Two Stroke Flymo - JLO Engine

[aesmith]

Hi,

I was wondering if anyone knows about these beasts, it's an oldish Flymo with two stroke JLO branded engine.  I can't put an age to it but the deck is plastic which might suggest not really old.  It's exactly like this one except mine isn't so clean ... https://youtu.be/Kn0IdqVCgr4

 

I started having problems last year, sometimes it would falter when running and need to either have the choke flipped on or a jab or two on the tickler before it would pick up.  So looking like some sort of fuelling problem.  To be honest I kept meaning to investigate, but couldn't work out how to get the carburettor off so I kept putting it off.

 

 

This year after a period in storage it won't start at all, not even the slightest indication of firing.  Plug is sparking nicely, compression more or less as I remember from last year, new fuel but not a peep.  Pulling the plug it's suspiciously dry even after a good few pulls.  So I've bitten the bullet and taken the carb off, that involves removing the blade and fan, separating the motor from the deck and then unbolting the white "thing" that's bolted onto the underneath of the engine and has the effect of preventing the carburettor from coming off.

 

I've stripped the carb and not really found anything that looks wrong except a small bit of something in what I think is the main jet.  The one that screws in from the bottom of the float bowl.  That could be the culprit but it really didn't look like it would have completely blocked it.  All other jets and passages looked clean and I've blown through everything to make sure.  Essentially it's ready to go back together.

 

Anyway given the amount of dismantling needed to reach this stage I thought I'd see what people think before putting it all back together and maybe finding it has to come apart again.

 

Thanks, Tony S

[adw]

Good lord not seen one of them for 40 years when I worked for a garden machinery dealer, the engines were used a lot on badger cyanide pumps, anyway y Es it is just fuel starvation, as I recall the crank was a three piece thing that twisted if you hit something hard, the only have a small flywheel so rely on the blade as a flywheel, so make sure the blade is real tight, good fue flow from the fuel hose with tap turned on, as you have now cleaned the carb I guess it should fire up ok.

[aesmith]

Cheers, do you happen to remember what fuel/oil mix they used?  The guy I got it from said 25:1 but I think he might have been misreading the mark on tank which is actually 1.25L

 

I put it back together this morning and it seems to run OK now, so I guess that tiny bit of grot must have been the culprit.  I think it's had some abuse in the past, the key for the fan was sheared off for example and the bolt through the blade and fan is a bit damaged by someone using the wrong size spanner (partly excusable as it uses a mix of imperial and metric fasteners).  It's got the wrong blade as well, sharpened to suit a machine turning the other direction and with a rough edge put on the correct side.

 

The data plate says 3,800 rpm, it was running much slower than that but it's fiddly to adjust so I left it just around 3700 and it certainly hovers better than before.

 

Needs new fuel pipe and there doesn't seem to be any sort of filter so I'll fit an inline filter in the fuel line.  If it carries on running OK I might treat it to a new blade as well.  Too wet at the moment to actually cut any grass.

 

After fiddling with it running I now absolutely stink of two stroke exhaust.  Unfortunately the brute is far too gutsy to consider running on Aspen,

 

 

[waterbuoy]

I still have one - with the original Flymo mixing bottle - and it is supposed to be 25:1

[aesmith]

Cheers.  I've got one of those bottles as well.

[Sawchip]

1 hour ago, aesmith said:

Cheers, do you happen to remember what fuel/oil mix they used?  The guy I got it from said 25:1 but I think he might have been misreading the mark on tank which is actually 1.25L

 

I put it back together this morning and it seems to run OK now, so I guess that tiny bit of grot must have been the culprit.  I think it's had some abuse in the past, the key for the fan was sheared off for example and the bolt through the blade and fan is a bit damaged by someone using the wrong size spanner (partly excusable as it uses a mix of imperial and metric fasteners).  It's got the wrong blade as well, sharpened to suit a machine turning the other direction and with a rough edge put on the correct side.

 

The data plate says 3,800 rpm, it was running much slower than that but it's fiddly to adjust so I left it just around 3700 and it certainly hovers better than before.

 

Needs new fuel pipe and there doesn't seem to be any sort of filter so I'll fit an inline filter in the fuel line.  If it carries on running OK I might treat it to a new blade as well.  Too wet at the moment to actually cut any grass.

 

After fiddling with it running I now absolutely stink of two stroke exhaust.  Unfortunately the brute is far too gutsy to consider running on Aspen,

 

Those jlo units are still sought after on the GT hover...the Tecumseh MV 100s is a another ok 2 stroke but the carb location is a right pain compared to the jlo. Had to bring a Allen pro hover with a mv on it from moth ball ...what a pain to just remove the carb.

The MV will run on modern synthetic oils at 50: 1 ...in the service book.... (40:1 my pref) and as the jlo was 25:1 spec  with old sorts of oil I would say you should be fine with less than 25:1. Carb was fixed jet on the MV, is your jlo carb ? re tune for different mix if not a fixed jet. 

 

 

 

 

Edited May 17, 2020 by Sawchip

[aesmith]

19 hours ago, Sawchip said:

Tecumseh MV 100s is a another ok 2 stroke but the carb location is a right pain compared to the jlo

I actually thought removing the carb from the JLO was a pain, I dread to think what the MV is like.  To separate the carb I had to .. remove blade and fan, unscrew engine mount from the deck and remove engine and mount from mower, unbolt engine mount from bottom of engine, remove fuel tank and top cowling to disconnect the governor vane.  I did wonder about cutting the engine mount so the carb can be removed with the engine still installed, but haven't gone that far.

 

As far as I can see the carb isn't adjustable except possibly by installing different jets.  There's a single screw which I believe is supposed to be idle mixture, but that doesn't do anything as the engine never idles.  There's no throttle control, it always runs at full governed speed.

[Khriss]

They were good mowers fr banks , culverts. K

[aesmith]

That's exactly what I use it for, slopes too steep for a normal mower.  Only option other than two stroke would be electric.

[openspaceman]

50 minutes ago, aesmith said:

That's exactly what I use it for, slopes too steep for a normal mower.  Only option other than two stroke would be electric.

I've still got two and chose them as they don't seize on steep banks, mind I don't think I have used them for 30 years other than to see if they still work. I cannot remember if they are aspera or tecumseh engines.