# Briggs/Stratton 12hp Power Built - Starting Problems



## one_sad_episode (Sep 12, 2007)

Ok... First here's the specs:

12HP Briggs Power Built - Vertical Shaft
Model: 282707
Type: 0110 01
Code: 9503284D

Here's the story... I got a riding lawnmower from a buddy. His grandpa put gasoline in the oil filler the first or second time he started the engine (brand new). He ran the engine and within minutes the engine had seized.

My buddy gave me the lawnmower in trade for some other work. I completely tore the engine apart, had the machine shop do a max bore. Got a max bore piston and a rebuild kit. I put the engine on a test station and it fired right up. 

I let the lawnmower sit for about a year because it needed some other minor work. In this time the carb had varnished up and would no longer operate the engine. 

I bought a brand new carb and installed it today. I was told by the small engine shop that it was a fixed jet and did not need calibration. I bolted the carb up and this is where I am now. I can't get the damn thing to run. I have made a video showing exactly what it's doing:

http://server10.myebiz.com/dubnet/100_0564.mov

The video is like 20mb... but please be patient with me and help a fellow out. In the video I start by choking the engine and I get back fires through the intake... each time the engine turns it looks like it's almost spraying fuel and air out of the intake. I spray ether into the intake and crank it over... the engine fires up momentarily and dies... like it's burning of the ether then stopping. This tells me that the engine timing and compression is still good. So it must be a fueling or possibly a spark issue. I have checked for spark and it has a good spark (got shocked in the process).

Anyway... I guess my question is, what the hell do I do next? Any ideas, points, tips or whatever. What type of adjusting should I do on this "fixed jet " carb?

THANK YOU in advance. :thumbsup:


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## 30yearTech (Sep 14, 2006)

You could have a sheared flywheel key, this will advance the ignition timing and could be causing the backfire. You have a solid state ignition on this engine so it will spark regardless of the condition of the flywheel key.

Another possibility is a sticking intake valve.


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## one_sad_episode (Sep 12, 2007)

Good ideas... I'm headed out there now to see if the key way is broken. Maybe I'll take the head off and see if the valve is stuck. 

Thanks 30.


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## pyro_maniac69 (Aug 12, 2007)

I'd say theres a good chance the intake valve is stuck open


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## one_sad_episode (Sep 12, 2007)

30, you were RIGHT on the money. The keyway had sheared. I was so sure it was the valve, and I took the damn head off to see that everything was allright.... I guess you should always try the easiest thing first, then proceed to the harder things.

I fixed the keyway, bolted the flywheel back on and she fired right up without hesitation or complaint.

Thank you for the wonderful ideas, gentlemen.


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## pyro_maniac69 (Aug 12, 2007)

holy crap, can't say I seen one turned that much


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## one_sad_episode (Sep 12, 2007)

Yeah.. I was quite amazed, myself. Funny thing is... I put this engine away in RUNNING condition. I get it out and it didn't work. Oh well... what do you do, right?


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