husqvarna k750 2-stroke - lent to a friend and now it wont run : (

[julianf]

Ive got a husqvarna disc cutter.

Symptoms are that it starts and runs fine... until any load is put on it. Then it stalls. Maybe not instantly, but i had to restart it about 8 times to cut one block, and it was getting worse and worse.

It will restart fine.

Im guessing its fuel or air (well, not a lot more it can be?)


Background -

machine bought used
always started and run fine, but...
if the fuel has been left in it, i have to change it, before it will start. suspect it has a tiny leak somewhere and the volitiles evaporate (fuel i tip out always looks too red)


Ive not even bothered to ask the person i lent it to, as im sure they will say it was running fine...

 

[rikrobson]

does it have the correct oil/ratio in the petrol? Two stroke oil is usually green

 

[julianf]

all that ive ever used (i have not used much, but its not my first unit) has been red, and the mix (and oil) is the same as i have been using

 

[julianf]

ps. this isnt what ive got in it, but ive used these before -

theyre red too.

 

[rikrobson]

I've got green stuff, i suspect that there may be a lot of different colours

 

[Paul99]

Clogged air filter? - ours goes like that when it gets a bit dusty - after that I'd take the carburettor apart and clean it out with brake cleaner sometimes the jets, air/fuel ways etc get a bit gummed up with 2 stroke oil.

 

[Fintray]

Just a thought but are you sure the person you lent it to was using two stroke and if so at the right mix?

 

[Migmac]

Check the clutch, mixing oil comes in lots of colours.

 

[Digger6135]

Go round and brick his windows :-))

 

[Wendelspanswick]

My vote is try a new plug, see recent post on subject.
http://www.mig-welding.co.uk/forum/threads/honda-gx35-brush-cutter-wont-run.53769/#post-629724

 

[pedrobedro]

Take the silencer off and check the piston for scoring you might be low on compression when it gets warm. Mix oil comes in many colours, Stihl is red, Husqvarna is blue and I have some green from Comma. It could be the carb diaphragm has a pinhole or has hardened if it's been left with fuel in or the metering needle is sticking. I put a new Walbro carb kit in one of my chainsaws a couple of weeks ago only cost about £4 from ebay.

 

[wristpin]

Whip the exhaust muffler off and have a look at the piston and see if there are any signs of seizure or stuck rings. If there are it has suffered a partial seizure.
Hopefully no sign of seizure so check that the muffler is not choked. Some machines have a spark arrester (a piece of steel mesh ) in the exhaust outlet and they clog. Unless you are working in an area where spark arresters are required, pull it out and sling it. If it's a steel muffler you can cook it with a blow torch to burn out any oil and carbon.
Two stroke mixing oil is coloured just as a tell tale, the colour is irrelevant to the lubricicity.

On edit
Sorry, the last post appeared while I was writing this but the advice is good!

 

[julianf]

I took a look at the air filter, and that looks pretty grubby, so ill order one of them.

I cant think that its piston damage, as it was running fine, and i know he only used it to chop up some metal gates somwhere where there was no power - i cant think that he would have managed to knacker the bores etc that quickly.

My feeling (from running cars with blocking fuel filters) is that its a fuel issue, but, all that aside, i asked for advice, and i always think its foolish to ask if youre not going to pay attention, so i will make the checks above.

 

[wristpin]

Call me a cynic but after 30+ years in the business the majority of seized machines that we saw "had been lent to a friend/ neighbour" allegedly !!!
Going along with your fuel filter theme , don't forget the one on the end of the "wobble tube" in the fuel tank.
Hopefully your machine has not suffered a catastrophic failure so when you get it sorted it's worth considering the use of a fuel stabiliser that not only extends the time before the fuel degrades/goes stale, but also combats the ethanol related issues that are becoming more of an issue now that all pump fuel contains at least 7% ethanol with the prospect of the percentage being raised to 11 and 13 in due course.

 

[robinj66]

As above check the air filter - if you haven't got a replacement to hand you can blow them through easily.
Also as above change the plug
There is a filter inside the fuel tank - hook out the hose and take a look - its a push on filter which can get blocked and restrict flow.

If that doesn't sort it they are pretty easy to strip down - mostly a torx and a 13 mm socket. the carbs are simple to get to but small and fiddly to inspect.

If nothing else works then follow the advice and check the piston/bore - they can still run with broken rings etc

 

[CRB]

If I have missed it above, apologies.

Venting to the tank. Just enough air getting in at tickover, but not enough to allow the motor to rev.

 

[julianf]

If I have missed it above, apologies.

Venting to the tank. Just enough air getting in at tickover, but not enough to allow the motor to rev.

I tried that one - loosened the cap, but did not make a difference.

 

[julianf]

I'm going to have to RTFM on this one - whilst getting to the air filter is simple enough, its not immediately obvious what I should attack to get to the rest of it.

 

[CRB]

I'm going to have to RTFM on this one - whilst getting to the air filter is simple enough, its not immediately obvious what I should attack to get to the rest of it.

Come on Julia, I expected more from you.

 

[julianf]

I'm not the best with unknown engines.

In fact, I'm not that great at most things.