2 cycling with no spark at full throttle

[AVB]

Just wondering if any of the members ever seen a 2 cycle running at full throttle without spark as the limiter fully kick-in? Just repair a Stihl hedger that would and the dealer couldn't find anything wrong with it.

 

[Homemade]

Maybe it’s compression firing like a Diesel engine.....

Just kidding. I have no idea, never heard of that before.

 

[Lone Wolf]

Just wondering if any of the members ever seen a 2 cycle running at full throttle without spark as the limiter fully kick-in? Just repair a Stihl hedger that would and the dealer couldn't find anything wrong with it.

How can it run at full throttle with no spark? What makes you say there is no spark if its running?

 

[J_M____]

Is it a 4-mix engine? We had back pack blowers do that. It wouldn’t shut off. Ended up being a lot of carbon. The 4-mix are known to do that.

 

[Lone Wolf]

Does he mean run on when shut off?

 

[AVB]

Well here we go...

Is it a 4-mix engine? We had back pack blowers do that. It wouldn’t shut off. Ended up being a lot of carbon. The 4-mix are known to do that.

Nope regular 2 cycle. No it wasn't carbon.

Does he mean run on when shut off?

Nope.

Maybe it’s compression firing like a Diesel engine.....

Bingo. Dieseling at full throttle but not at partial or idle. It is accelerating above the coil's cutoff rpms.

So far Homemade is the closest.

 

[J_M____]

Was the timing off?

 

[Lone Wolf]

What rpm is it supposed to max at and what is it going up to? Is it definitively a limited coil? What machine is it?

 

[AVB]

Stihl HS56 8500 normal max with cut off @ 9300. This hedger is less than 6 months old.

It was passing the 9300 cutoff so far that the coil was completely shutting down hence unable to get max speed via inductive pickup. since there was firing of the plug. Sounded close to 120000. Yes my Tiny Tach is working fine as test against the Husqvarna 390xp with an unlimited coil hit 140000.

And the timing was fine.

Come on now. The dealer Stihl tech is already embarrassed when I told him what it was. He couldn't believe a self trained tech out did him with his factory training.

 

[Lone Wolf]

Stihl HS56 8500 normal max with cut off @ 9300. This hedger is less than 6 months old.

It was passing the 9300 cutoff so far that the coil was completely shutting down hence unable to get max speed via inductive pickup. since there was firing of the plug. Sounded close to 120000. Yes my Tiny Tach is working fine as test against the Husqvarna 390xp with an unlimited coil hit 140000.

And the timing was fine.

Come on now. The dealer Stihl tech is already embarrassed when I told him what it was. He couldn't believe a self trained tech out did him with his factory training.

If it has a limited coil and you cant get the idle down with the H adjustment then email Stihl and tell them to give you another coil. Or what else?

 

[Fish]

So the engine was running @ 12,000 or so?
With no spark?
Not sure I understand. Is the dealer just being standoffish because the warranty is voided?

 

[Fish]

I always have good luck when I go into a Stihl dealer and demand a new coil or two....

 

[Lone Wolf]

I always have good luck when I go into a Stihl dealer and demand a new coil or two....

Is that right?

 

[Fish]

I remember way back when, the distributor finally talked me into becoming a Kohler dealer, within a few weeks I had a gal coming into the shop with a reciept demanding a new muffler for an engine her husband had bought at some trade show.
I wasted way too much time on this silly gal....

So, I tend to side with dealers initially.

 

[Lone Wolf]

I remember way back when, the distributor finally talked me into becoming a Kohler dealer, within a few weeks I had a gal coming into the shop with a reciept demanding a new muffler for an engine her husband had bought at some trade show.
I wasted way too much time on this silly gal....

So, I tend to side with dealers initially.

A lot of dealers are not so great I only know one good one and I travel 1 hour to buy new saws and stuff. I cant stand the ones near me they act like they know everything and I don't know anything and are dishonest when you have a problem with a saw. Not a fan of liars!

 

[Fish]

A lot of dealers are not so great I only know one good one and I travel 1 hour to buy new saws and stuff. I cant stand the ones near me they act like they know everything and I don't know anything and are dishonest when you have a problem with a saw. Not a fan of liars!

Wow!

 

[Lone Wolf]

Wow!

Wow what its a true story which part is wow? You will find a lot of people feel the same as me! Working on a saw without authorization or not telling me then a bill is not what I call honest.

 

[AVB]

Okay guys. You're probably going to kick yourselves.

It was a bad spark plug. As Homemade guess it was dieseling at full throttle. When something diesels there is no need for a spark as the fuel becomes self igniting. In this case the spark plug was the hot spot.

Boy I getting to hate little 10mm plugs.

 

[Lone Wolf]

Okay guys. You're probably going to kick yourselves.

It was a bad spark plug. As Homemade guess it was dieseling at full throttle. When something diesels there is no need for a spark as the fuel becomes self igniting. In this case the spark plug was the hot spot.

Boy I getting to hate little 10mm plugs.

Hey at least you found it fast . Now put the plug back in and warm it up good then put some diesel in the tank and run it!