I'd throw an aluminum bulkhead on it for piece of mind and a tad more weight up front. Big Bore or Proline shocks are great upgrades too. Tires? No such thing as too many.:) Aluminum carriers to go with the knuckles wouldn't be a bad idea either.
Yes but you'll probably just blow the rearend off of it and ruin a jem. If you go through with it, just make sure to get a motor with the propper size shaft.
There's a great sticky at the top of the nitro forum. The metal flakes are probably from the sleeve. May indicate some abuse or just a lot of fuel run through the engine.
I run 12t Titians on 14.4 volts. Have been for a few years. Geared properly of coarse. Gearing and/or a worn out motor was the cause of death. Thunder Tiger makes a 15t 550 that would be a little more forgiving when it comes to gearing. You will always have to gear down when running on grass if...
If you sucked sand into the engine, it's most likely destroyed. You may have been able to tare it a part and clean it right after the first stall. But by flushing it and turning it over with sand in it, you only finished the destruction. Tare it a part and observe the carnage. I bet you'll find...
5.9's are hit and miss. Lots of fuel consumption while making little power. Piccos are good engines. No reason to drop f bombs either bro. Women and children hangout here.
You have a big leak somewhere. Check the pipe to header coupler, header gasket, fuel tank seal... All the easy to get at places first. If all that checks out, I'd seal the entire engine and try again.
Lean it a hair on both needles and preheat it with a hair dryer or heat gun. New engines are tight. The heat expands the internals, allowing the engine to spin and start easier.