M18 vs. M20 question
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Tunames
- Posts: 14
- Joined: Sat Nov 16, 2013 4:11 pm
- First and Last Name: Steve George
- Location: Shawnee, KS
M18 vs. M20 question
I have an 1812 with 900+ hrs. I also have a 2072 with 600 hrs. I just got last fall. The m20 in super runs so smooth compared to the m18 in the 1812. Its ran like that for the last 7 yrs. Is that typical of the 18's and 20's? Would the 18 be in need of a rebuild? or would it be better to repower it? and with what? I've always liked the 1812 but I'm REALLY liking the 2072! Advice and opinions welcome....
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Jlaws
- Posts: 1141
- Joined: Sun Sep 05, 2010 10:14 pm
- First and Last Name: Jess Laws
- Location: Independence , Ky
Re: M18 vs. M20 question
I don't know why one would run smoother than the other , they're basically the same engine .
By smooth are we talking engine or something else ? Could be something as simple as carb adjustment .
If were talking something else ,the first thing that comes to mind is maybe the 1812 has an unbalanced driveline which will cause a lot of vibration .
Worn couplings ( ragjoints) or spherical bushing or worn driveshaft ends where it goes into the spherical bushings .
Loose engine bolts where it bolts to the engine plate or missing the spacers that go between the engine and plate and throw the driveshaft out of alignment .
Yeah I've bought a couple of Magnum twin cubs that previous owners have left them out , and have worn out spherical bushings and couplings in short order .
900 hrs on a magnum isn't a lot of hours if its been maintained , I've gotten 1600 + hrs out of them without a rebuild .
By smooth are we talking engine or something else ? Could be something as simple as carb adjustment .
If were talking something else ,the first thing that comes to mind is maybe the 1812 has an unbalanced driveline which will cause a lot of vibration .
Worn couplings ( ragjoints) or spherical bushing or worn driveshaft ends where it goes into the spherical bushings .
Loose engine bolts where it bolts to the engine plate or missing the spacers that go between the engine and plate and throw the driveshaft out of alignment .
Yeah I've bought a couple of Magnum twin cubs that previous owners have left them out , and have worn out spherical bushings and couplings in short order .
900 hrs on a magnum isn't a lot of hours if its been maintained , I've gotten 1600 + hrs out of them without a rebuild .
I see a lot of cub cadets while going down the tracks , its a shame I can't pull over and ask about them .
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Tunames
- Posts: 14
- Joined: Sat Nov 16, 2013 4:11 pm
- First and Last Name: Steve George
- Location: Shawnee, KS
Re: M18 vs. M20 question
Definitely engine I've rebuilt carb (walbro fixed main jet) fuel pump is good,good consistent spark. I haven't pulled the heads to decarbon. I've started running sea-foam in the gas seems to help but still sounds like one cylinder cuts out intermittently sorta. I just thought it was normal for the magnums! Until I got the 2072....
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Tunames
- Posts: 14
- Joined: Sat Nov 16, 2013 4:11 pm
- First and Last Name: Steve George
- Location: Shawnee, KS
Re: M18 vs. M20 question
Just checked compression 88lbs. Both cylinders.....at least it's even. I'll pull the heads off ans see how it looks inside hopefully get away with a good cleaning and some new gaskets
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bbaker
- Posts: 777
- Joined: Mon Sep 06, 2010 8:47 pm
- First and Last Name: Bryan Baker
- Location: Evansville IN
Re: M18 vs. M20 question
You might have an intake gasket leak as well. That will cause one cylinder to mis-fire. Also as far as I am concerned the fixed jet carbs are junk. I have several of them and they either seem to work or they don't. Contact Ray Weaver, or Rich Patton and get an adjustable carb from a Kt-17 or Kt-19. Rebuild that one and get it tuned right and I'm sure you'll be surprised how much better your tractor runs, but how much better and slower it will idle.Tunames wrote:Just checked compression 88lbs. Both cylinders.....at least it's even. I'll pull the heads off ans see how it looks inside hopefully get away with a good cleaning and some new gaskets
I wouldn't bother with the heads at this time unless you just really want too. A little carb cleaner sprayed around the intake joints will usually quickly tell you if one is leaking.
Cub Cadet, John Deere, New Holland, bobcat, Chevrolet, and Harley Davidson just a few brands I'm proud to own.
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Racenitro
- Posts: 354
- Joined: Tue Sep 07, 2010 10:31 pm
- First and Last Name: Frank S. Morski
- Location: O'Fallon, Il
Re: M18 vs. M20 question
Jess and BB are both right on. Both Magnums usually run very smooth. I have had a lot of both and it is hard to tell apart even on power.
BB is right about the carbs. If the carb is not right it will cause a lot of trouble.
I have had a tiny piece of lint in the jet of the carb and it will run like sh&&. You may want to recheck the carb and make sure all the passages and jets are really clean.
Also, check your plug wires...a bad one will cause it to run rough and appear to have one bad cyl.
There is no comparison to a 2072. The power steering makes them a dream to work with. I have two that I mow with weekly. Not worn out when I am done mowing 3 acres. Course the 1572 is easier on fuel.
BB is right about the carbs. If the carb is not right it will cause a lot of trouble.
I have had a tiny piece of lint in the jet of the carb and it will run like sh&&. You may want to recheck the carb and make sure all the passages and jets are really clean.
Also, check your plug wires...a bad one will cause it to run rough and appear to have one bad cyl.
There is no comparison to a 2072. The power steering makes them a dream to work with. I have two that I mow with weekly. Not worn out when I am done mowing 3 acres. Course the 1572 is easier on fuel.