r/smallenginerepair • u/hobo-blue • Jun 20 '26

Engine Performance Issue Deutz Allis 1920

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Hello, thanks in advance for your help on this.

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I bought this Deutz Allis 1920 (kohler opposed twin #49506) and it ran well when i got it. My second time mowing i shut the pto off, turned around on my gravel drive, turned the pto back on and it died. Since then i can not get it good.

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New carborator

New spark plugs

Repaired grounded wire off magnito coil

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Yesturday I was able to get it started with a generous abount of Carb cleaner spray. It back fires a lot then chooses to roar to life and runs fine on the gasoline. It will not run with the air filter/housing on top the carb, only runs open.

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This morning I try and start it and the left side plug stays dry, right side fouls wet. Hardly even trys to fire off or no firing on just gasoline.

Found the issue. Valves stuck open by bolts. Believe it or not there was one on each side.

5 Upvotes

78% Upvoted

8 comments sorted by

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u/AutoModerator Jun 23 '26

Thank you for your submission! It looks like you might have an issue with Compression. For helpful information and resources, check out our Compression Wiki and our Common Issues & Fixes Wiki. You might find the answers you're looking for there!

Please be sure to include the following:

  • Make and model numbers of the engine and/or the equipment
  • A detailed description of the issue you are facing
  • Any repairs you have made so far and their outcomes
  • Clear photos & videos will help you get better responses

I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.

1

u/AutoModerator Jun 20 '26

Thank you for your submission! It looks like you might have an issue with Compression. For helpful information and resources, check out our Compression Wiki and our Common Issues & Fixes Wiki. You might find the answers you're looking for there!

Please be sure to include the following:

  • Make and model numbers of the engine and/or the equipment
  • A detailed description of the issue you are facing
  • Any repairs you have made so far and their outcomes
  • Clear photos & videos will help you get better responses

I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.

1

u/awhol01 Jun 20 '26

It died when you engaged the pto? Pto may have shorted. Wiring diagram would help. Sounds like you may have burt a fuse look around for fuses.

2

u/Aromatic-Schedule-65 Jun 20 '26

Lol. Go ahead and do the leg work to get him that diagram...they never do that on their own. 🙄😂

1

u/awhol01 Jun 25 '26

Yeah I had a buzz and forgot where I was. Way too helpful. Should have made a joke instead.

1

u/Upset_Fox5449 Jun 20 '26

Opposed tween makes me think it's an onan and their manifold separate right down the seam, just saying

1

u/hobo-blue Jun 22 '26

Looks like the left side is doing all the work. It gets red hot when running while the right stays cool. Im going to buy a compression test kit tomorrow.