Motorcycle Repair: starting issues, vacuum problem, starter fluid

Question
Hi there.  First, I really appreciate any advice you can give me -- this is a great site!  Second, I know you are a Honda expert, and I have a Yamaha, but I think this is general enough that you could help me out.  So, I recently bought this 1982 yamaha.  The problem is that it won't fire up cold unless I use starter fluid.  It will certainly crank, so I think the starter and battery are fine.  When I bought it the guy didn't know much about this bike, and had the fuelcock set to 'prime'.  I'm afraid this flooded the carbs.  But I have fired it up since then.  Do you think the carbs need to be cleaned?  I was also thinking it could be a vacuum problem, as it is an old bike.  Again, thanks for any help you can give.

Answer
Steven, it could be a couple of reasons.  The engine may not be getting any fuel so the petcock or carbs may need cleaning or repair.  The other cause could be low compression.  Ether has a very low ignition point and it will ignite easily and once the engine is running the cylinder can generate enough compression to stay running.  If the bike has good compression with a compression check, it probably a carb problem.

Regards
Rich