Motorcycle Repair: 83 RX50, two stroke engines, yamaha rx50

Question
I just got a Yamaha RX50 with 810 miles on it.  It has been sitting for a couple of years.  I cleaned the carb and was able to get it started but it will only run for a few seconds then quit.  I'm not sure if this is a carburation problem or not.  I've been told that it might be the oil pump but I'm not sure how to check it.  If it is the oil pump can I just add oil to the gas?  At this point I want to spend as little as possible to get it running while I make appearence modifications.  I traded a gallon of auto paint for it.

I don't have any experience with two stroke engines so any help would be appreciated.

Thank you for your time.

Roy Rickert  

Answer
Roy,
 There can be any number of things leading to the problem.  If we were to go right to the most plausable ailment I woud say it is very possible you have a malfuntioning carburator. You may have contaminants and/or varnish on critical parts. It is also possible your choke is malfuntioning, make sure you are indeed opening the choke after the engine warms up. Here is some guidance on cleaning carbs I've given others:

Disassemble, clean all jets and orifaces with solvent and COMPRESSED AIR ONLY, use NO wire or picks to clean holes/airways. Rebuild carbs with new gaskets and make sure your floats are set correctly. . Do not overlook the float level, be very sure you are not starving for fuel. In relation make sure fuel flow is unobstructed and use a good in-line fuel filter from the tank to the carb. Even tiny particles in the fuel can get logged in critical areas and cause havoc. Floats are suppossed to push the valve up into it's seat when they rise from the fuel. Sometimes they get debris around them or varnish up with old dried fuel and get stuck either open or closed.
Don't go right into assuming the oil pump is to blame.  Lack of oil can be very detrimental however pumps are rarely to blame.  If later you are worried if you are getting oil though the pump you can run w/ some temp. premix and take the hose off the carb while running and see if oil is pumping out.  Be aware that the oil delivery is VERY slow, this is normal.  If all is ok, replace tank w/ staight fuel and be sure oil tank is full.

Hope this helps,
mike