Carburetositelock

"MM54" (mm54mk2) 04/22/2018 at 11:46 • Filed to: tractorlopnik

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Trying to make the tractor not require a fine balance between choke and throttle (which changes as it warms up) to stay running. No idea if/when this carb has been previously messed with.

Duck Duck Grey Duck FTMFW! > MM54 04/22/2018 at 12:02

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Looks like never is the last time it was worked on.

HammerheadFistpunch > MM54 04/22/2018 at 12:57

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Having the same problem with my generator

Stephenson Valve Gear > MM54 04/22/2018 at 16:05

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Briggs & Stratton updraft? Dumb question, but did you try adjusting it? They can be a bit finicky. I like to set the main jet on the lower right first (should be able to go wide open without bogging or flooding), then adjust the idle mixture screw sticking out the right side of the venturi next to the air cleaner base. Adjusting the main jet WILL affect the idle mixture. Idle speed can be set after that.

Remember that if you want to pull it apart at the bowl, you need to remove the main jet adjustment on the lower left, then use a small straight blade screwdriver to remove the brass tube that goes up at an angle to the idle circuit. They tend to get stuck... be careful and sacrifice a screwdriver by grinding it to fit the slot in the end of the tube exactly so it doesn’t mess it up...

MM54 > Stephenson Valve Gear 04/22/2018 at 16:44

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Yessir. I fiddled with it, but the tractor sat unused (with gas in it) for years and always acted like it was full of varnish after I revived it late last year. Forget about idling, it had one speed which, with constant tweaking of the throttle and choke, would keep it running decently (this point changed with load and engine temperature).

I got it torn down today and discovered that the idle screw is broken off. Looks like it was tightened in the whole way and the needle stuck in the seat and twisted off. I’ve been unable to get the broken bit out (I have a new one) unsurprisingly, so it’s looking like I may have to replace the upper section of it. I’ll probably order a “new” carb off amazon this evening and put that upper part on my lower section with the appropriate jets and so on. Quite a bummer when I realized why the idle screw looked so funny (and explains why it never idled).

Stephenson Valve Gear > MM54 04/22/2018 at 16:55

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Sounds like you have a good handle on the problem(s). Very irritating to pull it apart and find an adjustment screw broken off! Looking forward to seeing your progress...