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Homelite 450 won't start.

Evil XL 12

Evil XL 12

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Apr 4, 2021
Messages
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Location
Tennessee
Hi everyone. I've been following this site for a long time but just recently became a member. I hope I'm posting this in the right place. I'm not a professional when it comes to chainsaws but I can see that there are some very knowledgeable folks here and I hope you can help. I've always been fascinated by chainsaws and started buying and fixing them almost a year ago. It's surprisingly addictive and I've been able to fix a couple dozen of them so far. I have a homelite 450 that has been stumping me for a long time. It won't start. I've replaced the spark plug, the fuel lines and filter, the impulse line, and the start switch. I've transplanted the coil and transformer from a running saw to it. I can touch the contacts that the transformer goes across and when I pull the cord it shocks me real good. I rebuilt the carburetor. I also checked the rubber carburetor boot for holes/cracks. The cylinder and piston aren't scored from what I can see and it has 155 psi compression. It acts like it has no spark. It doesn't even pop when I pour fuel directly into the carburetor. I don't know what else to check. Sorry for the bible length post but I want to present a complete picture of what I've done so far. What have I overlooked? At this point the only thing I can think of is getting a priest to perform an exorcism on it.
 
MacAttack

MacAttack

I love the smell of 2-stroke
Joined
Nov 15, 2019
Messages
1,265
Location
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Hi there, you're screenname makes me wonder if you're a fellow Evil Dead fan haha.
Are you able to see a spark at the spark plug? I would put the plug wire on the plug with the plug out of the cylinder, but with the plug body touching something to ground it (any metal part of the saw), or make up a lead wire with an alligator clip on each end to ground it. Pull the saw over quickly in a dark room to confirm spark. If yes then 2 possibilities in my mind, SEVERELY flooded, or, flywheel key sheared, flywheel is spun on the crank and spark timing is off. Otherwise, it should run with compression and fuel poured into the cylinder.
 
Evil XL 12

Evil XL 12

ArboristSite Lurker
Joined
Apr 4, 2021
Messages
11
Location
Tennessee
Hi there, you're screenname makes me wonder if you're a fellow Evil Dead fan haha.
Are you able to see a spark at the spark plug? I would put the plug wire on the plug with the plug out of the cylinder, but with the plug body touching something to ground it (any metal part of the saw), or make up a lead wire with an alligator clip on each end to ground it. Pull the saw over quickly in a dark room to confirm spark. If yes then 2 possibilities in my mind, SEVERELY flooded, or, flywheel key sheared, flywheel is spun on the crank and spark timing is off. Otherwise, it should run with compression and fuel poured into the cylinder.
Thanks for the advice. I am an evil dead fan and it is a reference. I've checked the key and it's okay. The saw has a transformer that goes over the spark plug instead of a plug wire. It's not great because it makes it impossible to check for spark with that method. I will check for flooding. There is no fuel coming out of the exhaust but. I can't remember if the plug was wet or not. I'll go out and check
 
Evil XL 12

Evil XL 12

ArboristSite Lurker
Joined
Apr 4, 2021
Messages
11
Location
Tennessee
Is there anyone else who has any ideas? I'm wondering if I'm posting questions in the wrong place. I've only started 2 threads and only one person responded in each instance. Am I posting in the wrong place?
 
MacAttack

MacAttack

I love the smell of 2-stroke
Joined
Nov 15, 2019
Messages
1,265
Location
USA
Can you share a pic of whatever attaches to the spark plug? You should be able to use some ingenuity to check for a spark at the sparkplug with the saw assembled.
To check if it's severely flooded, hold the saw with the spark plug removed and the plug hole pointed down, pull it over quickly and see if gas spatters out. If so, pull it over until gas stops coming out the plug hole.
 
GoBigRed

GoBigRed

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Joined
Jul 3, 2021
Messages
90
Location
western washington
Those transformers are known to fail and if you replaced the intake boot and correctly rebuilt the carb, there is a good chance that it has failed. You can test resistance to see if it is working correctly. There is also a spring that connects to the plug and that can break or crack.
It’s kinda crappy, but folks know those transformers can bring a premium if you can find them. So a lot of times, usually with the 360s, they get passed off as just needing a carb rebuild. Then you find out it has the spark issue.
Test the transformer and make sure it isn’t open. I don’t know what the exact resistance should be but it shouldn’t be open on the windings.
 
Evil XL 12

Evil XL 12

ArboristSite Lurker
Joined
Apr 4, 2021
Messages
11
Location
Tennessee
Those transformers are known to fail and if you replaced the intake boot and correctly rebuilt the carb, there is a good chance that it has failed. You can test resistance to see if it is working correctly. There is also a spring that connects to the plug and that can break or crack.
It’s kinda crappy, but folks k
Those transformers are known to fail and if you replaced the intake boot and correctly rebuilt the carb, there is a good chance that it has failed. You can test resistance to see if it is working correctly. There is also a spring that connects to the plug and that can break or crack.
It’s kinda crappy, but folks know those transformers can bring a premium if you can find them. So a lot of times, usually with the 360s, they get passed off as just needing a carb rebuild. Then you find out it has the spark issue.
Test the transformer and make sure it isn’t open. I don’t know what the exact resistance should be but it shouldn’t be open on the windi
now those transformers can bring a premium if you can find them. So a lot of times, usually with the 360s, they get passed off as just needing a carb rebuild. Then you find out it has the spark issue.
Test the transformer and make sure it isn’t open. I don’t know what the exact resistance should be but it shouldn’t be open on the windings.

Those transformers are known to fail and if you replaced the intake boot and correctly rebuilt the carb, there is a good chance that it has failed. You can test resistance to see if it is working correctly. There is also a spring that connects to the plug and that can break or crack.
It’s kinda crappy, but folks know those transformers can bring a premium if you can find them. So a lot of times, usually with the 360s, they get passed off as just needing a carb rebuild. Then you find out it has the spark issue.
Test the transformer and make sure it isn’t open. I don’t know what the exact resistance should be but it shouldn’t be open on the windings.
I will
Those transformers are known to fail and if you replaced the intake boot and correctly rebuilt the carb, there is a good chance that it has failed. You can test resistance to see if it is working correctly. There is also a spring that connects to the plug and that can break or crack.
It’s kinda crappy, but folks know those transformers can bring a premium if you can find them. So a lot of times, usually with the 360s, they get passed off as just needing a carb rebuild. Then you find out it has the spark issue.
Test the transformer and make sure it isn’t open. I don’t know what the exact resistance should be but it shouldn’t be open on the windings.
I will post a picture of it. I actually have a couple of running 360s and I've put known good coils and transformers from those saws onto the 450. I will still test for resistance though. I'm going to look into possible flooding as well. I had issues with that on a 360 that I fixed. I rebuilt the carb with a foreign kit and the little metal nipple on the diaphragm is too tall, which caused it to flood. It was bad enough that fuel was spraying out of the muffler. I put an OEM Walbro kit in it and it fixed the problem. I used an OEM kit for the 450. Thanks for the good advice guys. I'll post a picture and let you know what happens.
 
GoBigRed

GoBigRed

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Joined
Jul 3, 2021
Messages
90
Location
western washington
I went back and reread your original post. I had something similar with a 10-10a that was giving me fits. I swapped carbs from a good saw and after nearly a year of jacking around with it, she finally ran. Although the other carb was cleaned in an ultrasonic cleaner, I decided to pop off the Welch plugs and then soaked it again. I replaced the plugs, put it back on the saw, and she fired and ran like new.
What is your low setting on the carb it currently has? Did you pour in fuel or did you put a shot of ether in it?
 
Evil XL 12

Evil XL 12

ArboristSite Lurker
Joined
Apr 4, 2021
Messages
11
Location
Tennessee
I went back and reread your original post. I had something similar with a 10-10a that was giving me fits. I swapped carbs from a good saw and after nearly a year of jacking around with it, she finally ran. Although the other carb was cleaned in an ultrasonic cleaner, I decided to pop off the Welch plugs and then soaked it again. I replaced the plugs, put it back on the saw, and she fired and ran like new.
What is your low setting on the carb it currently has? Did you pour in fuel or did you put a shot of ether in it?
D
 
Evil XL 12

Evil XL 12

ArboristSite Lurker
Joined
Apr 4, 2021
Messages
11
Location
Tennessee
Sorry, I just saw this. The low setting is 1 1/4 out. I tried fuel mix and ether. It hasn't even popped like it was trying to fire. I will go through the carburetor again though. I really appreciate your advice. I guess if nothing else, I have a parts donor for my 550. I'd love to cut something with both of them though.
 
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