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Discussion Starter #1
I finally got my 1997 Vulcan 750 going, everything is pretty much done, including 4 new NGK spark plugs. It was running fine. I went for about a 60 mile ride, stopped at a fast food place, and when I started to leave, it would not start. It fired a couple of times, but that was it. I ran the new battery down. Finally a guy showed up with jumper cables, and I got it started after several minutes. I rode it back home, and it ran fine. I shut it down, and restarted it several times. Today I went to start it and ran into the same thing. It just would not start. I had jumper cables attached to it, so I had unlimited current. It just would not start. Plenty of spark, and the float bowls were full. I finally gave up. I only ran the starter for about 3 seconds at the time to avoid overheating it. Tried it with and without the choke. Nothing. I have had starting problems with Vulcan 750s before, and know it is a common problem. But I have never had one completely refuse to start after several minutes of firing. Cranking sounded normal. When it was running it idled fine and I hit 80 mph on the freeway with no problem. Very smooth, no misfiring. I have been starting and warming up the engine every couple of weeks since I bought it. It never refused to start. Any ideas?
 

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Discussion Starter #3
It did backfire a couple of times the first time, when I was 60 miles from home. Now it doesn't do anything, other than crank over. It does have spark. The entire evap and PAIR systems have been removed, and everything capped and plugged. Carb pilot screws have been turned out about 2 1/2 turns.
 

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NewB to Vulcans
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I have a theory about the ignition system being extremely voltage dependent, when the voltage at the electronics box drops the timing goes off. There is a wiring mod that changes how the ignition gets powered that seems to help those folks with recurring issues. Check the volts at the ignition box and the coils, it may give us a clue.
 

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Do your bike a favor, do the coil relay mod. that way you know your coils are getting 12 volts right off the battery. May not be the problem but it's one more thing that will help the over all health of your bike and you can rule out low voltage to the coils. I keep telling everyone once I did the coil mod it was like an instant fix, but we all have to learn at our own pace. I can't guarantee it will fix it but I know it won't hurt.
 

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Discussion Starter #6 (Edited)
Problem solved, I think. I replaced the new battery with another new battery. Now it starts fine (for a Vulcan 750) I believe the other battery was shorted internally. I discovered that when I disconnected the bike battery, and connected a car battery to the bike battery cables, it started right up, but would not start with the bike battery in place. I know it is charging, I'm getting 14.6-7V at 3000 RPM, which drops to 11.97V at idle with the headlight on high beam. I went through a stator replacement on my '02, so I know what to look for. I got the battery from Batteries Plus, and they exchanged it for free, even though they couldn't find anything wrong. Could have been intermittent. Electricity can do some strange things. I rode it almost 100 miles this morning, parked it in the garage, just went out and tried it, it started right up completely cold.

EDIT: I went out to the garage this morning when it was 37 degrees, the bike was completely cold, and it started right up. I will still consider doing that modification. I'm also going to get one of those little tiny jumpstart packs, and carry it with me on all my bikes when I ride them. I also keep all 6 of my bikes on battery maintainers. I switched from the Deltran Battery Tender Jr. to this one. https://www.autozone.com/test-scan-and-specialty-tools/battery-charger/duralast-2-amp-battery-charger-and-maintainer/613874_0_0?&searchText=dl2d After several years the Battery Tenders started failing, and the new ones are junk. The ones from Autozone put out 2 amps into a dead battery, then taper off, so they can be used as both a charger and maintainer.
 

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Hi all - I have an 86 Vulcan 750, 24,000 miles on her. This is the 2nd one I have owned, even same year and model. Bought my 1st one in 1990 as a 20 year old, and now at 50, I have had this one for 3 years. I have found this one is as finicky as the 1st one, lol. It runs good, but sometimes also starts hard, and backfires when starting it after its hot. I have read enough here to determine I surely need to change to an AGM battery, and the NGK Iridium plugs. Right now, it has the wet cell battery that the PO gave me with the bike, and the standard NGK plugs the manual calls for. Looking at a DEKA AGM battery. I am not home right now, to look, but I am pretty sure I should order the ETX15, however DEKA's website says it uses the ETX15L. The images of that "L" battery show the +\- sides of the battery opposite of what I seem to remember needing. The ETX15 images show the positive terminal on the right front of battery as installed. That's the battery I think I need, NOT the one suggested by DEKA. Any input on this thought before I drop the cash on a battery I cant use? Open to another brand if suggested also, this group has more knowledge than I do on this topic. Hoping to find right battery, install better plugs, and have that occasional fart\pop go away when hot starting. I guess I can take a look when I get home, thought I'd try here and order from work :) Thanks, Mike
 

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Hi all - I have an 86 Vulcan 750, 24,000 miles on her. This is the 2nd one I have owned, even same year and model. Bought my 1st one in 1990 as a 20 year old, and now at 50, I have had this one for 3 years. I have found this one is as finicky as the 1st one, lol. It runs good, but sometimes also starts hard, and backfires when starting it after its hot. I have read enough here to determine I surely need to change to an AGM battery, and the NGK Iridium plugs. Right now, it has the wet cell battery that the PO gave me with the bike, and the standard NGK plugs the manual calls for. Looking at a DEKO AGM battery. I am pretty sure I should order the ETX15, however DEKO's website says it uses the ETX15L. The images of that "L" battery show the +\- sides of the battery opposite of what I need. The ETX15 images show the positive terminal on the right front of battery as installed. That's the battery I think I need, NOT the one suggested by DEKO. Any input on this thought before I drop the cash on a battery I cant use? Open to another brand if suggested also, this group has more knowledge than I do on this topic. Hoping to find right battery, install better plugs, and have that occasional fart\pop go away when hot starting. Thanks, Mike
The hot start backfire is a sure sign of low cranking voltage on this bike. Do the AGM first.

If it's a Deka battery the "L" battery should be the right one, sometimes websites and pics aren't accurate. Could call them to verify.

I shop online for everything I can, but wanted the battery now, so I walked into Advance Auto. Been very happy with the Magnapower EXT15L (Deka cousin) I bought in Nov. 2013. It's now over 6 yrs old, not started since last summer, sat on the tender all winter until the tender died a month or so ago. Guess I'll soon see how it held up, hasn't failed so far.

Paid about $80 for the Magnapower back then, years later I bought a $38 AGM online to use on the atv. Going to find out how it's held up with very little running and no tender either, in unheated space. This $38 battery is a PowerStar from https://www.bigtimebattery.com/store/shotgun_motorcycle_batteries_1 year Warranty.html ... and it has started fine year after year.

Hot start
1) Get the AGM

2) Experiment with using the choke, especially after a run then stopping 5-10 minutes. I almost always pull the choke automatically, then if it doesn't fire right off, open the choke while continuing to crank. It's never flooded out and always starts. Goes against history and starting procedures but this bike has quirks.

3)Two Wire mod improves hot start
 

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The hot start backfire is a sure sign of low cranking voltage on this bike. Do the AGM first.

If it's a Deka battery the "L" battery should be the right one, sometimes websites and pics aren't accurate. Could call them to verify.

I shop online for everything I can, but wanted the battery now, so I walked into Advance Auto. Been very happy with the Magnapower EXT15L (Deka cousin) I bought in Nov. 2013. It's now over 6 yrs old, not started since last summer, sat on the tender all winter until the tender died a month or so ago. Guess I'll soon see how it held up, hasn't failed so far.


Hot start
1) Get the AGM

2) Experiment with using the choke, especially after a run then stopping 5-10 minutes. I almost always pull the choke automatically, then if it doesn't fire right off, open the choke while continuing to crank. It's never flooded out and always starts. Goes against history and starting procedures but this bike has quirks.

3)Two Wire mod improves hot start
Thanks, Spockster! I ordered the Deka "L" battery. Once I got home, I confirmed, and it was the correct one. I love the ride of the 86 Vulcan 750, that's why I bought this 2nd one when I had the chance. There is no question, though. They are one finicky bike! This one acts exactly like the one I had when I was 20. Of course, in 1990, AGM batteries were unheard of. I keep the battery on a tender through the winter in the garage, here in Maine. The bike fired right up, after a few short attempts. I don't like to over work the starter. I let it run for 20 minutes or so, and even ran it through a few gears, slowly, while on the center stand, to get the oil moving in the rear shaft, etc. Call me odd, but that's what I do once or twice through the winter. I do the same thing with my Jeep CJ. Start it up and get it warm, and Ride the brake, while just shifting the auto tranny through the gears to move the fluid around. Anyway, I have always found a new set of plugs to really make the bike run better. Previous owner had Champion plugs in it...JUNK! I changed them back to NGK when I got it, and it was a night and day difference in starting and running. Stock NGK's are cheap enough. I'm really leaning towards the iridium ones, but I will take your advice, and see how the battery itself works out first. It doesn't backfire when starting hot all the time, but boy, when it did, people hit the ground! lol. Embarrassing as hell! LOL I really don't think I have any fuel issues though, it does run and go like the wind. 24,000 miles is nothing for a a 34 year old bike.:smiley_th
 

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You're welcome. I did the same through winter with mine the first years, even got out to ride on the warmer days. Just haven't been able to keep up lately, so I'm going to see how this abuse affected the AGM at it's old age. The AGM is truly one of those improvements that pays off, didn't believe it until I lived it. Wet cells have been pitiful by comparison.

Have used a lot of spark plugs in a lot of engines, every description, even some with no side electrodes. Today, if they're not eroded away or caked up bad, I re-gap and re-use. Some engines even get worse MPG on platinum plugs. The bike still has the same Denso plugs that were in it when I bought it. When we ran leaded gas, plugs were worn to nubs in a year or two. Now they can last many tens of thousands of miles.

The backfire is embarrassing and scares the hell out of everyone at the gas pumps. Other times I'm willing to risk the backfire and it will often fire right up anyway. But for insurance, I pull the choke.

Always loved how this engine runs, it's a v-twin cruiser that revs and sounds like a sport bike, smooth as silk, and I like how it sounds with the earshave and stock pipes. My legs have always been too long for it, the seat needs to be slid back. My Yamaha 750 Special was a stretch limo compared to the Vulcan, but the V-twin would smoke the three cylinder.
 

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Well I finally got my Deka AGM battery Tuesday, Spockster. I tested it out of the box, and it showed 12.7V. I installed into bike, and hooked up my battery tender for 24 hours. Once unhooked, battery showed 13.3V. I turned the key on, and it did seem to start much better. That is especially true once the 2nd cylinder got fuel and helped balance the engine load, LOL. I let it idle for about 10 minutes. If it weren't so cold and rainy lately here I'd take her for a ride to see if performance is improved. One thing I have always noticed, which I think is normal, is at idle, when out of direct sunlight(Garage) I can see the green Neutral light oh so very lightly flickering. If I touch the throttle at all, and raise RPM's, it stops and stays solid. I believe it is a normal thing, and am not worried, as it will get better voltage driving than idling. Just thought it worth a mention. Cant wait to try it out on the road. Especially being stuck in the house so much during this quarantine crap. At least I have little things to tinker with that don't stop me from riding when opportunity comes. I have brake pads on the way for the front and rear. The front are low, but I have a few mm's left so I haven't run them too far. I'll change the rear when I get some sort of sign it's time, since 70+ percent of the braking is from the front. On another note I have to say this is a really great forum. The only way I could see it being better, was if it was a group of people hanging in a garage, with a keg in the corner, lol. That way, we could all meet, discuss, and even show one another what key things are, and how it all works, etc. Some brilliant advice here, and some of it I cant even wrap my head around just yet. I always have been mechanical. Electrical, I can deal with, but schematics get a bit complicated for me, unless I am just tracing a colored wire, etc. In real life, I have 32 years of producing acrylic sheet, aka Plexiglass. I am sure you have been seeing a lot of that lately! So, when it comes to plastic, I know most all, electrics, not so much, but always willing to try, but don't want to have to deal with this stator issue! Cheers to you, and the rest of this great forum! :smiley_th :smiley_th :smiley_th
 

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Yep, the AGM is a marvel of modern battery science.

Are you sure that's not the headlight warning light you're seeing? Think it's white though, but it sometimes does glow very dim. Otherwise maybe the neutral switch has gotten sticky or the green wire on it may be grounding slightly.

It's always a thing, when this bike sits a week or so, getting fuel into the one carb. A theory of mine is the angle of the carb, and sitting on the sidestand, gas evaporates out of it quicker. The carbs have the shared float chamber, then the chambers where the jets are, so I think maybe the rear cyl, carb dries out quicker.

Aren't you out of toilet paper and beer? You should ride on down to the local Piggly Wiggly and re-supply. Plenty of bikes out down here, rain for the next five days now.

Have had a real hankering for some draft beer lately, I need to go find a mini keg.
 

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Yep, the AGM is a marvel of modern battery science.

Are you sure that's not the headlight warning light you're seeing? Think it's white though, but it sometimes does glow very dim. Otherwise maybe the neutral switch has gotten sticky or the green wire on it may be grounding slightly.

It's always a thing, when this bike sits a week or so, getting fuel into the one carb. A theory of mine is the angle of the carb, and sitting on the sidestand, gas evaporates out of it quicker. The carbs have the shared float chamber, then the chambers where the jets are, so I think maybe the rear cyl, carb dries out quicker.

Aren't you out of toilet paper and beer? You should ride on down to the local Piggly Wiggly and re-supply. Plenty of bikes out down here, rain for the next five days now.

Have had a real hankering for some draft beer lately, I need to go find a mini keg.

HAHA - Plenty of toilet paper and beer! Tired of not being with buddies when drinking though. I seem to make no sense talking to myself after 6 or so beers, lol. I am sure it's the green neutral light. It's something only I would notice, I don't think it's an issue at all, it is SO slight. I agree on the carb issue. My old VN750 ran exactly the same way. You can hear a slight piston knock from rear cylinder, but only for a very short time. Once the fuel gets in there, the spark ignition is putting a lot more pressure on top of the piston to drive it back down. Not very loud at all, some people wouldn't even hear it, but I listen to my motor, lol. I tend to run a little seafoam in the tank throughout the summer, and always store it in winter with a heavy dose. The last thing I really want to waste time doing is removing and cleaning carbs. I'd rather do something more fun with it. However, we have had lower than normal temps for this time of year, and a lot of freakin rain. Enough to drive a person crazy. Grateful I have several cords of dry pine wood down back, a big ass bonfire pit, and a store with a beer cave 1 mile away. Beer and fire make me forget any worries at all, especially with good old Johnny Cash cranking from the truck. With enough beer, I can say I think I sing right on the note, lmao! :grin2::grin2:
 

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The light might clear up after a decent ride.

I always use seafoam at least once per season and in winter. I just measure it according to the directions. Actually cleaned out a pilot jet while riding by having seafoam in it for storage. Lots of slowing down and taking off, using the choke, about 25 miles and it was cleaned out.

Mild winter down here, almost no snow at all and not much colder than teens for one night at a time. Plenty of 40°-60° nights/days.

Bread, that's it, bread, you need to ride to the store for bread, or just some Goody's powder.
 

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The light might clear up after a decent ride.

I always use seafoam at least once per season and in winter. I just measure it according to the directions. Actually cleaned out a pilot jet while riding by having seafoam in it for storage. Lots of slowing down and taking off, using the choke, about 25 miles and it was cleaned out.

Mild winter down here, almost no snow at all and not much colder than teens for one night at a time. Plenty of 40°-60° nights/days.

Bread, that's it, bread, you need to ride to the store for bread, or just some Goody's powder.
Hey Spockster - Finally took it for a ride today. Went and got oil, filter, and filled tank with fresh gas. It did go good, but had an occasional burp in cylinder that can be felt more than heard. Got oil, crossed street to fill almost empty tank, and it didn't do it at all on way home. Minor for now. Anyway, changed oil & filter and started it. I noticed very light flickering of headlight and front blinker marker lights. Same as neutral light. Any throttle at all, and all is fine and bright. Just wondering if it just might be normal. Posted a short video on YouTube if your able to view from here.. Mike

Updated thought - I have read the idle should be set at 1,000-1,100 rpm when warm. I am sure my idle is below this, I am thinking 800-900 rpm. When I have it out next(Hoping Saturday) I will adjust idle up a few hundred RPM's. That's all it takes to stop the flickering anyway. It MAY just be too low on idle. Open to any thoughts, but makes sense.

 

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The hot start backfire is a sure sign of low cranking voltage on this bike. Do the AGM first.

That is so true. Took my first ride of the spring, thought I had enough battery charge. Started fine before I left home, stop at gas station … and sure enough a few backfires, but no start. Called the wife to bring my jump box, hooked it up and immediately stated. They do need a better charge to start hot than they do cold.
 
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