Stihl HS45

[Bob970]

Will not try to start, not even a pop. Good spark. Good compression. put gas in spark plug opening. Still won't even pop
Any help would be greatly appreciated

 

[alexcagle]

Check your flywheel key that it's not sheared. Pull the plug, put a screwdriver on the piston top. After you find tdc, look at the magnet on the flywheel and see that it just leading the coil. If not then it's probably sheared.

 

[Bob970]

We put a new flywheel on. did notice a little play in both directions. I'll check at tdc and see where the magnets are. Thanks for your input

Bob

 

[alexcagle]

When you put a flywheel on, it's important that the crankshaft hub taper and the flywheel hole be oil free. Use brake cleaner, laquer thinner, or acetone on a paper towel. When you tighten the nut, put some clean starter rope in the spark plug hole when the piston is about 1/2 way up. Leave the end of the rope hanging out; of course, for retrieval. Or ; if you are careful, you can use a screwdriver to keep the crankshaft from spinning as you tighten the nut by sticking the screwdriver between the coil and the flywheel magnet. Don't use a weak place, and break a fin off. Use a strong part of the flywheel. You need to get it gutentight too.

 

[ANewSawyer]

What's gutentight mean?

 

[arrow13]

What's gutentight mean?

That's "good and tight" in Norveegian

 

[ANewSawyer]

But Alex isn't from norvegan.

Sorry to the op. I would replace the spark plug, or even swap for a known good one. It seems like someone on here metioned plugs not sparking under compression.

 

[Bob970]

Did that too. Thanks for the reply. All suggestions greatly appreciated

 

[ANewSawyer]

My mechanical ability is small, I just leach off other peoples knowledge. Still, it should be running. @HarleyT @backhoelover

Obvious question, how old is your gas? Ethanol or 100% gas?

 

[Bob970]

Fresh gas. 89 octane 2days old

 

[CR888]

Kill switch faulty?

 

[Bob970]

Disconnected it. This one is a tough one. I put tester on spark plug . Great spark. put some clean gas in spark plug hole. Will not pop. Compression is 140. No air leaks detected with block offs in place.

 

[arrow13]

How's your plug wire condition? Check for solid connections on both ends. I've had the prong set on the side of the wire core and not work well enough until I re-positioned it in the center. Got a better spark.
I also would check the wire for any cracks. I've had a saw start and run fine one day and not the next. It was shorting out through a hidden crack that was covered by a chafing shield where the wire went through the casing.

 

[Bob970]

I'll check that out today. Thanks.

I recently had an Echo trimmer with that exact situation

 

[backhoelover]

When the plug is not in cylinder and not under compression it take a 1000 volts to fire plug. When the plug is in cylinder under compression it takes 10,000 volts crazy huh???

 

[backhoelover]

What plug so you have in it

 

[Bob970]

What plug so you have in it

BPMR7A

I took old flywheel and ground the key out. Then I compared flywheel magnets to coil on a Stihl blower. Set the flywheel the same on the HS45 and Voila , it runs fine. Got me. but it runs

 

[backhoelover]

Glad you got it

 

[WoodTick007]

What's gutentight mean?

Seriously?

 

[ANewSawyer]

Yes, it was a joke.

Op, glad you got it running!