mine starts fine lots of comp. but when warm bogs out and gas runs out carb and exhaust and backfires bad was told it was crank seals how hard are they to replace and where can i find a schematic drawing to do this thanks ont the motor the plate says capac 299ccm is it a 250 or 300 bore is76mm stroke is 66mm

Looks like someone has put an Olympique 300 engine in there because the Elan did not come out with that size in a single cylinder. You will have to split the crankcase to change the seals. However I don't understand how bad seals could cause gas to run out of the carb and exhaust. Have you checked out the carb for problems. If it is a stock carburetor it should be a Tillotson HR diaphragm type.

Probaly not carb seals, sounds more like condenser, clean points, or if pitted replace, and definitely replace condenser.

Sounds to me that you have air leaking that gets worse when the motor gets warm, i.e. gaskets, seals, air/fuel lines, etc.

umm just rebuilt a twin elan 250 and we had problems with the carb having its diaphrams in the carbs built in pump bing in wron and the little needle inside the top of the pump getting stuck. this caused it to piss fuel out the carb and out the breather port. also flooded the thing and it would run till warm then wouldn't start. not sure on what motor u have or if it even has the same carb setup. if so clean it out fully and remember how to put the diaphrams back in properly. they can cause hell. good luck sweet little sled by the way