will not start/backfiring - Page 2 - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #11 of 27 (permalink) Old 11-05-2010, 10:08 PM Thread Starter
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just so there is no confusion, the bike backfires while cranking, it does not starts, it just backfires while cranking
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post #12 of 27 (permalink) Old 11-06-2010, 02:55 AM
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Originally Posted by nicknack2 View Post
I understand the easiness of having lifetime plugs and 0-maintenance battery, but how does that relates to the backfiring, I'm not worried about the no start-the air/fuel mixure at this time, my main concern right at this time is why is it back firing, it appears as if it was out of timing...
The timing is not adjustable. There is no distributor or ignition points, it is electronically controlled. As far as I know, the only way the timing can change mechanically is if the cam chains and gears become so worn that the chains jump a cog.

If your new battery has plugs on top to allow adding water, it is a wet cell, not maintenance free. I started my bike last week after it has sat for 3 or 4 months w/o being started. My MF battery was new in April, and cranked the engine over for several seconds until the vacuum operated petcock let fuel fill the carbs, then it fired right up on Seafoam treated fuel that has been in the tank since my accident 28 months ago.

Pull all the plugs and examine them for wear and if they are wet. If any electrode edges are rounded off by spark erosion they will need more power to create a hot spark. The Iridium plugs have a harder electrode surface and resist rounding off for up to 100K miles.

Not sure about backfiring, but it may be caused by too lean fuel mix I think.

Gordon

1991 VN 750 -"Cosmic Lady" or "Bad Girl"?
Purchased May 16, 2008
Approx.19,300km (12,000 miles)

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Relocated R/R
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July 13, 2016, Riding on the DARKSIDE now, Classic Radial 165/80-15


TOP TEN THINGS A NEW RIDER/OWNER SHOULD DO. Click on link.
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post #13 of 27 (permalink) Old 11-06-2010, 11:07 AM Thread Starter
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I agree, lean air/fuel mixture will cause backfiring when decelerating and pinging while accelerating, but w/ the choke wide open the mixture it is really rich... like I said the problem is while cranking...I know there is a tech/mech in the forum that has my answer...
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post #14 of 27 (permalink) Old 10-11-2016, 02:58 PM
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I'm interested to find this out because my 86 VN750 is doing the exact same thing!
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post #15 of 27 (permalink) Old 10-11-2016, 03:01 PM
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I have been having issues for months and I have to jump start the bike every time I stop. Please help us
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post #16 of 27 (permalink) Old 10-11-2016, 03:41 PM
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have you played with the idle screw make sure it didnt back out of the adjuster on the carb mine did and i had the no start backfire just like that took me a while to find the problem
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post #17 of 27 (permalink) Old 10-11-2016, 03:44 PM
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AGM battery and iridium plugs solved my problems. Same with just about everyone else here. Do not bother running a standard battery with cheapo plugs.

Pickup coil gap mod and pickup coil relay mod also greatly improve ignition.

1986 Kawasaki Vulcan 750
NGK Iridium Plugs #7803/DPR7EIX-9
Duralast Gold ETX15 AGM Battery
Coastered & Shaved
TOC MCCTs
Metzeler ME880 [110/90-19, 170/80-15]
Balance Dampers Replaced
Tuxedo Mod
Rebuilt Forks w/ Progressive Springs
V&H Cruzers
VN750.com Grill Cover
Meanstreak Seat
Emgo 23-92411 Handlebars
MOSFET FH012AA R/R


1990 Kawasaki Vulcan 750

1998 Honda VFR800 FI

2014 Honda VFR800F

1989 Pontiac Firebird Formula 350
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post #18 of 27 (permalink) Old 10-12-2016, 11:22 AM
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@Matthew Wellington : When I purchased my vn it came with a 'new battery', but after a few months it started dying every time I parked it. New battery solved the problem. If your bike starts with a jump, it means you've got low voltage or insufficient cranking amps from your battery. Try cleaning your battery terminals and take your battery to a car-parts store for a health check.

1992 US-nonCA * tuxedo mod * r/r relocated

Vulcan slang for newcomers
Service Manual Download
Wiring Diagram + annotations * still undergoing revisions, but still more useful than the generic one. Let me know if you find mistakes or think something additional should be added
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post #19 of 27 (permalink) Old 10-12-2016, 11:46 AM
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talking about no maintenance batteries, can someone give me the reference/part number of the one needed for the 750 please.
also, i currently run with standard NGK's , are the iridium that much better ?
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post #20 of 27 (permalink) Old 10-12-2016, 12:38 PM
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Quote:
Originally Posted by Malta Mick View Post
talking about no maintenance batteries, can someone give me the reference/part number of the one needed for the 750 please.
also, i currently run with standard NGK's , are the iridium that much better ?
Yes the Iridium are *that* much better on our bikes (our ignition isn't exactly the best, so anything helps). NGK Iridium Plugs #7803/DPR7EIX-9

Here is a list of batteries: Batteries - Vulcan750.net Wiki

1986 Kawasaki Vulcan 750
NGK Iridium Plugs #7803/DPR7EIX-9
Duralast Gold ETX15 AGM Battery
Coastered & Shaved
TOC MCCTs
Metzeler ME880 [110/90-19, 170/80-15]
Balance Dampers Replaced
Tuxedo Mod
Rebuilt Forks w/ Progressive Springs
V&H Cruzers
VN750.com Grill Cover
Meanstreak Seat
Emgo 23-92411 Handlebars
MOSFET FH012AA R/R


1990 Kawasaki Vulcan 750

1998 Honda VFR800 FI

2014 Honda VFR800F

1989 Pontiac Firebird Formula 350
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