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Starting problem

4K views 26 replies 5 participants last post by  MSattler 
#1 ·
So I got stranded again today... it’s becoming a common theme... it would run for a little bit. And when I went to stop, it would die. After pushing the bike a mile home, I put it on the charger, and a second later, it was firing up. But, if it died, it would not start again. This video is from when it died in a parking lot behind my house, and in real time. https://vimeo.com/345224081
So then I went to do the coil bypass mod. It seems to be turning over much quicker, but it will not start. I took out the front and rear spark plug, held my finger over the boot, and no spark now. I ran the wire to the front coil, a wire to the back coil, and a third wire to the relay with a ton of flux and solder. I am assuming a bad connection? Advice would be appreciated. I am not sure if the issue from earlier was resolved, as the bike won’t start.


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#2 ·
You did the mod as in the pic, yes?

I don't think you get the spark holding a finger over the boot. Try placing a phillips screwdriver in the connection in the boot and hold the exposed metal shank of the screwdriver close to the cylinder. 1/8 inch off. Crank and see if there's a spark from the screwdriver to the cylinder. Helps to do it in a dark garage or night.

If you see a spark, th mod should be OK.
 

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#3 ·
You did the mod as in the pic, yes?



I don't think you get the spark holding a finger over the boot. Try placing a phillips screwdriver in the connection in the boot and hold the exposed metal shank of the screwdriver close to the cylinder. 1/8 inch off. Crank and see if there's a spark from the screwdriver to the cylinder. Helps to do it in a dark garage or night.



If you see a spark, th mod should be OK.


That is the one that I did. I took out the spark plug while attachéd to the boot, held it next to the block on both cylinders, and no spark. I will go back over the wiring today to see what it was, but I would think the red wires first, since neither coil was functioning.


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#4 ·
Yes, check the red wires. Also the relay trigger wires. If you have a meter check the relay also. When I did the mod the first relay I bought was bad out of the package. It "clicked" when I turned on the ignition but didn't complete the "hot" circuit.
 
#5 · (Edited)
Okay so when the ignition is on, 87 becomes grounded. This is going to the two coils. I do not have a multimeter, so I will try a new relay. I got it from autozone, so swapping it shouldn’t be a problem. I just checked again, there was no spark at either cylinder, but the relay clicks as soon as the ignition is turned on. Hopefully this will solve the dying at low RPMs and not starting issue too
*update*
I just hooked it back to factory and it fired right up. I think the relay could be bad. It was over 90 yesterday, maybe this is the hot start issue?

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#6 ·
Relay could be bad. Mine was a Bosch so everybody can have a "bad day". If going back to factory and it started cold that's good. I think the hot start issue is when the bike is restarted after the engine is hot from running.

Check the spade connectors on the new red wires to make sure they're good. I used crimp on and missed a connection. You should get a meter. With the electrical on these "old" bikes having other issues you need one.

If it runs with the old wiring, ride it around the block a few times, shut it down and restart to see how it does.

Do you have an AGM battery or flooded/wet cell? These bikes really like the AGM and need 12+ volts for starting. Might want to have the battery load tested.
 
#8 ·
Good morning, Spockster! was hoping you'd join in!

MSattler, Spockster has the knowledge to get to the problem faster than I do!
 
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#9 · (Edited)
'morning! Nah, you're doing just fine.

Load test and charging volts for first two steps troubleshooting the dying/starting problem, after getting spark back.

If that's a Walmart wet cell, it carries a higher percentage probability of being weak.
 
#10 ·
Thanks!

A new AGM. iridium plugs and the coil mod cured my hot starting issues. Look at Spockster's 2 wire mod. Cured some other problems I had.

Well, after this is solved! :~)
 
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#12 ·
Thanks!



A new AGM. iridium plugs and the coil mod cured my hot starting issues. Look at Spockster's 2 wire mod. Cured some other problems I had.



Well, after this is solved! :~)


So far I have done the two wire mod, and the blue wire mod, thanks to Spockster. I have the ear shave mod, 42/142 jets (I found a nice man who wants to trade the stock exhaust for a Vance and Hines set. No way I could say no, so those will be going on in a couple of weeks), and I plan on doing the coil mod that UberTallDude sent me with the .20 depth. I would like to make this my daily rider bike (keep the miles off of the other one), but this is killing me.


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#11 · (Edited)
I have a cheap wet cell. I will replace it soon though. So I got the new relay, and it is not clicking now. Here’s the three wire splice. One to the front coil, one to the rear coil and the third wire to the relay. I am using 12ga wire.


Here’s the relay. The orange wire is the inline fuse with a 15 amp mini breaker. Black is ground to the left side 10 pin bracket bolt. The bottom red one is the stock coil wire. Am I missing something here?

*edit*
Anecdotal, but the front coil red wire is positive, as is the back coil, when ignition is on. Yet, the new wires are not positive, rather they are ground. Thus, the coils are getting two negatives, which wouldn’t make them crank. I’ve checked the wiring about 5 times, so I am confused as to what is going on here

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#13 ·
check wire location on relay.

trigger positive to relay 85, trigger negative to 86, battery positive to 36/30, coil positive to 87. Check the fuse.

Try using a jumper from another switched positive instead of the original coil wire. Maybe the switched accessory positive under the right side cover. I used the one in the headlight bucket.
 
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#14 · (Edited)
It's hard to switch back and forth from the diagram, and orient the relay in the pic, ... but .. It looks like the trigger +, and + to the coils might be reversed.

edit: See if terminals 86 and 87 need reversed.

86 should be trigger +
87 should be + to coils

 
#15 · (Edited)
I don’t get it. I have the two coils on pin 87, the old coil positive on 86, the inline fuse on 85 and the chassis ground on 30. 87, 85 and 30 are all negative.


So it is negative with the ignition turned... so when the relay closes, it is completing the circuit for ground. I have to have something backwards
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#17 · (Edited)
I am an idiot. The inline fuse goes to positive. I am glad this post is here to capture my blonde moment.
 
#18 ·
It happens. Was starting to think I was cracking up though. :nerd:

Swap them around and see where the wire on terminal 30/36 is coming from.

I would unscrew those battery caps and see if any cells are dry.

Hench did it posting that diagram. :smiley_th
 
#19 · (Edited)
I now have three positives. The power to the two coils on 87 is now positive, 86 is the trigger from the old rear coil, 30 is hooked straight to the.l battery positive, and 85 is going to the chassis connected to the bolt top left bolt above the JB.
I got shocked by the spark plug boot, so all is well. I can’t try out the bike though:





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#20 · (Edited)
Stepped away for a bit. Glad to see it's fixed! Good job, guys!

Paint is looking good! Clearcoat or flat finish?

I'm back to finishing the solar for the sidecar! :~)
 
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#21 ·
It is flat black. I think I need to sand the side covers more and redo them. I wonder if you’re supposed to sand between the final coats for the finish, like wood? I put three light coats on in 20 minutes per the instructions. This is my first time painting.
You have a side car! I want one so badly, so we can take our little boy with us on rides.

Where’d you get the sidecar?



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#22 ·
Found the sidecar on Facebook marketplace. 25+ years old and the tub needed drilling to mount on the frame. Never been used.

The VN750 isn't sidecar friendly. You'll have to make a bottom leading mount as the exhaust, radiator and bottom hose is in the way.

If you get one it should be 1/3 the weight of the bike or more. Even then you'll need about 100 lbs of ballast starting out to help keep the sidecar on the ground while you learn right-hand turns.

Changes handling drastically. Light rear brake in lefties, throttle in righties. Steer right to go right, ect. Your motorcycle reactions are out the window in normal riding. Until the chair comes off the ground then you're back on a motorcycle! :~)

This is my 4th sidecar rig. Once you get used to it you'll love it.
 
#23 ·
Found the sidecar on Facebook marketplace. 25+ years old and the tub needed drilling to mount on the frame. Never been used.



The VN750 isn't sidecar friendly. You'll have to make a bottom leading mount as the exhaust, radiator and bottom hose is in the way.



If you get one it should be 1/3 the weight of the bike or more. Even then you'll need about 100 lbs of ballast starting out to help keep the sidecar on the ground while you learn right-hand turns.



Changes handling drastically. Light rear brake in lefties, throttle in righties. Steer right to go right, ect. Your motorcycle reactions are out the window in normal riding. Until the chair comes off the ground then you're back on a motorcycle! :~)



This is my 4th sidecar rig. Once you get used to it you'll love it.


That is awesome. I’ll have to look into it! The wife and I got rid of FB, so I’ll have to see what else is out there. Do you mind if I ask the cost?


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#24 ·
The cost? No I don't mind. It was a "barn find". $350.00 for the tub, frame and mounting hardware. Came with the wheel upgrade to wider tire. Had to have swing arm worked on to fit new axel added $175.00. Was flat gray, paint to match bike added $75.00. New seat is a boat seat at $50.00. New front mount $60.00. So around 700 bucks. Java makes Velorex and there's several models. 562 is the basic model.

New sidecars range from $2000 to $8-9000. Google "motorcycle sidecar vendors" you'll see Rocket, Hannigan etc. Try CycleTrader and even eBay. You'll find nice European tubs there for 3-500 bucks but 2000 shipping!

I've attached the Velorex install pdf so you can see what's required for attaching and aligning a sidecar. All pretty much attach the same. Whoops file is too large. Google "mounting a sidecar if you're interested. Takes time but isn't hard to do.

If you get one, you'll scare the bejusus out of yourself every ride for the first couple of weeks until you unlearn motorcycle habits. But once you get on to handling you'll love it. 120 pounds of ballast works wonders. Out for a ride and suddenly need to stop at the store? No problem! You'd be amazed at the volume of groceries you can put in the car. (downside, you'll probably go to the store more often instead of the wife!)

Caveat. NO passengers on the bike. You'll need to keep that side as light as possible.

Again the VN750 isn't that "friendly" to mounting a sidecar. You will have to make a front bottom frame mount. The rear mounts will go on as will the front top mount but frame mounts, the radiator and lower cooling hose make the front bottom mount impossible to fit. Even so, go for it!
 
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#25 ·
I had a problem yrs ago that my engine would stop... and my first thought was that I was out of gas.
It would stop when I opened the gas cap and let the bike sit for 15 min. Then I’d put the choke on and it eventually got enough gas to restart.

So was a plugged gas cap vent or something causing a vacuum to starve the carbs? Don’t know.
Problem went away and hasn’t been back for 8 yrs....hmmmn
 
#27 ·
I got fat after I got married. It was probably good for me


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