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Hi guys, just joined your site from down here in Australia. I recently acquired a Greenfield rideon which is powered by an 11HP briggs ( model--253707 type--0169-01 code--86010211 ) my problem is it is contantly backfiring thru the carby and has no power under load. It will start and run but very rough and soon as you engage the blades backfiring gets worse and it will die. I have check the key on flywheel it's spot on---have relapped valves and checked clearances (.007 inlet---.011 exhaust )---have cleaned and checked carby everthing seems fine--airgap coil to flywheel .010-- pionts--.020--plug--.030---I'm running out of ideas--could it be the condensor or coil causing it to fire at the wrong time--would love to hear your input I'm just about over playing with it.Thanks Paul.:confused2:

I think your problem is still in the carb,did you put a rebuild kit in it or did youwash it out?

Hi redfish, Thanks for the reply---Yeah I put new kit in carby and also put carby off my son's 12HP which was running fine---did exactly the same---put it back on his motor runs perfectly. That's why I'm scratching my head---think it must be electrical---unfortunately his motor is electronic mine's older points set up. Thanks Paul.:confused2:

check for a partially stripped key on the flywheel. it will be very slight>:thumbsup:

Nice to see another Aussie on here

How is the carburettor tuned? Have you adjusted the mixture screws?

Breaker points could be getting weak? I would retrofit a second hand magnetron coil onto it.

Also, you lapped the valves but were the valve seats square? If valve seats not cut it could still be leaking through valves?

Hope that gives you some ideas.....

Hi John, Thanks for the input but I did go to alot of trouble to make sure keyway was lined up spoton before I locked it down---have pulled flywheel back off to check but no---still lined up spoton. Thanks Paul.:confused2:

Hi Ozranga, Thanks for the ideas---I have main jet out 1 turn idle screw 1.5 turn this is where it seems to run smoothest---after I lapped valves I filled bottom half of ports up with WD40 --still there after 1 hour later. Points do look abit sus but it fires up very easly. Is that coil you're talking about off an electronic setup. Thanks Paul.:confused2:

What you have done sounds good.

Yes the Magnetron is the Electronic Ignition..... If you can get hold of one its an easy swap.

Just cut the wires to the breaker points and leave points in so it doesnt leak oil through the plunger.

Work out where the wire is that stops the mower that goes to the ignition system now, put a terminal on that wire to become your new stop wire on the electronic ignition version coil

Set the air gap at 0.008' to 0.010' and there should be no more ignition issues

In saying that I am still not 100% certain it will resolve your issue, although it will improve the reliability.
Edit**
Worth a try....just reading back through your issues and I would change the coil.

P.S How old is the fuel in the mower?

I'm going to throw my two cents in and say to check the muffler as it may be partially restricted. I was helping a neighbor the other day with his string trimmer and it was "spitting" out the carb and was not operating at full speed. After a carb kit and new fuel lines (both bad) we removed the muffler and the problem went away. Now I fully realize that we are comparing two stroke engines to four stroke but the symptom seems the same so this is just one more option to rule out. Where I live there are insects that will build a nest of mud just about anywhere and I've found them in O.P.E. mufflers. Try a known good muffler and see if that helps.

Good luck,

Lawnranger

Hi Lawnranger, Thanks for your two cents worth (which is also a saying we use quite often down here in Oz) Muffler seems to be clear when running --have had it off and can blow compressor thru it easly but maybe I'll fire it up with no muffler at all and see what happens Thanks Paul.:confused2:

Hi Ozranga, Thanks for the idea I'll get on ebay and see if I can find a coil---I'll try anything---regarding fuel--tank is clean and brand new premium fuel Thanks Paul.:confused2:

If you cant find one PM me and I will source my contacts

As per adjusting the mixture screw out 1 and 1/2 turns...why not go ALL the way out to where it's blowing black smoke and running, then lean it out gradually until it runs at its best RPM? That's what I do on both push mowers and riders, weedeaters and anything else. Can't always go by the book, except for a ballpark figure/starting point. Surely couldn't be a sticking intake valve? Symptoms still sound like a timing problem eh? Since the key is OK, then it couldn't be that. I had a 5 HP old B&S start up fine, then got hot and started cutting out. Intermittent sticking intake valve was the culprit. Sounds like a mean Grimlin in there, mate! Concerning the coil, it could be intermittent as well. Try putting a known good coil on it, see if it runs then. Good Luck! Dave

I have 11hrs Briggs&Stratton backfires through carb and won't start. I check the key in flywheel and it gets plenty of fire and and gas. when it was
running it backfired real loud and stop running. cannot figure it out:thumbdown: