MF 65 rough running

TPHIL · Aug 2, 2018

I bought a somewhat freshly rebuilt Massey 65. I was brush cutting and all of a sudden it started to run terribly rough and shooting some black exhaust out of the exhaust. I have checked plugs for spark and the carb but everything looks good. Any ideas? Jets are set to factory settings also

old · Aug 2, 2018

Checked plug for spark but was the spark a good blue/white in color and able to jump a 1/4 inch gap or more?? If not you have a spark problem. Where the plugs black and sooty or black and oily?? A plug should be a sort of brown in color if working as they should be.
Checked carb as in how?? It could have some rust/dirt in the needle seat making it so the float will not close like it should. You might try pulling the carb drain plug and make sure you have a good steady flow of gas that will fill a pint jar in less then 3 minutes and yes catch the gas so as to look for rust/dirt/water.

Also when was the last time you serviced the air cleaner and dumped the mud and water and filled with fresh oil??
Any one of these can be your problem as well as a few other things

TPHIL · Aug 3, 2018

(quoted from post at 21:55:51 08/02/18) Checked plug for spark but was the spark a good blue/white in color and able to jump a 1/4 inch gap or more?? If not you have a spark problem. Where the plugs black and sooty or black and oily?? A plug should be a sort of brown in color if working as they should be.
Checked carb as in how?? It could have some rust/dirt in the needle seat making it so the float will not close like it should. You might try pulling the carb drain plug and make sure you have a good steady flow of gas that will fill a pint jar in less then 3 minutes and yes catch the gas so as to look for rust/dirt/water.

Also when was the last time you serviced the air cleaner and dumped the mud and water and filled with fresh oil??
Any one of these can be your problem as well as a few other things

Plugs were dry and sooty
I took carb apart and everything was clean and new. Which I expected because I believe it was rebuilt maybe just a couple months ago, spark color looked good but might be a little weak. I will have to recheck.
I pulled air intake tube off the filter to rule that out.
It was just very sudden when it happened, it was running fine and in just a second started to miss and smoke.
Coil has juice and points and condenser are also new

old · Aug 3, 2018

Well to start with you need to clean the plugs or replace them. As for running rough and smoke sounds like you had some rust/dirt in the fuel system which caused the float to hang up and cause it to run way to rich. Or the points are going bad so weak spark which can also cause it to run poorly and rich

MF 65 rough running

TPHIL

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old

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TPHIL

New User

old

Well-known Member

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