Motorcycle Repair: kawasaki 750 vulcan, kawasaki vulcan 750, gasoline additives

Question
i bought a kawasaki vulcan 750 with about 3500 miles on it, i now have 5000 miles on it, from time to time when i start it, it cranks and backfires, i stop wait a few seconds and try again, when it starts it runs fine, i have replaced the battery and made sure the posts are tight, replaced the spark plugs, but it still does it but not always, sometimes it seems to crank like the battery is weak and sometimes it sounds likes the battery is fine, i followed the hot wire from the battery to whatever it goes to and its tight same with negative side, can you help me
bill

Answer
Hi Bill,

If the battery is fully charged and in good condition, I suspect one of the following:

Corroded or burned starter button contacts.
Corroded or burned starter solenoid contacts.
Water shorting due to washing or rain.
Defective ignition switch or CDI.
Carburetor problems.

I would need you to perform tests and relay test results for diagnosis.

Things I need to know:

1. Describe the appearance of the old and new spark plugs to me. Remember and advise which cylinder each plug is removed from.
2. Recent repairs, service, or modifications.
3. Was the Vulcan stored or non-started for any periods?
4. What is battery voltage with engine off, at idle, and above 3k rpm?
5. What is cylinder compression?
6. Any gasoline additives used?
7. Any other info is helpful.

Get a copy of the service/repair manual. They cost about $25 on average. Find manuals at "www.bikebandit.com" or "www.eBay.com"

The manual has illustrated test and troubleshooting information. It will pay for itself with the first repair you perform.

Visit: "www.dansmc.com" This is a free MC repair course on-line.

I return tech information files by email. There was no email address with your question as requested.

Respectfully,
Mark Shively