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Discussion Starter · #1 · (Edited)
I have a Craftsman 6.25hp push mower - model 917.388350. It has a Tecumseh engine - model 143.006200. It has always run great but the breather valve was loose and it was allowing oil to leak out and spray all over the engine. The breather tube was also weak and pinched.

I finally decided to replace both the breather assembly and breather tube which required removing the flywheel. I replaced the parts this evening and changed the oil and started it up. It runs terrible now...slow and rough. I didn't make any adjustments to the carb so I'm not sure what the problem is. Is the breather tube supposed to be pinched like it was? That's the only thing I can think of that is different now. If anyone has any advice I would really appreciate it.

Thanks
 

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Discussion Starter · #3 ·
The flywheel key looked perfect so I didn't bother to replace with a new one. It only smoked just a tiny bit around the muffler when I first started it up.
 

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Discussion Starter · #5 ·
It starts with no problem but it never picks up speed...sort of like a rough idle. It does seem like a timing issue now that you mention it. What could I have done to throw off the timing? I did have a hard time removing the flywheel. I ended up buying a harmonic balancer puller and it came right off.
 

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Try running it without the air filter element installed. If it runs better, then you may need a new air filter element.
 

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Discussion Starter · #8 ·
I did not have to remove the ignition coil. I tried running it without the air filter and there was no change in how it ran. I also ran it without the gas cap and this did not make a difference either.
 

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Check the breather tube and make sure it's not binding or interfering with the governor arm or throttle linkage.
 

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Discussion Starter · #10 ·
I checked the breather tube and it is not binding or kinked and it is not interfering with the governor arm or throttle linkage.

I had a couple more thoughts. Before I replaced the breather assembly there was a lot of oil and gunk caked on the engine. I used a degreaser and sprayed with a hose. I wonder if water or a piece of grime got some where it shouldn't have. I also tipped the mower up on its side several times before I drained the oil...i'm not sure that would cause a problem though.
 

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Perhaps some water got in somewhere and is causing some problems. Check the throttle on the carburetor and make sure it's free and not stuck at a low speed setting. Check the spark plug and make sure there is no moisture on it. Water may have made it's way into the float bowl and could be plugging the main jet.
 

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Discussion Starter · #12 ·
Still no luck... I put a different sparkplug in it and removed the main jet and bowl. There was no water there and the main jet looked clean. The throttle moves freely and is not stuck. When I start it up I can see the throttle adjusting back and forth with the roughness of the engine.

I guess my next step will be to remove the flywheel again and take another look at the flywheel key. Maybe I overlooked something.
 

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Discussion Starter · #13 ·
Ok, I took the flywheel off again to check out the flywheel key one more time. The flywheel key is in good shape.

However, when I was taking the flywheel off I happened to notice something that got me wondering and I think may be the problem. The tab that the governor spring is attached to is bent forward (towards the air filter) to probably a 40 or 45 degree angle. It's a possibility that I accidently bent this tab when I was initially trying to pry up on the flywheel to remove it.

Is the tab bent forward too much and could this be the problem that is causing the mower to run slow? If so, how far back should I bend it? How do they come set from the factory?...straight up and down?

Thanks!
 

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You really need a tachometer to set the engine RPM's, but that could definitely be the problem. Bend the tab a little to put some tension on the spring and see how the engine runs. If it improves then this is likely the issue on your engine, then it just needs to be bent to obtain the correct operating RPM's.
 

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Discussion Starter · #15 · (Edited)

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Listen to your neighbors mower, yours is right if sounds like his/hers or somewhere close, the slower. the longer the engine lasts, the faster, the shorter. This is not rocket science, keep the blade sharp and run it as slow as it will cut your grass to your satisfaction, you don't need to buy a tach for that. Have a good one. Geo
 

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Pic

I recently removed and cleaned my carb, but I think I have the throttle link and the spring do-hickey backwards. Can someone post a picture of the right way?

917.388350
 
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