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Old 06-03-2013, 05:05 PM   post #1 of 9 (permalink)
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Default 3.5 HP B&S carb questions

I have a snapper self propelled mower (V212P) from about 1978 with a 3.5HP B&S (92908). I took the carb and tank completely apart and cleaned it good and then replaced the diaphragm when going back together. I have 3 questions. 1st, what is the initial adjustment for the fuel mixture screw? All the way in and then a turn and a half out? 2nd, how do I go about adjusting it once its running and hot? Turn out till it runs rough (to rich) and then turn it in till it seems to run smooth? I adjust at full throttle i'm assuming? And 3rd, when I had it apart, there was quite a but of play between the choke butterfly valve shaft and carb housing. Will this really hurt anything since one end fits into a blind hole and the other end has the linkage cover and gasket over it? My concern was a vacuum leak around the shaft. Throttle shaft only has a tiny bit of play in it. I don't have a manual and havent touched a carb in years ( diesel mechanic:-) )
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Old 06-05-2013, 03:59 PM   post #2 of 9 (permalink)
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ok guys, I got it back together and just wung it. I started with the needle valve adjusted 1 1/2 turns out and thats where it seems to be the happiest. I ran it and got it hot, and it seemed if I went a quarter turn in either direction, it would start to stumble just a little bit and engine speed would drop slightly. Unfortunately, I don't think a dirty carb was the issue. I bought it a few months ago, and ever since, it has taken a few pulls to get it started when cold, and it is super hard to get started when hot. I've actually had to lean the needle valve out close to a quarter turn to get it started, then richen it back up. It acted the same way again after cleaning the carb and replacing the diaphram. I wonder if its as some people here suggested to me and maybe the valve adjustment is to tight, which would require removing the head, grinding the stems to the correct clearance, and putting a new head gasket on it? I also noticed that the center part of my muffler glows red when its running, almost clears up when I richen the mixture to the point that it almost kills the engine, but for the most part, it stays glowing red no matter how the fuel is adjusted. I hate to say it, but I might just have to sell the old snapper that I've always wanted. I know its worth fixing, but money is super tight right now and I don't think the wife would be happy about spending money on a mower that was supposed to be "cheap". It still needs new wheels, the belt from the drive disc to the diff is getting pretty bad looking, and I have a sinking feeling the rod is going out, as some of you may have read in one of my other threads. no noise yet, but the oil gets pretty metalic looking pretty fast
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Old 06-05-2013, 04:01 PM   post #3 of 9 (permalink)
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Oh, and you can add a new blade to the list of things it needs, as the old one looks like its been sharpened so many times, its well past its intended service life.
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Old 06-05-2013, 05:31 PM   post #4 of 9 (permalink)
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Thanks for the update. You could always stick it in the back of the garage and keep it for a "Down the Road Project"
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Old 06-05-2013, 11:10 PM   post #5 of 9 (permalink)
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Ok, I may have jumped the gun a bit. I finally got to mow with it tonight and it ran great. I don't know why tonight was different than the other night,b but it started the first pull when hot, every time and it had good power. Uses less gas than it did before I cleaned the carb too. Still takes 3 or 4 pulls to get it started when cold though. Maybe that is just a by product of it being 35 years old:-) center of the muffler still glows red too, this probably has me the most concerned. I think now that it is running half descent, I'll stick to my original plan and mow with it a few times more, change oil, then repeat again to see if the oil is still turning metallic our if the metal in the first few oil changes was from previous neglect and just needed rinsed out. I love the way this thing moves and cuts though. It feels like it moves lighter than it really is, feels solid for a 35 year old mower, and I love the control of the disc drive self propelled system, turns so easy. Its been leaving some cut blades of grass on the ground instead of blowing them into the bag, but I think a new blade will take care of that, if I can find one, I've heard they aren't made anymore
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Old 06-08-2013, 05:51 AM   post #6 of 9 (permalink)
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Afoulk
Hows the muffler look? worn out? it may just need to be replaced or have some obstructions. The only other thing I can think of that will make a muffler glow is a stuck exhaust valve or one not seating correctly.
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Old 06-08-2013, 07:48 PM   post #7 of 9 (permalink)
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It may just be the muffler, it runs fine for the most party and no popping out the exhaust, so I would think that rules out a burnt exhaust valve. The muffler looks like it could be original, so its a good possibility its shot
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Old 06-08-2013, 08:52 PM   post #8 of 9 (permalink)
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I hope that's what it is, cause that's a cheap, easy fix.
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Old 06-08-2013, 10:16 PM   post #9 of 9 (permalink)
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Quote:
Originally Posted by motorhead12 View Post
I hope that's what it is, cause that's a cheap, easy fix.

that would be cool, I don't have that kinda luck but maybe you will
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