Any two-stoke experts able to give help.

[Ricard with an H]

I bet i'll be Our-Sally.

I'm Ok with all the most sensible things like draining the fuel before the winter lay-up, never using old fuel, clean the air filter, always use a quality two stroke oil and change the plug because it's cheap. other than that what on earth is the reason two strokes decide to misbehave.

I've proven the plug is fine by using one out of a machine that works, I know fuel is getting into the combustion chamber because the plug is always wet. It's wet because it hasn't started, yes ?

Two days ago my smallest brush-cutter reluctantly started and worked for about half a tank of fuel-mix then just died on me and never started again, similar with the hedge cutter but it did eventually start.

All my machines are within five years, I have a heavy brush-cutter, a lighter weight version, a hedge cutter. All these are Kawasaki, then I have a Husqvarna chain-saw and a Stihl blower. Only the Stihl blower has never given me a problem, it gets the same treatment and the same fuel.

Any ideas ?

[Geoff]

I'm no expert but multiple simultaneous problems suggest to me the common factor of fuel. I long ago gave up mixing bottles except that I use two that I have to measure ½ or 1 litre then a measuring cylinder for 20 ml of oil to give me 25:1 for the chainsaw and 50:1 for the strimmer. You have used the suggested ratio for each machine I suppose?

[sally wright]

Dear Richard,
I would agree that it sounds like a fuel problem. I might guess that you have probably double dosed on the oil by mistake or used the wrong kind of oil. If you take the plug out after the stoppage is it very black?

I would look at mixing up a completely fresh batch of 2 stroke mix using new petrol and a fresh pot of oil as well and double check your sums to make sure that the ratio is as specified in the manuals. After all there is no reason why several machines should pack up at once other than fuel. It is not wasteful to discard the duff batch because it is probably over £1000 worth of engines at risk here.
Regards Sally Wright.

[Ricard with an H]

Ahh-thanks, I proved the fuel-mix because all the other machines are working with that same mix.

I have a spark but I suspect the ignition coil for some reason I can't explain so I stripped the whole machine down. The ignition coil contacts on any machine can get interrupted with muck and dust, more particularly a chain-saw I suppose.

It's all stripped down now but I don't yet know what i'm looking at. Some carbon build-up on the cylinder head and piston. I have some test points and resistance tests for the coil but i'm far to tired now so it's a tomorrow job. It's the first time I ever stripped a two-stroke engine, first thing I noticed was how dry everything is compared to a four stroke. No oil residue anywhere.

Maybe i'll be an expert by the weekend, Eh ?

[Clive.]

Worth a check on 2 strokes is the exhaust outlet. A blocked exhaust silencer can give some interesting effects. Blocked, they can often ingest fuel mix but can't expel exhaust.....and go lethargic and stifled. Many small modern machines have a spark arrester screen at the exhaust outlet and this thin gauze can soon block up especially if running too rich, heavy on oil or using a low spec' oil at an increased oil ratio.

Fuel pick up filters in tanks can fill with sediment and cause poor fuel pick up, weak running.

There can be "rubber" non return type vents in the fuel cap that can perish and stick.

My limited experience of current electronic ignitions is that they often work or they don't...as in alive or dead. I did once have a problem on an early electronic ignition large Stihl chainsaw that had a break to be jumped at the plug cap and that caused a timing type spark error that pulled the rope out your hand with some force...

A new plug is always worth fitting....I have been caught out by seemingly fine behaving other plugs although a failed plug can be symptomatic of a deeper real problem.

Once full of fuel mix in the crankcase they can remain "flooded".

Be very careful of any spark testing with spark plug laid on cylinder like might be done on a 4 stroke....as with a plug sparking near the plug hole as the engine is test spun and a crankcase full of mix you can get a mist of fuel that ignites with a fair whoosh.....


Hope all goes well with the learning experience.

Clive.

[robo]

2 strokes can suffer with leaking crankcase seals which means no pressure in the crank case, also leaking gaskets on carbs will cause running problems, once its all back together if it still wont start take out the plug put it over a gas flame and get it hot put it back in as quickly as possible if there is no other problems that will usually start it

[Ricard with an H]

Thanks for the helpful comments and you've a few things for me to check, it seems taking the machine apart isn't such a bad idea if only to clear the carbon build.

I hadn't even thought about an exhaust muffler being a problem and what scares me even more is after two days of intermittent searching I cannot find a comprehensive supply of spares for the engine even though the Kawasaki machines have been regarded as the best for power/weight ration and quality of build.

My local supplier who was a Kawasaki dealer and prior to that dealt with (I can't remember) is now a Stihl dealer, every two-ish years they change dealerships and the cynic in me says there is a dodgy reason.

The reason I thought about the ignition coil contacts was because new machines always start easily then slowly deteriorate, I just couldn't think of anything else in a two-stroke engine that would stop the machine if fuel-mix is getting through to the combustion chamber and i'm aware that the presence of a spark by taking it out and earthing it doesn't necessarily mean it's working correctly ? (That was meant to be a question)

[Ricard with an H]

Everything is working again but it took two hours to start. I haven't a clue why it stopped nor do I know why it wouldn't start. Certainly the coil is fine so it can only be the carb.

I just ran it for an hour, now i'll it go cold and try to re-start it. Is this another one of those black-arts ?

[Clive.]

I hope all goes well from cold start...

I needed some parts for a Kawasaki 4 stroke engine on a John Deere Lawn edger a few years back and had very good mail order service from a firm in Corby, Northants.
I couldn't recall the name but I think it could well have been... http://www.corbykawasaki.co.uk/ Garden machinery comes under Power Products.

Clive.

[Ricard with an H]

Thanks for that Clive, and i'll have something more to share with you-all shortly but I need time to consider and the three Kawasaki machines need to start up again in the morning to prove a point.

Not a Ureka-moment but maybe something to seriously consider, how many of us replace the fuel-filter regularly ? I have never replaced a fuel filter and todays phone-around my friends and others suggests no-one ever changes the fuel filter until things get desperate.

[Ricard with an H]

OK, it's slashing down with rain so i'm not going to treble-test my theory.

All three Kawasaki machines and a Husky chainsaw present starting problems from cold of some sort, the older the machine the worse it is. The one machine I have no trouble with is a recent purchase Stihl blower.

I think the fuel filters are the big problem, most manufacturers recommend replacement every year, non of mine have ever been replaced after 11 years, six years, 5 years, 3 years and two years. Thats the ages of each machine I have.

How I finally got my machines to start in all of three cases yesterday was to drain the tank then pump the fuel out of the carb by using the bulb which returns the fuel to the tank, after doing that each machine fired immediately but quickly ran out of fuel, by adding fuel after this odd way of starting the machine worked for over an hour, was let to go cold but easily started again and again a third time.

I know it isn't helpful to guess but I always have used the laws of probability, if it quacks it's likely to be a duck.

How many of you people ever change your fuel filter ? My neighbour hasn't changed his in four years and doesn't have starting problems but does that blow my theory out of the water ?

Later in the season i'll be able to add more solid evidence but please do contribute your ideas.

[Ricard with an H]

Well, this afternoon they all-three started easily from cold and I don't have a clue why they didn't or why they do-now. I found no-faults, the fuel was fresh and hadn't been double-dosed (yes-I did that once)

The 23 cc brush-cutter was stripped and de-coked a couple of days ago and today I stripped the 48 cc. Wow, that was really coked up but it is eight years old. I noticed the crank-case, piston and cylinder were all liberally coated with the red oil I use but when I stripped the 23 cc it was almost dry inside.

The coil-contacts were clean though rusted on the coil itself and I did have to remove a lot of chaff from around the cylinder fins and in-between the carb and muffler.

No signs of problems and I have ordered replacement fuel-filters on the basis of handbook recommendations.

[sally wright]

Dear Richard,
I have just re-read your initial post because I had the feeling I had missed something when I read your post the first time and I was right. Two stroke engines should not be drained before winter storage. The reasons being that an empty tank allows the diaphragms and seals to dry out and also because the oil residues break down and sticky up the inner workings of your machine. Ideally they should be left with full tanks.
To avoid wasting the fuel mix when spring comes round, tip it into a specially marked can and add a little to future fuel mixes during the season until it is used up. Although do use completely fresh fuel mix for the initial spring start up.
Regards Sally Wright.
ps. I don't think i have ever had to replace a fuel filter, we usually just soak them in petrol and scrub with a small tooth brush.

[Ricard with an H]

Oh-wow, thanks for that Sally.

Sounds to me like the carb and fuel-filter could both be effected by the oil/fuel drying, I don't know where I got the idea of draining fuel for winter storage though I most-definately did many years ago and the Kawasaki handbooks all recommend draining the fuel and running the machine dry for storage periods of 30 days or more. The Stihl handbook says the same and talks about a cleaning fluid but doesn't go into detail.

The Kawsaki handbook also recommends filling the cylinder through the plug hole with two stroke oil.

I'm now wondering if the handbook advise is something that has been written in stone and never considered against the facts gained by users of many machines over many years so can you clarify that your method has been a success whilst also being aware of manufacturers storage instructions ?

[Ricard with an H]

I've just done a quicky research on the internet. Seems that using fuel stabiliser in your fuel then leaving that in your machine is a good way to go.

Still plenty of experts recommending a total drain-down though, i'm going with the fuel preserver this season and the case for replacing the fuel filter is reiterated though my neighbour has machines of twenty plus years old that have never had any of this treatment and even have the original plugs.

Fried or boiled ? Anyone ?