OLD husqvarna rancher 50 not starting - seems to have spark, compression, fuel, timing?

[Vintage Engine Repairs]

Go back to basics, forget about timing unless you or someone has removed the flywheel and destroyed the key....unlikely but I have seen it when people play with saws and think because they can change an air filter on their truck they can easily work on a saw. Timing never just goes out unless the flywheel is loose. A lot is mentioned about fuel down the plug hole or squirted into the carb, again you can get away with this on a car but a saw needs a very small amount and this has to be cleared before more is added or you end up with too much fuel in the crank and it will never start.
So go back to basics and start with a vac test, check fuel filter or replace and pressure test fuel pipe, that's the first thing along with fuel quality. You may have put new in but what was in it before. A vac test maybe out of your scope but is a necessary test and easy to do, it's a simple two stroke engine but if everything checks out and it still wont run, check again. Set carb to standard settings, If it gets too much sleep on it and often something will come to you and bingo it runs.
And lastly, I know men who cant start their saws, nothing wrong with both saws I can start them easy. So why
They cant pull them over fast enough. One is 35cc the other 60cc
They both blamed the saw until it was pointed out to them.
Good luck I hope you can solve it.

Yes it certanily can - most modern ignition coils have an ignition curve. The microprocessor that controls this calculates engine speed off the flywheel rotation against a quartz clock. This gives the micro processor the information to calculate engine rpm. With this information, it sends a signal to a transistor which then releases the current in the primary windings into the secondary to create voltage / spark at the pre determined time. If the microprocessor doesn’t close the transistor you get rev limitation. Therefore it goes without saying, when these components fail, the spark can be anywhere.

 

[dboyd351]

So would that be the case with Husky 50?
I think that saw is nearly 40 years old.

 

[Vintage Engine Repairs]

unless it’s running points even without variable timing, a faulty electronic ignition module can cause spark timing to be way off. Don’t overlook it.

 

[Husky77]

Yes it certanily can - most modern ignition coils have an ignition curve. The microprocessor that controls this calculates engine speed off the flywheel rotation against a quartz clock. This gives the micro processor the information to calculate engine rpm. With this information, it sends a signal to a transistor which then releases the current in the primary windings into the secondary to create voltage / spark at the pre determined time. If the microprocessor doesn’t close the transistor you get rev limitation. Therefore it goes without saying, when these components fail, the spark can be anywhere.

Good point
But surely that's on the newer rev limiter coils. It does make sense but I would tend to rule it out on this saw.

 

[Vintage Engine Repairs]

Good point
But surely that's on the newer rev limiter coils. It does make sense but I would tend to rule it out on this saw.

Na any electronic ignition, rev limited or not, ignition advance curves or not

 

[Old2stroke]

Yes it certanily can - most modern ignition coils have an ignition curve. The microprocessor that controls this calculates engine speed off the flywheel rotation against a quartz clock. This gives the micro processor the information to calculate engine rpm. With this information, it sends a signal to a transistor which then releases the current in the primary windings into the secondary to create voltage / spark at the pre determined time. If the microprocessor doesn’t close the transistor you get rev limitation. Therefore it goes without saying, when these components fail, the spark can be anywhere.

Is it just one particular manufacturer that is using a microprocessor? Sounds like overkill, chainsaws don't need an elaborate timing curve and a regular electronic coil does a decent job of meeting the requirements with just simple semiconductors. Be nice if they would just start using Mil spec components and improve the reliability of the units.

 

[Vintage Engine Repairs]

Is it just one particular manufacturer that is using a microprocessor? Sounds like overkill, chainsaws don't need an elaborate timing curve and a regular electronic coil does a decent job of meeting the requirements with just simple semiconductors. Be nice if they would just start using Mil spec components and improve the reliability of the units.

Yeah most if not all modern 2 stroke small engines use variable spark timing through microprocessors. I was surprised to find a 15+ year old plastic homelite hedge trimmer had variable timing! It was sparking at about 8 degrees BTDC at a few hundred rpm.

 

[stihltech]

Wow, cart before the horse.
Basics first. That is what repairs 99 per cent of the saws in a shop.
The only saw I ever had an actual timing issue was a MS 361. But that is it.
And when frustrated, walk away, sit a spell,have the beverage of choice and resume later verifying from the beginning. Something will show. Don't slap you forehead too hard when it does.

 

[ZeroJunk]

So would that be the case with Husky 50?
I think that saw is nearly 40 years old.

Think this thread is a year old..

 

[Bob Hedgecutter]

Think this thread is a year old..

OP is possibly still trying to work through and get his head around the over complication of simplistic matters in regard to some of the replies?

 

[dboyd351]

Think this thread is a year old..

Well then now he has a problem with the gas being stale, especially if it has ethanol in it.