Hey everyone! I'm new here and could really use some help and advice. I recently got an 07 750 Brute Force from a Neighbor. He got it brand new, drove it like three times, then let it sit for too long. He then took the carbs off to get it running again and ended up letting it sit outside like that for several years with carbs, seat, and plastics off. The engine was full of water and is totally seized. I went thru the usual process to free it up and ended up removing the heads and hitting the rear piston with a wood block. The engine now turns but only the front piston moves, rear is still seized. I think the engine is junk at this point. I think everything besides the engine should be fine on this thing. It probably has under a hundred hours, easy. I wonder about the other stuff, especially the electronics from sitting outside uncovered for so long. Should I try to buy a wrecked 750 Brute Force and swap the engine to this one? Should I buy one that runs for a few thousand and keep this one for parts? Could I get a 650 for cheaper and swap that engine in or keep this for parts for it. I have no idea what parts are interchangeable from the 650. l I have a shop and tools and capability, but not sure what the most cost and time effective approach would be. Any feedback would be greatly appreciated!

 

If the rear piston is stuck and won't free, then the only bit of the engine that is "junk" is the rear piston. However, the problem is getting it out without wrecking the engine. Worst case is to cut it up in the bore so you can lift cylinder off. Assuming the "fill cylinder with diesel or Acetone/ATF mixture for a week" didn't work, I would try getting the piston very hot and letting it cool, the expansion when hot may just compress it enough to free when cool. If that doesn't work, cut it, using a blowtorch. However this will leave bits in the bottom end, so a complete strip and rebuild would be needed to get them out.

Electrics may have suffered, but it is surprising how often they work OK once dried out. Switches are the most likely to give trouble, so suspect them first if something doesn't work.

 

Thanks for the input. Since the engine was full of water and the front piston moves while rotating the crank but the rear does not, that means that somehow the rear piston/rod is not connected to the crankshaft anymore. My thought is that the rod bolts were rusted and snapped while I was trying to free it up. I doubt the wrist pin, rod, or crank would've broken. Usually rod bolts are the weak point. This means I have to get access to the bottom end, and it also means that there has to be pretty severe rust in the bottom end. I can't imagine something breaking in the bottom end without rust weakening it just by me turning the engine by hand. I guess I could unbolt the rear jug and see what comes out. Let me know if I'm missing something here. I have no experience with these engines. Thanks!

 

I have no experience with them either, farmers in the UK don't usually go for anything bigger than 500cc with petrol prices at £1.42 a litre (circa $8 a gallon). Anyway, it is worth taking the rear cylinder off and looking. You could then get the rear piston out on a press, if the bottom end is salvageable.