Perplexing Vulcan

I have a 2001 750 Vulcan. For the past month, it has been getting
more difficult to cold start. At full choke, no throttle, it used to
start easily. Now, at full choke no throttle it just backfires some.
If I go full choke hit the start button and immediately move the choke
lever to no choke, it has been starting....yet reluctantly and it
takes a couple of seconds for it to start to run adequetley.
Yesterday, it finally didn't start. Trying to start it, I ran the
battery pretty low. I left it for a couple of hours, came back, hit
the start button and it started right off.
When the weather gets cool, I've gotten into the habit of placing the
bike in the sun for a while and it seems to start better. I just
didn't do that yesterday. The temperature was in the low 60's so I
didn't think I needed to do that trick.
Once it does start and I run it, I have no problems at all with it.
It has about 14,000 miles. Does this sound like an ignition problem
or a carburetor problem? I'm wondering if the choke needs adjustment
but there doesn't seem to be a way to do that...there isn't even a
procedure for that in the service manual that I can find. I'm going
to put new plugs in it but I'm thinking that really isn't the problem.
I was hoping to get it to winter time without taking it in for a
tune-up. Maybe that just won't happen.
Any help would be appreciated.

 

Clean the carb completely, I'm assuming this is a CV and not fuel
injected. The choke is on a different circuit in the carb than the slow
jet or main pilot. Make sure all the passages are open. The choke has
tiny holes in front of the venture and butterfly. Make sure all pilots
are taken out and cleaned. If you don't know how or feel comfortable,
have it done or get a book and someone who has been through a cab
before. When taking out a pilot, make sure you count how many turns to
bottom it. Then take it out. When putting it back. Bottom it and back
it out the same amount of turns it took to bottom it the first time.
Make sure the float valve is opening and the bowl is filling properly.

After you clean each carb, synchronize them together.

Check the battery for proper voltage. Sometime the battery will have
enough amps to turn the engine, but not enough to start it.

If you are able, check the compression on each cylinder. Should be
between 100 psi to 200 psi. Each cylinder should be within 10% of each
other.

Temperature rarely effects spark plugs. They either work or they don't.
Before you put in new plugs, check the old ones by letting them hang
outside the cylinder and see if there is a blue/white spark that jumps
between the outside of the cylinder and the end of the plug. If it
does, it isn't your plugs.
If you put in new spark plugs, use a little anti-seize on the threads
and check for proper gap spacing.

Lastly, check for air leaks.

--
Page

'01 FXDWG, NTXNS
"Happy Hour" starts one twist of the throttle past neutral!
Remove the 123 to reply.

 

Before ripping the carbs out, or doing anything involving a lot of time,
see if you can try it with a new battery. I used to have a Magna that had
the same trouble, and I did all kinds of carb things, but once I resigned
myself to a new battery every two years the starting problems went away.

 

Sounds like you flooded it.
(Unless the weather got a lot warmer while it was sitting that is.)
Pragmatist

 

It's always the easiest things.....the battery was bad. Put a new
battery in and it starts and runs like it was new.
Thanks to everyone for your suggestions.