Craftsman DYT 4000 backfiring constantly PLUS battery does not charge

As in the subject line--the v-twin, engine (Briggs and Stratton type 445777 0168 E1) in my DYT 4000 backfires constantly when running and the battery doesn't charge. I've tried various things with the backfire problem: Replaced the air filte r and cleaned the foam pre-filter; replaced the spark plugs; replaced the c arb bowl gasket and needle; soaked the carb in carb cleaner while I was get ting the parts. Put it all back together. Nothing helped. As for the recharging problem, I have no idea where to start. I assume tha t there's a generator somewhere.
Any help appreciated. Keith snipped-for-privacy@yahoo.com
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I guess it used to work ? Backfiring through muffler or air filter ? Usually a series of magnets and coils making juice. I don't know if timing can cause backfire. I don't think valve adjustment would cause it.
Greg
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wrote:

Generator coil is under flywheel, find the wires where they come out, check for AC voltage there. Then check diodes, Check for DC voltage after diodes. Look for broken wires.
Backfire could be because timing is off, that is set by the key in the flywheel, or it's very lean. Most likey lean, gasohol is putting all kinds of deposits in carbs. I have found no amount of soaking will help, disassemble and clean, torch tip cleaners work great for all the little holes. Buy a complete carb kit the one that comes with the welch plugs, you will need to remove them clean the passages behind them and put in the new ones.
Question: will it idle? if yes then idle pasasages in carb are OK. you may not need to pull the welch plugs.
Question2 : if you choke it alittle does it stop back firing?
one more thing, engine needs to be at full RPM to charge, if it's running poorly that could be why it's not charging.
Remove 333 to reply. Randy
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On Friday, June 6, 2014 9:39:37 AM UTC-4, Randy333 wrote:

Backfiring is usually a symptom of an electrical problem. Given that he also has a problem where the battery isn't charging, I would suspect something is intermittent, as opposed to the timing being off. If the power to the ignition electronics is intermittent you can be getting spark at the wrong time too and then the backfiring.
Most likey lean, gasohol is putting all

I agree. If the carb is suspect, I'd get the rebuild kit. They are usually available on Ebay for $10 and they include new gaskets, needle valves, welch plugs, etc. A shop manual or maybe a youtube video can be a help too. The rebuild kits usually don't include the gasket that mounts the carb to the engine, so buy one of those separately.
But again, given the symptoms, I'd suspect electrical problem first.

I was wondering that too. If it's not running, then how does he know it's not charging? If it has a dead battery and he just jumps it or something to get it going, and then it has a faulty charging system, that's not properly supplying ignition power, that could give you the backfiring. If the battery is fully charged, then I would think that should supply steady ignition power, until the battery finally runs down.
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Probably the first backfire sheared the woodruff key on the flywheel and now it is off center and causing timing problems. When and if you pull the flywheel check to see if the half moon key is damaged and needs replacing to accurately align the flywheel.
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On Friday, June 6, 2014 11:04:15 AM UTC-5, EXT wrote:

Well, as per the original post, the engine backfires WHILE RUNNING--and I s hould have included that it was backfiring through the muffler, sorry. In a ny case, I put some HEET with fuel injector cleaner in the gas, suspecting that I might have water in the gas but too lazy to pull the tank... then st arted it and sprayed carb cleaner down the carb throat while it was running . In a matter of seconds the backfire went away and now it runs smooth aga in. However, it still doesn't charge. As I noted in my comments, I don't think the starting circuit or recharge circuit has anything to do with igni tion. This engine has magnetos just like a little pull-start motor on a pu sh mower. I believe the generator is just to recharge the battery, no? I'm not an expert, so don't get upset with me, but when I take the engine cove r off, I see the same kind of ignition system that my push-mower has with p ick-ups mounted next to the spinning flywheel and spark plug wires coming o ut of them. If you disconnect those pick-ups they snap right onto the flywh eel, i.e., they're magnetic. There is no coil or distributor, points or con densor, so it looks like a simple magneto system. Keith
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If the engine is old, it will have points to control the timing and a condenser, but they are under the flywheel. Newer engines use electronic ignition that uses the magneto to power it, again timing and the electronics may be under the flywheel also. No matter which system is used if the flywheel is out of position the timing will be all screwed up.
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On Sat, 7 Jun 2014 11:06:32 -0700 (PDT), snipped-for-privacy@gmail.com wrote:

and the charging system has nothing to do with the ignition. The charging system will be either single phase or 3 phase AC (1 wire or 3) and the output is rectified to DC and regulated by the rectifier/regulator unit. If it is a single wire you can test it by connecting a headlamp bulb. It will glow on AC or DC. If it has 3 wires, an AC voltmeter between any 2 or any one and ground should give you a reading (these tests all done with rectifier/regulator disconnected. The rectifier/regulators are notorious for failing. If no load is connected they need to dissipate the entire output of the "alternator" as it runs full-on wide open all the time.
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