Stihl MS460 wont start

[173abn]

I've got an MS250 that I just put a new flywheel on due to the perment key breaking.Have you checked that ?I then had a hole in the fuel line and had to tear the whole thing apart just to replace that $14.00 line.Any more problems and I might have to try a diff. brand of saw...russ

 

[bwestbrook]

I have not checked the flywheel key. I thought about that while I was typing that last post.

Wouldn't have this problem if it was a Husqvarna!! Haha

 

[Rivets]

Have tried to close the gap on the coil? .008 instead of .010.

 

[bwestbrook]

I have always just used a business card. I will check that too. I am at the fire station today so it will be tomorrow before I can check.

 

[Rivets]

I know that the vast majority of people use a business card, but I have found that they are unreliable. One year I had my students each bring in 10 cards and mic them. Card sizes ranged from .006-.013. Only 40% actual measured .010. The most accurate substitute for a feeler gage that I have found is a microfiche card folded in half.

 

[bwestbrook]

I tried a good coil and adjusted the gap to .010 and also .008. Still nothing.
I also checked the key and everything is in place as it should be.

 

[DaveTN]

I used a regular spark tester from a parts store. I had the gap between .30-.40. It was a food blue spark. I also check the plug by grounding it to the cylinder. Same result. I have not made it by the Stihl shop yet.
If it was not producing a good spark under compression would it not produce a good spark with the decompression valve pressed. I don't have much experience with the decompression valves.
This saw was purchased from a pawn shop and has not run since purchased. So I don't know any history on it. It just has me going nuts. Haha!!

Just wondering if you did a compression test on it? Even if it was in the fault of the decompression unit, still you'd have to get enough compression to run. With good blue spark and compression it should run! Seems plenty of gas is not the issue here. I just use a tiny amount of 2 cycle gas mix, say 1/4 teaspoon down in the spark plug hole and pull it over. It should at least give a quick start and run till the gas is burnt out. I hate a temperamental unit! Good Luck

 

[bwestbrook]

I got 90 psi on compression test.

 

[taxidermist]

There is your problem. Remove the muffler and look at the piston it will be scored from a lean mixture. I have rebuilt a bunch because they try to start them with old gas with E-10 in it and the fuel has seperated(phase seperation) I use the aftermarket pistons and cylinders from here

Bailey's - NWP Cylinder Assembly for Stihl 046, MS 460 Chainsaws

If you look around you can find a 54MM big bore kit which is what i use.

Rob
Ann Arbor Firefighter, Michigan
local 693

 

[MrWobbly]

Gentlemen: This is a great forum. This afternoon, my MS460 refused to start although it was running okay last week when I shut it down. After many crankings, I tried some ether. When that did not fire, I put a screwdriver into the spark plug boot and pulled the rope vigorously, several times, with no detected electrical charge. From what you all have written, my coil must be bad. Or, is there something else to look at? Can the throttle/choke switch get out of sync somehow?. As an amateur, should I try replacing the coil myself?