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You are watching: Briggs and stratton 12.5 hp engine compression


I have a Briggs 12.5 hp motor that was give to me through a siezed up exhaust valve. Ns took the motor partly apart to change the valve and valve spring. Ns reassembled the motor through the cam and also crank sprockets set per your marks. I have actually fuel, spark, air/exhaust, yet the motor refuses come fire up. I have sprayed ether to see if it would fire turn off that, and also have even sprayed ether in the burning chamber and also tried it that way. Tho no fire. Through the plug wire removed and also engine cranking, I have a good spark. I have actually fuel inside the carbohydrate bowl and also can feel the exhaust pumping out of the muffler. Does anyone have actually an idea what would store this engine indigenous firing?
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I ran a compression test and have almost no compression. It additionally leaked down nearly immediately. I"m assuming I"m going to need to replace the rings and also lap/grind the valves too. Any kind of ideas/suggestions?
What room the engine numbers? Model, form and code.It"s tough to acquire a compression reading from Briggs & Stratton because of the compression release. Inspect you valve clearence before you perform anything else. Should be in between .004 and .006 because that both valves.
Set the spark plug void at .060, that will simulate the spark plug gift under compression and also fuel conditions. Just due to the fact that the spark plug fires laying top top the head bolt or muffler doesn"t mean it"s sparking inside the combustion chamber. Checking the valve clearance has to be done as soon as installing a brand-new valve. Examine the clearance in in between the valve tappet/lifter and also the valve stem that sticks out of the spring. There need to be clearance there once the valve is every the way closed and also the piston is at height dead center on the compression stroke.Does this engine have a actors iron sleeve in the cylinder?With the number you just gave ignore the clearances I provided in the prior post, I assumed this to be a smaller sized engine.
I will examine that valve clearance and see if that is the problem. It may take a couple weeks once I acquire the time though. I evaluate your help. Thanks!
Have you confirm that the paris wheel key way matches the key way ~ above the shaft, the spark native the mag has to arrive at a specfic time. If off, it will never ever ignite when its expect to.

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Hi and also welcome come TSF jamez46I i think they have actually it established by now as this is a two+year old thread.BG
I had an atv that quit running on me, and also even despite I had actually spark in ~ the plug end, I needed to find out is there was spark in ~ the other end of the plug, i m sorry turned the end that there was not. I just used one allegator clip to affix the cathode the the plug to gnd, cranked the over and also no spark. Changed the plug and also all is well.
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