lawnmowers, may try again tonight!!

 

[stroller]

My son dropped off his Mountfield lawnmower with a B&S Sprint engine - the one with a plastic carb on top of the tank - which wouldn't run despite the administrations of himself & a neighbour.

I remembered having bodged up the diaphragm with some elec tape a couple of years back, telling him to buy & fit a new one...
So of course when I found the red tape showing under the carb, cursing the son & heir, I just ordered a new gasket & diaphragm, so began the saga:-

1 Carb diaphragm was knackered - renewed with new gasket
2 Carb O ring seal to inlet manifold was iffy - renewed
3 Carb "bowl" was dirty - in top of tank - cleaned out
4 Dismantled carb & cleaned all jets - a masterpiece of value engineering actually
5 Checked coil - was slightly rubbing on flywheel - reposition & set clearance
6 Check plug for spark - fine
6 Still wouldn't effing start
7 Have a good think - plug was soaking wet...
8 Look for different plug - only one found that would fit was an old Kohler 8hp plug.
9 Check Kohler plug for spark - OK.
10 Fit Kohler plug
11 It starts!!!
12 Cut grass -OK but it won't shut off, so pull plug lead to shut down
13 Fix cable shut off so dead man's handle works.
14 Cut some more grass - all fine & shuts down properly.
15 Write out bill to send to son

Now, I've messed about with engines of many sizes since about 1964 & never have I found the issue to be the plug(s). Everyone always says - "Oh! Change the plugs first" but I repeat I have never had a faulty plug. Caps, leads, distributors, coils , points, CDI units, sensors? yes by the bucketload, but this is the first time in 56 years I have personally found the plug to be the issue. I even have a Danarm brushcutter bought new in 1979 with a Kawasaki 35 ish cc engine that is still on the original plug. Ditto Wheelhorse tractors from 1970's. That'll learn him for putting a Briggs & Scrap'em genuine plug in it

I've got a Honda water pump, it started cutting out at high revs, and was difficult to start just like fuel starvation, I cleaned the fuel system, still no luck, after putting a new spark plug in it ran perfectly. Maybe modern spark plugs don't last as long

 

[tomlad]

Simular honda mower
Intermittent cut out , blah .....

New plug sorted
Just make sure u bin the old plug , keep as a pattern, then forget y its out , .......

 

[TripleSix]

Always try a new plug first.
Easiest...

Honda and Briggs ohv plugs are NGK BCPR5ES or BPR5ES 6's are fine too

Most 2 stroke stuff is NGK BPMR7A

I tend to put the short reach Briggs plugs in the side valve Briggs.
They were champion CJ6 I think
Can't remember NGK equivalent

 

[br jones]

As above ,plug first these days ,darn things show spark but pop it in and nowt fff things

 

[manhill]

Blew the engine apart on my B&Q petrol mower. I couldn't believe how thin the cylinder alloy was.
Looking for a decent 240v one now.Happy to put up with an extension cable rather than bugger about with the problems petrol one's throw up.

 

[TripleSix]

Blew the engine apart on my B&Q petrol mower. I couldn't believe how thin the cylinder alloy was.
Looking for a decent 240v one now.Happy to put up with an extension cable rather than bugger about with the problems petrol one's throw up.

Cordless is the way to go

 

[manhill]

Cordless is the way to go

240v will run all day long at rated power, battery type are a bit of an unknown until manufacturers produce power/time charts.