2 strokes

D

DaveHerns

New Member
I'm having a real struggle getting a Ryobi 2 stroke strimmer to run properly
What should the gap be between the flywheel and magneto pickups ? Is it crucial ?
I used a bit of cardboard to set the gap at 20thou but should it be smaller ?
Need to have a bit of clearance as it revs to 12000
 
Hay Dave , should of bought a Husquavarna ! Make sure the mixture is 50 to 1 , clean plug , clean air filter . Failing that sharpen the shears !
stina
 
Dave,
what are the symtoms? We've never had to mess around with magnetos (and our gear does get worked hard and frequently), but have found that the mixture needs regular adjustment on our saw, strimmer and hedge cutters (all Husquavarna). The spring on the mixture screws are far too weak. The strimmer is the worst offender as it has a large metal blade fitted full time and gets used alot, mostly keeping the electric fences clear of brambles.
Regards,
Dave
 
Does it have a fuel filter in the tank? My Stihl (far superior to any huskwossname!) started playing up after about 20 years without servicing. I bought a kit off eBay for a tenner, consisting of air filter, spark plug and fuel pickup filter and it's back to running like new. The air filter wasn't to blame as I'd tried running it without one and it made no difference. But the old fuel pickup filter looked filthy. It was on the end of a tube that hangs inside the tank - you hook it out through the filler cap with a bent wire.
 
Most of those small 2 strokes are sensitive to the type/brand of oil used as well as the mix ratio. Clean the plug and air filter and there should be a fuel one too, somewhere in the system, as mentioned.
Magneto gap shouldn't be too critical as it relies on induction and will need to be way out before it becomes problematic.

If it's been idle for a while, the mixture in the tank could have come out of suspension resulting in over oiling and fouling as a consequence. If it has a fuel cock, run it dry before storing it and drain the fuel into a container so you can give it a good shake next time before use. Fresh petrol probably won't hurt either if it stood a while.
 
I would just add that if the spark plug's old, don't bother to clean it, just buy a new one. The plug on my Stihl looked fine, but may have been the cause of the trouble. It was replacing either that or the fuel filter that cured it, but as I did them both at the same time I don't know which.
 
It's had a new plug , fuel lines ( when I cleaned the filter on the pickup pipe) air filter is clean .....
I've found out that a business card is the thickness to set the gap.
Sometimes it runs beautifully , other times it cuts out when hot and won't restart
I'll put it back together tomorrow and see what happens
I've seen reviews on the internet saying Ryobi and my model in particular is a piece of junk
I feel that if I can get 3500 cc's and 8 cylinders running , then 1 cylinder and 25cc's shouldn't defeat me
 
Hi Dave .
I don't doubt you know this all ready , but just in case . 2 strokes don't like the gentle touch , they tend to oil up the exhaust and plug if you don't rev them good and hard . Thrash it , opposite to the v8 !
stina
Ps , it's gone 5 o.clock , Friday evening , you shouldn't be trying to cut the grass now you should be having a beer !
 
No spark , no good
I think the magneto is faulty _ I've got a resistance reading between the HT lead and the magneto case but open circuit between the 2 terminal that go to the on/off switch - don't think that can be right
 
DaveHerns said:
No spark , no good
I think the magneto is faulty _ I've got a resistance reading between the HT lead and the magneto case but open circuit between the 2 terminal that go to the on/off switch - don't think that can be right
Click to expand...

I'm no expert, but on our old Husqvarna strimmer (or however it's spelt!), the switching-off action of the switch is to electrically join the the two wires together i.e when in the on position, the contacts are open, in the off position the contacts are closed and both wires are electrically joined to each other.

Addendum: According to http://www.ehow.com/info_7967049_gas-string-trimmer-wont-start.html,
Faulty Wiring
Two main ignition wires on your trimmer: the lead wire and the ground wire. The lead wire connects the ignition module to the spark plug. This wire can get ripped off the module or the connecting point may have gotten corroded. The boot on the tip of the lead wire can also get covered in dust, ripped loose and corrode. The ground wire runs from the module to the ignition switch. If this wire touches metal anywhere on the engine block before the switch, you'll be killing the circuit before it reaches the plug. Check all the connections to ensure this wire isn't corroded.
Click to expand...

That IMHO suggests the ignition switch on most, if not all, strimmers etc switches off by closing the contacts to electrically join the two wires.

Just a thought, has the insulation from the HT wire 'gone' weak and is in fact 'leaking' the HT pulse straight to ground/earth?
 
If my ground wire is open circuit to the frame of the magneto, shouldn't my strimmer run and not stop ?#
I could cope with that !
 
DaveHerns said:
If my ground wire is open circuit to the frame of the magneto, shouldn't my strimmer run and not stop ?#
I could cope with that !
Click to expand...

Yes, but I thought you said there was no electrical connection between the two wires that go to the switch.

I've got a resistance reading between the HT lead and the magneto case but open circuit between the 2 terminal that go to the on/off switch - don't think that can be right
Click to expand...

My point being is that does actually sounds right; if there were an electrical connection, it probably wouldn't even start, let alone run!

Have you checked there's no HT "leakage", BTW?
 
I think I'm explaining it badly - the "HT" side seems OK as there is a resistance reading between the plug cap and the coil body
But the terminals for the ground coil have an open circuit so it wouldn't (in theory ) make anny diference what position the swith was in

Don't think I've got HT leakage but HT lead is moulded into the coil so it's a new part irrespective
 
DaveHerns said:
I think I'm explaining it badly - the "HT" side seems OK as there is a resistance reading between the plug cap and the coil body
But the terminals for the ground coil have an open circuit so it wouldn't (in theory ) make anny diference what position the swith was in

Don't think I've got HT leakage but HT lead is moulded into the coil so it's a new part irrespective
Click to expand...

Then I stand corrected. :D
 
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