B&S engine woes, part 2

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Old 11-01-15, 11:31 AM
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B&S engine woes, part 2

I started a thread here over 5 years ago (see http://www.doityourself.com/forum/ou...gine-woes.html) about this engine. At that time, the carb was gummed up and rebuilding it did the trick. It ran great for the past 5 years although I did not use it much in 2015. I think the last time I started it was in the spring.

So I tried to start it yesterday...no luck. I don't think it's the carb this time - I installed a fuel shutoff valve after getting help on the original thread, and ever since then I shut it off by closing the valve and letting the engine run until it cuts off from lack of fuel. Now, the problem is, it has a hard time turning over. So I took the plug out, and it turns over easily. Can smell the fuel in the cylinder, and the plug still has a decent spark too (although, it has not been changed probably since I rebuilt the carb 5 years ago.) But as soon as I put the plug back in, it has a lot of trouble turning over. Basically as soon as it hits the compression stroke, it stops. Holding the starter on, it will eventually get past the compression stroke, turn over for one cycle, and get stuck again on the next compression stroke. To rule out a wimpy battery, I connected my 200 amp battery charger/engine starter...still gets stuck on the compression stroke.

The wire going to the starter was getting very hot after a few of these attempts, so I quit. I'm only an amateur mechanic, but it sounds to me like maybe the starter is just old and weak, and doesn't have the muscle it used to? Does that make sense? Or are starters more of a they-either-work-or-they-don't-work kind of beast? As I said, when I take the plug out, it turns over briskly.
If it is the starter, any tips on where I might find a replacement, preferably on the cheap? This mower is about 12 years old now and I don't really feel like sinking a whole lot of money into it.
 
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Old 11-01-15, 12:04 PM
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Probably need to adjust the valves also make sure all the electrical contacts are clean. Have a good one. Geo
 
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Old 11-01-15, 03:04 PM
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#1 I agree with Geo on the valves need an adjustment.

#2 When I jump a mower I go straight to the starter terminal. I jump with cable from my truck. I don't use a charger to jump start.

#3 I did read your original post and I would use a gunsmith screwdriver to take the jets out. They are common nowadays.
 
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Old 11-01-15, 04:31 PM
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I agree with both above replies.
 
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Old 11-01-15, 05:12 PM
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Actually I meant to say the valves MIGHT need adjustment, but since it's that age it might be in order for a good tune up.

Cheese I need to know how can I post a profile pic on here ??
 
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Old 11-01-15, 08:06 PM
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I'm going to look at the valves tomorrow. I'll follow up with what I find. What else comprises a "good tune up" other than obvious things like a new spark plug, changing the oil & filter, air & fuel filters?
 
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Old 11-01-15, 10:47 PM
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Most likely the valves are the problem. There isn't much to "tune up" on a modern engine these days. Clean the carb if needed, replace the plug and air filter if needed, adjust the valves... that's about it.

BoudreauxEunice, click on your name, go to profile, click edit profile, and add it there.
 
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Old 11-02-15, 03:00 PM
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So I took a look at the valves and sure enough there was at least .010" clearance on both of them. The manufacturer calls for .003-.005 on the intake, and .005-.007 on the exhaust. I took them both down to .003. Although, to be honest, the .004 shim fit in there too, just a little extra snug. So they're set for somewhere around .003-.004. Push rods looked to be in good condition.

Gapped and put in a new spark plug, an NGK that "superceded" the old Champion according to the guy at the tractor store. Battery was still dead even after an overnight charge, so I just used the battery charger to jump it again. It got stuck on the compression stroke again, but, holding the starter on, it got past and did NOT get stuck at the next compression stroke, as it was doing before. As soon as it started cranking, it started, and ran well. Good enough. I bet with a new battery in it, it will turn over easily with no hesitation at the first compression stroke.

So I'm up and running thanks AGAIN to you awesome folks. Glad I didn't waste my money on a new starter when that wasn't what it needed.

Oh, I also reused the existing cover gasket as it was in decent shape. I ran a ring of RTV silicone around it just to prevent any leaks.

Thanks again for the help!
 
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Old 11-02-15, 03:41 PM
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Glad you got it! Thanks for the update!
 
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Old 11-02-15, 04:03 PM
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Glad you got it going, but I dont know what happened to my post on the valve clearance.

I do 5 and 5 or 4 and 6 ~!~!
 
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Old 11-02-15, 04:03 PM
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Success is a wonderful sound. Have a good one. Geo
 
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