Hard turning 12 hp briggs

[temichels]

Hello, its been awhile since I have been on simple tractors, i have missed the pictures, but not the problems I always seem to goto u guys to help me with.... Well here it is...my 12 hp b & S is way to hard turning over...at first I thought might be s/g had it check at my local professional electrician...he shows it to be in wonderful condition...so I went to my ignition replaced it and all other associated wiring, still not the problem. I will start when jumped by my truck (running only) and when it runs it seems to run good. Does anyone have any ideas what other things could cause this. Its a 300421 type 0127, it doesn't appear to have any decompression machanism, and the valves and timing seem ok based on how it runs....I figured I would ask you guys before I get to the point of pulling the rest of my hair out. Thanks Tim

[UCD]

If it turns ok by jumping it could mean a weak battery. Also could be dirty electrical connections. Could be solenoid not making good internal contact. (dirty/bad contacts high resistance) Could also be a bad starter. 1) Clean all battery connections and all connections to solenoid and stater. 2) Have battery load tested. 3) Take starter to a Starter shop and have it tested on a growler for high current draw. 4) Replace solenoid.

[Unkle Spike]

I had one like this, and the brush wires were burned out and frayed in the starter. On the standard 12HP Briggs starter, you can buy the end cap with the brushes, that is the end opposite of the gear. They come with two wires inserted to hold the 4 brushes back. You just remove the two long through bolts, stick the new end cap on aligning where the cable attaches, and pull the retaining wires out. This is about the only thing that could be wrong with the starter, unless the windings are completely shot, which would be rare in my opinion. As UCD said, if you can find a real starter/generator shop, they can growler test and give you an idea of the current draw and a real good diagnosis. Actually I would follow UCD's advice first, then look to my shade tree ideas.

[temichels]

Hello again, I did take the s/g to a real shop they did put it on the growler, and found it to be in excellent shape. The engine is tight by hand, but does run halfway decent when I do jump it. I was curious if a bent valve was possible, or something else internally. obviously it would have to be a minor bend in order for it to run. But I am at a loss cause the s/g turns out to be okey dokey. It doesn't have a solenoid, igniting switch to regulator to s/g. I have replaced all wiring with the exception of the mag. Is there something simple i can do to determine internal problems? Thanks Tim

[UCD]

NO Solenoid? What tractor is this in? A solenoid is needed to get enough current to the starter to turn it. Are you back feeding the generator part turning it into a motor to turn the engine? There are two sides to a Starter Gen. Starter circuit and Generator circuit.

[tec2484]

You say its tight by hand, How far have you turned it by hand? 1/2 turn 2 turns? Hows the oil level? Over full could end up on the rings and make a very good seal. Low oil level could have galled up a bearing. Does it smoke when running? I have a briggs 14hp ic that runs ok for a few min then starts smoking worse the longer you run it after 20 min if you shut it off you play heck restarting it for a day or so. needs rings BAD!

[Unkle Spike]

I had another thought, see how hard it cranks with the spark plug out, the engine should turn relativley free with the plug out, and you can turn it by hand and see if there are any "tight" spots in the rotation which could help diagnose problems there.