Snapper 21" white handlebar super mower

[slomo]

Got an old Snapper 21404P that's probably mid 1980's era. Still cuts and runs perfect. Ok nothing new there. You Snapper guys know the drill.

Issue is the mower has a nasty vibe to it. Has a new OEM Oregon 99-121 Super Mulching blade and the Extreme Ultra carb clean. Fresh oil, both air filters are new and plug cleaned. Deck is clean and again blade is new. Thinking previous owners must have hit something in the yard? Unless the blade is somehow a dud? Crankshaft is the next thing. I put anti-seize on the blade bolt and torqued to 40 ft lbs.

Engine is the stellar Briggs MAX Series (prior to Quantum) 4hp 190cc Super Engine. The oil stays crystal clear/clean. Amazing from a 35 plus year old engine. Doesn't use any oil either.

The vibe is there from idle to max revs. Thinking bent crank? What do you guys think? Could swap in another new Oregon blade to rule that out. What is the best way to check for a bent crankshaft?

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[Hammermechanicman]

Turn mower over. Measure tip of blade to bottom edge of deck. Rotate blade 180 degrees till tip other blade tip is in same place. Measure that blade tip to bottom of edge of deck. Should be exactly equal. Any difference crank or blade is bent.

 

[slomo]

Turn mower over. Measure tip of blade to bottom edge of deck. Rotate blade 180 degrees till tip other blade tip is in same place. Measure that blade tip to bottom of edge of deck. Should be exactly equal. Any difference crank or blade is bent.

That's what I was thinking. IF the crank is bent, only way to repair is a new crank and possibly engine block? There are no lower bearings in these Briggs motors right? Not like a Kawasaki or Wisconsin Robin. Probably a lower sleeve if that?

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[Hammermechanicman]

I have an in the engine crankshaft straightener. Haven't used it in many years.

 

[Scrubcadet10]

Taryl Fixes All has a video how to straighten Cranks.

 

[slomo]

I measured the blade from the upper deck location. It's exactly 1.5" on both sides of the blade. My new blade seems okay. Tried moving slash wiggling the blade adapter and crank. No obvious movement found. Then I pressed harder on the blade. I "think" I might have see a tiny tiny bit of movement but the mower moved a little bit with that too. So I couldn't be sure because I was really pressing on it.

I cleaned the carb. Thought it was say the pilot circuit not fully open/dirty. I removed the emmulsion tube and blew out with my air compressor. Chased all holes with a nylon bristle. Carb should be clean. Tried adjusting the pilot screw. Though something was out of adjustment. Found that didn't smooth the engine out. There is a needle that protrudes up through the carb bowl for the main jet I think. Has a flat blade slot on the needle and a spring above the slot. It's a spring loaded main jet adjuster. There was no new seal for that one so I did not adjust it. So I put it back roughly where I found it when I cleaned the carb. Guess I could try tweaking it a bit to see if it would smooth out the engine. This Briggs carb is no longer made. It's not leaking right now so I'm scared to mess with the main jet needle.

Engine is a Briggs - Model 111702 Type 0166 01 Code 89012728. What do you guys think?

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[slomo]

When you look up the carb rebuild kit, it says part #125 for the entire carb. Then in the part description it says "fixed main jet". This one has an adjustable main jet needle. Also the part # has 2 listings for part 125. Both have the final same part number for the whole carb of 492544 (discontinued).

Guess since this MAX series Briggs is the previous series to the Quantum, I could take a quantum carb and try it? As long as the O-ring gasket lines up and mounting screws go in. Then there will be a carb linkage issue.

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[Scrubcadet10]

I saw in the Parts tree diagrams, it seems multiple type carbs were used maybe....
carb kits:

• Carburetor Overhaul (For Lms-1,2)
• Carburetor Kit (For Lms-3,4)
• Carburetor Kit (For Lms-5,7,10) Note: See Carburetor Illustration For Location of LMS I.D. Number
• Carburetor Overhaul (For Lms-11,12,13,14,15,m26)
• Carb assembly
• Carburetor Assembly (Fixed Jet) (For Lms-12)
• Carburetor (Fixed Jet For Lms 2,4,7,12)

 

[slomo]

Forgot to look at the other carb page.

Parts Lookup

shop.briggsandstratton.com

Show "adjustable needle valve" with carb part 491002 again discontinued.

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[slomo]

Guess I could also have the wife lower the handlebar with it running a few degrees. Then I could look at the blade with the engine running. Surely with a handlebar numbing sensation I could see something. Have to tell her to not put the handlebar to the ground and starve the stellar Briggs of oil.

slomo