Starting and Stalling - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
 
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post #1 of 2 (permalink) Old 01-19-2006, 09:41 PM Thread Starter
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Starting and Stalling

Also See Hot Starting Problem
Also See Vapor Lock

STARTING PROCEDURE FOR YOUR VN750 (assuming you are serious and already have a MF battery):

COLD STARTING Advance choke to 1/2. Crank engine. Whens she fires, go immediately to full choke. Thence decrease choke gradually as the engine warms and races until the choke is off and she idles normally.

HOT STARTING Crank engine while rolling moderately on throttle. She should instantly roar to life. Nevcer use the choke in these circumstances.

RELATED ISSUE I believe the lean factory setting on the idle airscrews works against easy starting. Everyone with starting issues should consider doing the simple and well-document mod of backing these 2 screws out a little. -Gary @ Penn State


The VN750 can be a cold-blooded beast. If I don't run mine every day, it gets difficult to start. I find that if I fully choke it, then release the choke about 5-10 degrees, it starts much easier. It's an art that you'll soon pick up...

You need three things for your bike to run. Air, fuel and spark. No air is usually the last to check since not much can go wrong there.

Check fuel: How old is the gas in the tank? Have you been using Seafoam or something simular to keep your fuel fresh? After you crank the engine pull your plugs and see if they are wet. Wet plugs means you have fuel going to the cylinder. The fuel may not burn if it's not good though.

Check for spark: Gap your plugs! Remove a plug and put the wire back on. Hold the end of the plug to ground with something insulated, crank the engine and see if you have spark at the plug. Do this to all the plugs.
Once you figure out which of the three you don't have it's easier to track down the problem from there. Hope this helps.


Well, Pete, first of all you need a modern, well-charged battery as agreed upon by almost everyone. Next, the choke technique may vary from bike to bike, but some of us have starting problems with full choke (no start, engine floods, backfires). On my 2004 VN750 the engine will fire without choke, but won't sustain without it.

Solution: set the choke to 1/2, crank the engine, and immediately go to full choke when she fires. It may take 2 or 3 tries but it always works for me. I then hang around while she warms up and I decrease the choke when the engine races until she idles without choke and is ready to go. I wouldn't dare ride before the engine is warm in cold weather, like everyone does with their cages (bad for the engine and likely to stall when you stop). The above choke technique worked on Thursday in below-freezing temperatures, but I'm not sure I want to try it below zero. Incidentally, some of our bikes also have a hot-restart problem that has no such simple solution as far as I know.

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Try cranking a few revs at full choke or until she backfires. Then wait a half-minute, set the choke at 1/2, and crank her while your left hand is on the choke until she fires (no throttle). The instant she fires, advance the choke to full. If this fails, try again. This method works for me even in sub-freezing temperatures, and several other group members use it as well. If it doesn't work for you, then there may be some other problem going on. -Gary @ Penn State
If you let out the clutch and it dies, sounds like the kickstand switch. Sometimes it gets "gummed up" I guess. Try it with your finger and see if it's a little sticky, then give it a nice bath in WD-40 and see if that fixes it. If it dies just from putting it in gear when you have the clutch lever pulled in, then that's a different problem and I don't know what to tell you. Also, just for good measure, squirt a little WD-40 into the keyhole. Sometimes that fixes the sputtering while riding syndrome

Yep. sounds like the kickstand switch. Someone else reported this same problem and it turned out to be water in the switch and/or wiring.

This may sound crazy, but it is true. I was having similar problems and Gypsy suggested that the extra keys hanging from my key chain were contacting the frame and causing an elecrtical 'short' to ground throught the keys and the key ring. I removed the extra keys, leaving only the ignition key, and the problem stopped. Some VN 750s throughout its existance have had defective ignition switches. For instance, with my 1995 VN 750, the engine would die if I turned the handlebars hard right. One time I turned the handlebars hard left and the main 30 amp fuse operated (blew). I replaced the ignition switch, and that problem was solved. It can be repaired though, but I happened to have an extra one. The sources of these electrical problems are very hard to find sometimes. I guess the only way is by progress of elimination and determination. Any of the other replys to your post could be the cause too, so don't overlook anything.

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I had a similar problem, and it was definately related to the ignition switch. In my case, it might have been not having the key fully turned (and locked in) on the proper position. WD-40 in the key hole, and some repetitive manipulation thruogh the key positions, and the problem went away. Good luck.
...in the dark, see if there is any arcing around the plugs, caps, wires etc. Mine ran ****ty sometimes until I looked at the @ 1 cyl.....better that the 4th of July in there...

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Did you clean out the carbs and fuel lines..? Buy a can of gumout and spray out all the fuel lines and tubes and carbs...Sorry..is hard to give a diagnosis online...how old is the bike..( rust in tank...petcock filter cloggged) are there pinched wires?...what did those plugs look like?....yes alot of questions...alot of possibilities... The fact that it comes and goes sounds like an electrical problem...bad coil...shorting wire...etc...but an improper running carb can be possible too...wouldn't just junk the thing because you haven't figured out what is wrong yet....So a trip to the shop may be a good idea if you are unable to fix/find the cause of the problem. Sorry could not be of more help.. Knifemaker
May not be the same problem but right after I bought my bike, I too noticed that it was running on only one cylinder (front cylinder was not firing) and would die on me occasionally as you describe. Had the crabs rebuilt and that seemed to fix the problem. When I bought the bike, it had been sitting in a garage with very little use for several years. I took it to the dealer and the wrench was able to tell by the smell of the gas that it was old and suggested that the crabs most likely had gunk build up inside them. I wonder if he was high on something else but anyway. I had even filled the tank with fresh gas since buying the bike and he claimed he could still tell that it was bad. I suppose someone who works on gas engines a lot would know the smell of bad gas vs. good gas.

I have also experienced the acceleration problems that are caused by the breather hose bottoming out as Preach mentioned in his post. Behind the right ear, there is a breather hose that fits into a channel of molded inside the ear cover. If that hose is pressed all the way into the channel so that the end butts up against the ear case, it will cause problems at higher Rams. The bike will sputter and choke as if it is running out of gas but it never died on me. This is an easy check and an easy fix (just slide the hose back a little so that the end is not butted up against the case) but your problem more closely resembles my original problem which I solved with a crab rebuild. I paid to have it done but that was before I joined this group or bought a Climber's manual. If I had to do it again, I might consider rebuilding them myself.

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It's been my experience that sometimes an electrical problem "seems" to be fuel flow problems. Please check your ground connections - the big one right by the battery, and the smaller one to your wiring harness. Also, check your connections to your coils. This has happened to me, twice it was the electrical ground, once it was an intake boot on the carb was gapped and sucking air. The electrical problem had me running rough at all rpms, the boot loose had a deadening effect at highway cruise - flat throttle and no response to more gas. Rick B. VN700 A1 stock
Some background - I've got an '04 VN750 and had the battery die on me 3 times! The first time, I thought the dealership hadn't charged the battery enough, but I figured, what the heck, I was getting a MF one anyways. The 2nd & 3rd time were a big annoyance, but I thought it was just letting my bike sit for a couple of weeks without riding. I did the voltage checks...wouldn't get 13-14 volts until about 3000RPM...checked stator resistance and found that my stator was BAD! I was really freaking out 'cause I knew this required an engine pull to fix (even though it would have been covered by warranty). Anyways, before I took it to the dealership, I did more research (thanks for everyones help in this forum), and I read in the Files section that someone's fuse on one of the stator wires had blown, and the voltage had dropped considerably...so I checked the factory wires (not fused)...and one of the stator wire connectors had come loose! First problem solved! Now it's time for preventative maintenance.

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My bike was starting like the battery was dying. I added a extra ground wire from the battery to the top air filter mounting cap screw. It solved the problem. Mike '89 vn 750

Last edited by Vulcan Verses; 01-19-2006 at 09:51 PM.
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post #2 of 2 (permalink) Old 01-19-2006, 09:43 PM Thread Starter
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Sick Scoot
I jumped on my bike today for a quick spin, and it ran terrible. It would die every time I let off, and would only start with full choke. I figured it was in my fuel switch (which has been flakey), so I rebuilt it with a new kit. Still it ran terrible, and backfired big time. I tried adjusting the air fuel mixture and discovered that the front cyl carb was non responsive. I could turn the screw all the way in and the bike still ran the same. So, now I am thinking I have an air leak in that carb. I checked the diaphram and it seems to be ok. I guess I will take the carb off and see if I can find a leak. Interestingly, the idle stays around 3K for a long time after I close the throttle. I think I have reached the limit of my vast expertise (make that half-vast experience). May have to call in the experts.
Is it leaking amy gas from around the petcock? I had similar symptoms last summer. I was able to goose it over to the shop, and he said that both carb holders (the rubber thingies that attach the carbs to the cylinders) had leaks, and the diapragm in the petcock was blown. He replaced both holders and rebuilt the pectock - fixed it right up! The idle staying up when you back off the throttle could be caused by leaks in the carb holders, I think. Try spraying WD40 on them while the bike is running - if the idle picks up, you have a leak. Luckily those rubber carb holders are not too expensive (around $22, IIRC). Jim "Pick" Foster Dixon, IL VROC #9492, TNVROC #0020 H.M. 1986 VN750 "Babe", 1982 KZ440 LTD

Have you tried replacing a battery, it may crank, but it may not be all the way charged. I had the same problem on mine, I charged the battery and all was solved. (still can't explain it!)

Check the basics: fuel shutoff valve? My 2000 when cold likes full choke, and don't touch the throttle, or it'll die. Re-adjust the choke to keep rpm below 2000 until it gets warmed up some - maybe a minute or more. Backing out the carb mixture screws helped this hard starting - have you ever done that?

Do you have the stock battery? If so, check water levels and for tight connections. If a sealed Westco or Yuasa, check connections only. If you have a volt meter, check the battery voltage prior to doing anything. Should be 12+ or you have a bad battery, right?

Speaking of fuel shutoff valve.. How about bad gas? Some of the newer additives that they are putting in gas seem to break the gas down faster and they don't vaporize well. If it still won't start or stay running try draining the carb bowls, see what comes out of them. Bad gas will look milky or crudy. Are you a seafoam convert yet?

First off...you should not be running premium fuel..it can actualy damage your engine. Do you ever use Seafaom?..Make sure the boots holding the carbs are tight and the ones from your airbox. ( make sure the cable linkage is working right also) Buy some gumout in the spray can and blow it through all the carb tubes..Check your plugs...try that and see what happens........

I have also experienced the acceleration problems that are caused by the breather hose bottoming out as Preach mentioned in his post. Behind the right ear, there is a breather hose that fits into a channel of molded inside the ear cover. If that hose is pressed all the way into the channel so that the end butts up against the ear case, it will cause problems at higher Rams. The bike will sputter and choke as if it is running out of gas but it never died on me. This is an easy check and an easy fix (just slide the hose back a little so that the end is not butted up against the case) but your problem more closely resembles my original problem which I solved with a crab rebuild. I paid to have it done but that was before I joined this group or bought a Climber's manual. If I had to do it again, I might consider rebuilding them myself.

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Q: II have a new Vulcan 750. It seems like there is excessive play in the drivetrain. It feels like the damper pad in the rear drum is missing. It is most noticable in first and second gear. Does anyone else feel this jerkiness (or is it just me)?
A: Two things come to mind...actually, three.

1. The vent hose fromt the tee over the carbs to the back of the right ear (air filter housing) may be bottoming out. Pull it back slightly; better yet, cut it off at a 45 angle, so it can't shut off the vent.

2. The tank vent under the cap may be closing off, or the tank vent tube is stopping up. The vent in the cap itself is very tiny, and it doesn't take much. BTW, that tiny vent benefits from being drilled out with the next size up wire guage bit. Take the cap apart before you drill it, tho! ;-)

3. The most likely one--trash in the carb needle seats. Take the drain plug out of the bottom of each carb and let the fuel drain out, then use the little red spray tube with a can of Gumout to load the float bowl with it, holding a finger over the drain plug hole, and spraying up thru the drain hole. Flood the float bowl with the Gumout, then remove the spray tube and your finger. Couple of times with each carb oughta do it. It's easier to tell when the bowl is flooded if you pull the vent hose out of the right ear and let it dangle out the side; Gumout will come out the tube when it's full. Replace the drain plug, leaving it slightly open, put the vent tube back in the right ear, put the tank back on, turn the petcock to Off 'til fuel starts coming out the drain, and close the drain plugs. Turn the petcock on, fire up the bike, and see how she runs then. hth Jim

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Q: Starting problem Went to start my bike this a.m. Turned the key to "on," had lights and all, hit the start button, and it made this sorta clicking sound from under the seat. No sound of the engine trying to fire at all. No problems prior to this. Coulda got a little damp in my garage yesterday as it was close to the door, the door was open and we had storms yesterday. What up with this? TIA Stewart
A: the battery is probably dead, try charging it, then check the charging system after you get it to crank. that buzzing is the start solenoid engaging, then disengaging when the starter pulls the voltage too low for the coil to stay magnetized, then it repeats. Thanks, just my 2 cents....... Beavis

A: The noise is the starter relay (aka solenoid) which is located behind the right side cover. The reason that it is making noise is low voltage - check the fluid level in the battery (it should be between the lines on the side of the battery - use water [preferably distilled water] to bring it to the line). If the fluid is OK, charge the battery.

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Q: I charged the battery overnight. I cleaned the terminals/connections. Still just clicking when I try to start. Now what? Time for a new battery? This one, I believe, is two years old, max.
A: I'd take the battery to a shop that carries my favorite flavor of battery and have it load tested. Most likely it's shot. Get a new battery and away you go. If the battery tests ok, you have more detective work to do.

A: Hook it up to your car battery as if you were to jump start it. But do not start up the car. This will help rule out the battery if it still won't start. Ken
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