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McCulloch 10 10 diagnostic help needed

Willoughby

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I bought a McCulloch 10 10 , seller said it runs good but after draining fuel and oil to ship it ,when I get it, I filled it with fuel and oil and pull on it for a while and it wont start , it has spark and the choke works , tried a new plug , checked compression it has 90 psi compression , Im a retired auto tech and I know 4 stroke engines will start and run on as little as 80 psi , they wont run good but they will start , and they also have multiple cylinders, I do have a basic understanding of 2 stroke single cylinder engine operation but I'm still pretty green yet, how much compression is needed for a saw to start and run ? thanks in advance for any responses
 

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That sounds low enough to indicate some sort of problem.
Also with could of this vintage some will produce spark but not strong enough to fire. Should be able to jump a 5mm air gap to test.
I would slide the muffler out and look at the piston through the exhaust port as my next move.
 

Willoughby

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Ill see how much spark its capable of making and pull the muffler for a look at cyl & piston , and then get back with findings early next week . thanks a lot for the help
 

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Here anything two cycle that has less than 100 psi seldom starts although I had one Poulan that was @ 95 pis that started but ran terrible. I tend use 110 psi as a good minimum compression reading when checking out two cycles.

Just note not compression tester are meant for testing for small engine and their Schrader valve are not as responsive ( too much spring tension) as they should be which leads to false low readings. And throttle should be held wide out for compression testing too.
 

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Have you tried a small shot of carb cleaner in the carb and then try to start it?
 

Willoughby

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ok here's a update I cleaned fly wheel and coil a bit pulled muffler and found both piston and wall scored , put back together , still wont start, Im thinking low compression is the reason ?
 

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ok here's a update I cleaned fly wheel and coil a bit pulled muffler and found both piston and wall scored , put back together , still wont start, Im thinking low compression is the reason ?

Will have to be rebuilt before it can be ran again.
 

Willoughby

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also tested on off switch , I can get 6 =7 mm spark , 90 psi max with throttle open its toast because there's no parts available for it
 

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also tested on off switch , I can get 6 =7 mm spark , 90 psi max with throttle open its toast because there's no parts available for it
Did you set the points gap and clean them up?
Can you post pictures of the scoring?
 

rwillower

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I was the seller of this good running mac 10-10. I don’t and would never sell a non running saw as a running saw. Saw ALWAYS started in 5-6 pulls, idled and revved to the moon. Here’s 1 of a couple videos I have of it running to prove it. I have a very good reputation with the guys over at the Husqvarna page on Facebook and I sell a lot of saws. First time I’ve ever had an issue. I’m glad I video my saws I’m selling. Also after cutting him a deal with shipping, the shipping estimator was way off and was another $33 more to ship it which I didn’t even ask for another dollar from him I didn’t even ask for another dollar from him since I made a deal with the guy I made a deal with him for $130 shipped to him. I know that saw was when it left my hands
Here’s the link to prove it
 

rwillower

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Also I see he has another thread with another 10-10 with good piston/cylinder but low compression
 

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Maybe something happened during shipping. Seems unlikely it would run good like that then the seller cant get it to run. If the piston/cylinder is scored then pics are in order. Maybe its not scoring but just some carbon streaking.
 

Marshy

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@Willoughby, what kind of compression tester are you using. The hose needs to have a Schrader valve in it and the hose needs to thread into the spark plug hole. You cant use an auto type compression checker with the rubber tip that you hold into the spark plug hole...
 

rwillower

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@Willoughby, what kind of compression tester are you using. The hose needs to have a Schrader valve in it and the hose needs to thread into the spark plug hole. You cant use an auto type compression checker with the rubber tip that you hold into the spark plug hole...
All I do know is I sold him a perfectly good running saw when it left here. I honestly have no clue what’s going on but that’s not the type of person I am. There’s a few on here that’ll vouch for me I’ve even tried to help and he has my actual phone number as well. I wouldn’t do this to someone ever. I have proof it was a good runner and that’s final
 

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I find a bit of irony seeing this and having a saw that I sold on the bench that is being made right for the purchaser.
It's very hard to diagnose over the internet and the seller should have the opportunity to make it run right if that is agreeable with everyone. You two gentleman need to work this out in some reasonable fashion with each other.
 

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I agree but there needs to be some more transparency from the buyer IMO. The buyer has another saw with low compression and a perfectly good cylinder/piston (according to him). Incorrect compression tester could explain both cases of low compression.

Also, when someone claims the saw has scoring posting a picture of the condition makes perfect sense to me. I'm not knocking the OP but he did say he doesnt have a lot of small engine/2-stroke experience. Maybe the scoring is carbon streaking?

Also, I think it's worth the OP cleaning the points and adjusting the gap if he hasnt tried it already. Who's to say the spark is strong enough? Maybe it's bad plug?
 

Stump Shot

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I agree but there needs to be some more transparency from the buyer IMO. The buyer has another saw with low compression and a perfectly good cylinder/piston (according to him). Incorrect compression tester could explain both cases of low compression.

Also, when someone claims the saw has scoring posting a picture of the condition makes perfect sense to me. I'm not knocking the OP but he did say he doesnt have a lot of small engine/2-stroke experience. Maybe the scoring is carbon streaking?

Also, I think it's worth the OP cleaning the points and adjusting the gap if he hasnt tried it already. Who's to say the spark is strong enough? Maybe it's bad plug?

Especially if an adapter was used, this will give a low reading.
 
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