Christmas quiz - starting elderly 2 stroke gardening equipment

[Nomad]

Hi everyone.
As I have a couple of quiet days I'm doing "fun" stuff and looking at some "when-I-get-time projects

Does anyone have any info, advice, or links to get old 2 stroke motors running again?
All have been in storage for a while. History in unknown so maybe they were working when they were put away or maybe they were scrap. I'm trying to work out which.

Strimmer. I collected this recently as part of a joblot, it looks like a good quality commercial bit of kit so I'd like it working.
Seller told me it was working fine last year (which might or might not be 100% accurate)
The trigger /cutout / throttle has been swapped onto my working strimmer and is fine (so that's not the problem).
A loose carb mounting flange was easily fixed but it doesn't inspire confidence.


Chainsaw - has been in storage for many years.
The make is a vintage Homelite XL, I can find some older videos on You-tube etc saying spares are still available so they used to be worth repairing.


There's also a vintage rotovator, no photos but it's similar to below.
It gave a few coughs and bits of exhaust smoke when I tried to start it, but never actually fired and ran.


All machines have the same symptoms :
I'm using fresh petrol 2-stroke mix (from my working strimmer)
Ignition looks ok with a decent spark (new and known good plugs have been tried)
Carbs have been stripped, cleaned, jets blown through, float valve checked and looks ok.
With the carb off I can see the piston - everything looks used but I can't see any signs of damage.
With the plug out, checking with a thumb over the plughole says all have compression but I'm more used to 4-stroke motors and I'm not sure what "good" would feel like.
I've even resorted to warming the plug on the gas grill, putting a squirt of petrol mix direct into the cylinder, refitting the plug and trying to start it when it's still "hot".

There's no signs of life, no firing or exhaust smoke. Is there anything obvious I've missed?
I know lots of things it might be but have tested everything I can think of.
If you suggest something can you make sure you explain how I can test it using my limited tool kit (no compression tester here)

For background, I have a lot of experience renovating vintage 4-stroke motors but I'm struggling with these.
I'm using a newer 2-stroke strimmer and have no problems starting that even if it's been left for a while.

Have fun and merry Christmas to all

 

[mike 109444]

Check out mustie1 on YT, especially some of his older videos

 

[Richard Stowe]

try easy start

 

[Pete.]

Anything like that the first thing I do is check the fuel line for splits or kinks, especially inside the tank. Don't just rely on a visual inspection either literally pull the lines out and run them through your fingers.

 

[Ross365]

There seems to be times when old two-strokes will refuse to start no matter how much time and energy you spend on them. Good plugs, good fuel, some Easystart and keeping them indoors to try warm them sometimes counts for nothing. I'd love to offer you some brilliant insight but cannot.

I don't think I will ever buy another two-stroke; I'm too bloody old for that sort of problem.

 

[Chippie]

2stroke engines rely on good crankcase pressure/vacuum…..if the crank seals are perished it won’t run….

 

[Mick Annick]

There seems to be times when old two-strokes will refuse to start no matter how much time and energy you spend on them. Good plugs, good fuel, some Easystart and keeping them indoors to try warm them sometimes counts for nothing. I'd love to offer you some brilliant insight but cannot.

I don't think I will ever buy another two-stroke; I'm too bloody old for that sort of problem.

I recently ditched my Stihl FS38 for a battery one, life’s too short…

 

[octo0072000]

what mix you using a lot of the old 2strokes used 20to1 mix nice and oily

 

[Blobber]

Ive found if youve checked the basics and filled with fresh good fuel mix after 10 pulls to get some fuel through leave it for a week ad come back to it, seems to help ungum the carb and loosen the old oil up

 

[James1979]

Have you looked at the gauze filters in the carbs? Obviously make dependent but they’re all much of a muchness.

If they’re not stored properly the fuel evaporates off on the gauze and the residue blocks them. Like limescale.

Logically if you’ve air and spark it must be fuelling. It’s the usual suspect on badly stored engines.

As Pete says check the fuel lines. They can Venturi air in.

Tank filters? They’re weighted. Or should be. Sometimes the weights come off and they don’t pick up properly

Dunno which it is? This book covers a few….

This book is your friend. Happy to email anything from it.

What carbs? Got PDFs of Walbro; Zama and Tillitson if that’s useful?

 

[Bornfree]

Take the air filter off pour a little 2 stroke mix into the inlet and try to start it with no choke and full throttle.

 

[James1979]

Take the air filter off pour a little 2 stroke mix into the inlet and try to start it with no choke and full throttle.

+1

Only needs a bit. Finger over the end of a straw type amount

 

[Migmac]

Check out Bruce’s shop on YouTube, think it was an old home lite he’s was working on recently

 

[tom2207]

this is the guy you need ,, watch a few of his videos ,,
clean fuel and you will be laughing
basics though .,. make sure you know how the on off switch should be set too.

 

[addjunkie]

Put in the car, take to tip. Buy battery…… but if masochism is your thing if they been left too long. Carb diaphrams stick together, gauze filters, crankcase seals go britle. Then you get failed coils and various other things.

 

[tom2207]

Put in the car, take to tip. Buy battery…… but if masochism is your thing if they been left too long. Carb diaphrams stick together, gauze filters, crankcase seals go britle. Then you get failed coils and various other things.

pah ,, wheres the fun in throwing them out ,,, once they fire once they may be grand ,,, I make a point of starting my stuff every few months ,,, not so vital on mowers etc ,, but its handy to have the gen set ready to go ... biggest thing there is mark the on off switch , the full tap and the choke once you know where things should be set to get it to go , your in with a fair chance.

 

[Alan Reynolds]

If you have a good spark, is the plug wet when you try and start it? If it’s wet, it could be low compression caused by a stuck ring or leaking crankcase seals if it’s sat for a long time.

 

[Farside]

My Stihl 034 is a sod to start once it's been sitting for a while (like months or a year or two).
The past few times I've taken the plug out, looked at it, pulled the engine over without choke (in case I flooded it) and checked for spark, stuck the plug back in and pulled it over and it fired like it's been given a service. I have changed / cleaned / adjusted nothing.
Totally contrary bastard. After that, it will fire perfectly for endless times until it's left idle again.

 

[Tinbasherdan]

Stick some easy start down it throat and get it running on that, you’ll probably find after 5 mins it’ll start just fine

 

[Nomad]

Thanks to everyone who made suggestions, it's appreciated (especially the ones with links or ways to test the faults)

Update on the "it was working great last time we used it last year" Strimmer

It's alive and twitching (hopefully the next stage will be to get it alive & kicking)
Compression seems good, better than last week so letting it rest for a week has loosened the rings?
Loose inlet manifold has been tightened up.
Worn insulation on the sparkplug lead was shorting onto the head (temp repair now done).
Exhaust was loose. It should be held by 2x 8mm bolts - and it clamps a heatproof shield to the head when in place. 1 bolt was snapped, 1 bolt was loose and part-stripped allowing the heatproof shield to slip down making a very effective blanking plate over the exhaust port
Looking through the exhaust port, the piston has several scores on it. Not ideal but I hope it's still ok to run.
It's obviously been apart since it last ran (carb inlet, exhaust, badly routed HT lead, bolts missing from the plastic motor shroud) but I don't know why. I guess because they couldn't get it started.

Latest :
With the exhaust off it fires every time, runs smooth but very flat, not at all crisp.
It won't start if the exhaust is fitted.
If I start it without the exhaust and fit the exhaust while it's running, it dies.
The exhaust has a small blanking plate welded on it, it's been done deliberately and looks DIY but I have no idea why? Repairing a hole, original but poorly finished??
I'm thinking the exhaust is partially blocked inside, I tried blowing through it and it seems to flow freely but I can't think why else the engine dies when the exhaust is fitted
Will remove the blanking plate and see if that helps.

Summary. Be skeptical of anyone selling tools you can't test if they say "You can't see it running but it works great, honest"