Hi all I am still having trouble with my 1977 XS250 starting. The bike is a standard 250 with matching engine and frame numbers but has 400 barrels and head, the carbs are standard 250.  First of all I was convinced it was the carbs but after exhaustive work on them and speaking to other people I am now not so sure. My last efforts were to remove the starter motor and have it checked, that was ok. Then someone who used to own one and had done the same 400 top end swap suggested changing the condenser(s). I done this Saturday and still no joy. Any theories would be welcome as I am running out of ideas. 

Hi I am new to the forum but have you checked you are getting a spark at the plugs? Is the engine firing or not?

Hi yes I have a spark at the plugs and the bike will eventually run. It just takes so long to start, so long that you would drain the battery before it started. Once running it is not too bad but even when warm if you turn it off it is very difficult to restart.

DO a compression test ,   3 things needed to start. Spark/fuel [ you have both]  and GOOD  compression,,

Yes I have done a compression test and it was really good.

is it gapped right,  plugs and points. clean air filter, make sure you have good fuel feed too.

Edited August 31, 20159 yr by up.yours

Its an xs250, they do that...Burn it

Knowing my luck the fire would go out !

Look on the bright side, its better than a Z250.........um!