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Briggs Quiz,


dlcentral

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Heres one we have now that I haven't had time to diagnose yet,,but we have a 10 hp older vert eng243400etc. that turns over fine with spark plug removed,but put you finger or a spark plug in plug hole,and she no longer cranks, hits compression stroke and stops,new starter has been installed,starter when trying to start this gets boiling hot, head was removed,nothing abnormal was found,valves aok not stuck,,breather removed,flywheel key is new,we replaced it,, any ideas?,,And Elon,,dont say because its a BRIGGS!lol,,:o)I think I know what it is,but lets see if you guys do?888
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My guess is a bad ground connection from starter to engine. Could be loose at neg connection to frame. Starter has to have power to get hot. Problem could be no where to go. Interesting, what?? Conrad
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All the older Briggs had the cam lobe ground for easy spin starting. However, a new starter should turn it over either way. Besides, I doubt if the start part of the lobe would be worn as it's not the highest piont on the lobe. I'll go with Conrad on this one, bad/ dirty wireing.
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Don't really know anyting about briggs, but My uncle has a MTD with a 14.5HP brigs that did that same thing turns out the valves werent set right, and the diode was bad in the charging system, so the battery would not charge so my guess would be either Valves not adjusted right or the Battery not fully charged. I also had this problem with my 16 HP kohler, turns out the valves were not set right so the ACR wasnt working.
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quote:
Originally posted by BLT
Older Briggs' have no compression release that I am aware of.
Bob, they didn't have a separate compression release system, but the "Easy Spin" starting was a special grind on the cam lobes that partially opened the exhaust valve at low RPMs so that the engine would turn over easier. Otherwise, they were quite difficult to get over the "compression hump" when trying to spin them with a low-torque starter/generator, or a rope... At higher RPMs, when the engine was running and the cam was spinning fast, this grind didn't really interfere with the proper timing of the valve opening and closing...
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quote:
Originally posted by Jovee
Going to second the muffler plug. Had it happen on 2 strokes. Anything is possible I suppose.
I had it happen to a catalytic converter once, also, but I don't think they were concerned about emissions back then... :D [img]http://www.simpletractors.com/images/b_attachments_images/fogger.jpg[/img]
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Kent, I don't go with compression release. I have been running a 243431 for years with the compression release bump filed off for over 15 years. It starts great with the standard S-G. I just have to keep a good belt and it has to be tight or it will slip. I also don't believe it is too much compression. I have also run engines with .060 shaved off the head. They still start fine. In fact, your finger should not be able to hold enough pressure to stop the engine from turning over if everything else if correct. I will go with a battery that is weak, or a bad starter solenoid. Low voltage causes the starter to pull more current and get very hot.
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quote:
Originally posted by HubbardRA
Kent, I don't go with compression release. I have been running a 243431 for years with the compression release bump filed off for over 15 years. It starts great with the standard S-G. I just have to keep a good belt and it has to be tight or it will slip. I also don't believe it is too much compression. I have also run engines with .060 shaved off the head. They still start fine. In fact, your finger should not be able to hold enough pressure to stop the engine from turning over if everything else if correct. I will go with a battery that is weak, or a bad starter solenoid. Low voltage causes the starter to pull more current and get very hot.
Same thing here, mine starts good with a good battery, but when it gets a little weak it will just kick back. It has really high compression. I will say bad battery or bad connection.
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Hi, II would look at the flywheel. Do the magnets look as if something has been rubbing. If so check the main brgs for slack. May be that when the piston is coming up against compression the belt pulls harder against the pulley and the play in the flywheel allows it to hit the ignition module. We have a similar problem with a Briggs with the ball bearings really loose years ago. The starter will get hot if it is stalled. Check the voltage at the starter when cranking It should be up around 10 volts. If not work backwards to find the drop. You didn't say if it is a mechnaical lock or just a stalles the starter. Is it a SG or a gear drive starter? Al Eden
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This eng is ''newer'' 10 hp vert with mini crank starter no belt type here .Starter was jumped with a running truck and good batt and STILL wont hump over compress srtoke,
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You have power to the starter, it would seem, with the jumping..Loose magnets in the starter? Or, Mick has a good point, the plug being too long is unlikely, though, as old model Briggs plugs are not directly over the piston. Worn out exhaust lobe on the cam or too great a gap in the exhaust valve, which is unusual, but possible.
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quote:
Originally posted by dlcentral
.Starter was jumped with a running truck and good batt and STILL wont hump over compress srtoke,
When you jumped it did you connect to the bat. w/ both cables or did you connect straight to the engine block w/ the ground and to the starter post w/ the possitive? If so, I don't care if the starter was changed, it's bad. If you went to the batt. w/ the leads then fix the ground cable on the engine block. BTW Kent, I think the decompresion bump is on the intake lobe.
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OK Rod brought up a point that I didn't catch or didn't pay attention to "You can stop it by holding your thumb over the plug hole. When the head was removed did you wiggle(rock) the crank back and forth and feel for play in the rod?, Could be hitting the case inside under compression if the rod is loose. Are the belts off the pulleys, I've seen rusty pullies that hold onto the belts to hard if it has set for a while.
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Does the engine turn over the full 360 degrees, or does it just turn about all the way and bind up. If so I would say a really bad sticking valve or loose connecting rod.
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