Hot starting problem - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
 
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post #1 of 1 (permalink) Old 01-19-2006, 09:46 PM Thread Starter
Vulcan Verses
 
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Hot starting problem

Also see Starting and Stalling
Also See Vapor Lock

Quote:
Problem: I am having the problem with my Vulcan 750 sometimes either backfiring or not starting at all when trying to start the bike with a warm engine (but other times it starts up fine – it is very sporadic). It has been doing this ever since I bought the bike a year ago. I have taken the bike into the Kawasaki dealer, but they say that they can't fix the problem until they actually see the problem for themselves first hand, and, of course, every time they try to start it up with a warm engine, it starts just fine.
A: Just wanted to tell ya'll that this board helped solve my "won't start when hot" VN 750 bike and I wanted to give a Big Thanks. My '05 Vulcan 750 would only crank and backfire when hot unless I waited 15-20 minutes. I put in a new MF battery and cleaned all ground connections. Didn't help. So I did the "pickup coil mod" outlined in the Files and Presto-chango, it starts everytime when hot with just a touch of the starter. Couldn't be more pleased with the info presented! For general information, the gap was approx .035", so I used my Dremel tool, some Locktite, and adjusted it so the gap is now at .020". If anyone is having this same problem, I say "do it". The job is much easier than it sounds. Again THANKS.


A: Ryan, I'm not sure a mechanic is going to fix this for you. It's an indemic problem with the VN750 that many of us have, including me. If I park the bike hot and come back in 5 minutes, it won't start. After it cools off, say 15-20 mins., it will start with no choke and part throttle. Popular logic says this stems from the regulator/rectifier, that sits under the battery and gets hot from the exhaust pipes when the bike is not moving. If so, a simple modification by you or a mechanic will solve the problem by relocating the R/R. Others have seen the problem disappear after they replaced the stock battery with a modern sealed WestCo or Yuasa battery, very important for everyone but it didn't solve this particular problem for me. I hope to get to the bottom of the problem this season, but in the meantime I just avoid ever having to do a hot restart (for example, fill up with gas from a can at home when the bike is cold, rather than at a gas station). I hope this helps, and please stay tuned.

FWIW, I did have this hot starting problem once and it went away with a new set of plugs. May not be the real fix, but a cheap thing to try.
________

Quote:
Q: I'm low on gas, but not on reserve or anything, and my bike starts coughing and dies.
A: This sounds like a blocked gas cap vent. Partial vacuum in the tank. If this happens again, you might try simply opening the cap, closing it again and see if she starts up.

A: I noticed the same problem with my bike for awhile. Usualy I thought it was running out of gas..so I switched to reserve...but then it conked out..was able to start it in a few minutes. I think what was happening was either there was goo in the reserve tube, or perhaps just air?...OR..I think that when I hit the reserve the float bowl was almost empty...and it took some time for it to refil after I made the switch. Not really sure...but now I always try to keep gas in the bike...and I use Seafoam to clean out possible goo....so far this seems to have solved the problem...although I haven't let the fuel level go that far down again.

Quote:
Q: I bought an 87 Vulcan with 6000 miles on it last November. It was sitting in the garage all winter long. In the past three weeks I changed the air filters, hooked up the choke cable, adjusted the spark plugs, bought and charged up the new battery. When I push the starter button it keeps trying but hardly ever gets it going. Then it runs for about 5 seconds under 1000RPM an then dies. I tried to start it today but I quit after I heard two "gunshots" coming from the exhaust. What do you guys think I should try or adjust? I have no idea when was the last time this bike was actually running. Thanks for your help.
A: Ah !!! Sounds like sour gas, i would drain all gas. put in new plugs too. and drain the carbs too...i think u might just be aok then !! this has woked for me many,many times thru the years. good luck !!

A: I had the same problem all winter. I would go to start it every two weeks and it was one gunshot after another. I had good gas with Stabil in it so I knew it wasn't that. I held the throttle open all the way to introduce as much air as possible and that helped. The battery died almost every time though. I finally got a maintenance free Yuasa battery and charged it up as per the instructions. That baby cranks over like a dream every time. It never takes more than two coughs before she starts purring. I'd like to apologize in advance to the fine ladies of this group for speaking of my machine in a female tense. No disrespect intended. If you didn't get a maintenance free battery, you may still have problems. I hate batteries with water in them. Send the water to Poland Spring and make mine maintenance free...lol.

Quote:
Q: My poor baby has been doing great. I just now went to the store, came out and she started fine. Drove about 20 feet and then the entire electrical system was gone, no power at all, no lights of any kind I took the seat off and looked at the battery and it seemed fine, at least the conections were there, I don't know where the fuses are. Is there a main kinda fuse that could account for this? I wiggeled the key, took it in and out but no go.. Any ideas would help..
A: Check the 30 amp main fuze.

Well if you followed my previous posts you may remember that I had some trouble with the electrical system charging adequately lately. Well after testing the stator, the starter, the fuse box, the R/R. The next thing to check since the bike at one point would not even engage the starter, was to check the starter solenoid. Yep, the solenoid must have been bad. I jumped across the contacts with a screw driver and the bike started right up. Went to the local shop/salvage and dug up a sort a kinda close to the oem solenoid. Installed it and presto, I was back on the road. I was still worried that none of the electric readings I was getting from various volt meters were anything alike. I dropped by the local dealership and spoke the service manager who brought out his volt meter and load tester. He checked my systems and then the battery. Charge was fine and the battery past the load test with flying colors. I do have an 8 month old Yuasa MF battery. So my conclusion is that the starter solenoid was some how drawing current and killing the battery. I did notice that after replacing the solenoid, the bike seemed to start easier, like it was spinning the starter faster. So maybe the solenoid had been going bad for a while and not providing the starter the appropriate voltage needed, then finally shorted out.

Quote:
Q: Took a short ride today, hit a bad bump (almost got launched) and all of a sudden engine stalled when I got to next stop light. Restarted ok, but had to use throttle to keep running, engine smelled rich, ran ok at rpms, just difficult to keep at idle. Also stumbling a bit off the line, but again ok once rpms are up above 2000. Any ideas?? All responses greatly appreciated....Tom
A: You`ve hit the nail squarely on the head Tom. This happens to mine from time to time. This IS a short term cure, and it WORKS. Turn OFF the petcock whilst the engine is running. Rev if necessary to keep it going. Once the extra fuel is burnt, and she is idling OK, turn the petcock ON again. Now its down to you to keep an eye on yer fuel guage. Dont go into reserve...and DONT turn off the petcock. Its vaccuum fed, so you will not lose fuel whilst standing. I had the tank and carbs stripped down and cleaned when this first happened to me...but it still did it again. Dunno why, but might be a week diaphram. No probs now as I know how to get over it when it happens.
spock_gb

Last edited by Vulcan Verses; 01-19-2006 at 09:52 PM.
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