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Discussion Starter · #1 ·
Hey All,

I have a 1993 vn750. Currently I'm coastered, ear shaved with K&N pods, true dual Vance & Hines pipes with baffles. I took the carbs out and completely disassembled, cleaned and put together with rebuild kit. For Jetting I originally went with 140 hi, 40 lo, and zero shims and 2 turns out on idle screw. Bike ran good down low and up high, but hung up around 3k-4k rpms. I didn't spend too much time reading the plugs, they weren't showing too rich or too lean but I didn't do a plug chop to really get into it.

After Reading Hexxidecimus post about carb tuning and jetting, I was thinking maybe I was too rich on the low jet, this in turn making my transition circuit too rich. So this weekend I dropped my low jet down to 38 as recommended.

I also did the pickup gap mod at the same time. I elongated the top holes and filed the edge back and held a .018 feeler gauge tightly between while securing screws. After removing feeling gauge I cannot fit a .025 gauge in on either the 10 oclock or the 8 oclock, but I can snuggly fit a .024 gauge in. Unfortunately due to old wiring when I was securing the 10 oclock pickup I noticed one of the wire broke off flush to the pickup. When I pulled it back out the other wire fell of too. The 8 oclock pickup seems fine, the wires were secure.

In an attempt to salvage this, I used a very small round tip burr bit on my dremel to "excavate" the plastic around where the two wire went into the pickup. Exposing the two metal crimps inside plastic. I couldn't undo the crimps, but drilled a micro 1/64" hole through both of them. From there fed the stripped wire through the holes, twisted them in there and soldered the connections. This seemed to work fine. I then painted the solder in liquid electrical tape.

After getting the bike back together it started and has basically no balls, or nothing like it used to. Also sounds a little different. Could this just be because I dropped my low speed jet down to 38 and I'm too lean now? I had idle screw anywhere from 2.5 turns to 4 turns out and it didn't make a difference. Had very little power and just wouldn't run like it used to. Although, it wasn't getting hung up at 3k-4k rpms, it was a much smoother transition. It did seem like the bike had more power at high rpms on high jet. I haven't done a plug read yet but after sleeping on it I'm starting to doubt my repair on the pickup coil. Is there a way to test these? Is the 10 oclock pickup used for two of the plugs and the other pickup is used for the other two plugs? OR do all 4 plugs use both pickups, and having one faulty will just lessen the spark on all 4? Trying to vet this out before I pull carbs again to change the jets.

Thank you.
 

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One pickup coil for each cylinder, front-rear.

If one cylinder was dead. You would have to crank the idle setting way up to idle on one cylinder.

There's an ohm test for the pu coils in the repair manual, free download in my signature.

You could check for spark on each cylinder as an easy test. Also check for heat on each headpipe.
 

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Discussion Starter · #4 ·
One pickup coil for each cylinder, front-rear.

If one cylinder was dead. You would have to crank the idle setting way up to idle on one cylinder.

There's an ohm test for the pu coils in the repair manual, free download in my signature.

You could check for spark on each cylinder as an easy test. Also check for heat on each headpipe.
Thank you, yea I actually just found an old post from 2013 from Magna69. Sounds like the 10 o’clock pickup is for the rear cylinder. Also he dig out the plastic with a pencil grinder and soldered the connections as well. I didn’t get to check spark first as my wife was bugging me to come inside. I’ll take a look and update.

sucks no shops near me that will work on tuning this bike. One shop said no we only turn harleys... so clearly they just don’t know how to tune because it’s not that completed. And another said these carbs are a bitch and wouldn’t touch it either.
 

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Discussion Starter · #5 ·
PickupCoils.mov

Not sure if video link works, but this is what I did. Looking at it again in video, the connection seems solid, but almost looks like I could be grounding out on the mounting tab for the pickup coil? The stock one has a rubber isolator to keep it away, my repair looks like I might be cutting it close. Patiently waiting to get out of work so I can look at this.
 

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Check for spark, if it has spark, so far so good.
 

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You're probably right about grounding. That black/red wire looks like it is touching the bracket.
Could be right, watched the video on the pc and it does look close.

Put one meter lead on the solder, one on the bracket, and see if it reads anything.
 

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Discussion Starter · #9 ·
You're probably right about grounding. That black/red wire looks like it is touching the bracket.


Thanks guys, yea I think I found my issue. I got home and checked spark on rear cylinder. Not one flicker in my dark shed with a good solid ground. Looks like I’m tossing out the bush fix and will have to order new pickup.

Looks like I need to order the whole harness, possibly used on eBay. I don’t think they sell individual pickup coils with wire pigtails unless anyone knows of it.
This is a huge relief, I was starting to doubt the pickup mod and thinking it advanced my timing too much. But this is an easy fix. Cheers!
 

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It’s about a month since I did the pickup mod and I’m still impressed with the results every time. I ended up using the 0.020 gauge to gap it. So don’t lose faith in that just yet.
 

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The pickups come new with the pigtails, but they aren't cheap. About $188.
 

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The pickups come new with the pigtails, but they aren't cheap. About $188.
Ouch.

If you re-solder those wires making them a J shape, with the two insulated wires coming in together between the solder pads, then curling towards the outside to make the actual connection, you'll have guaranteed insulation between the wire and the bracket. Then epoxy that mess in place, because any wiggling of the bare wires is going to cause a break due to metal fatigue.
 

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Discussion Starter · #13 ·
Ouch.

If you re-solder those wires making them a J shape, with the two insulated wires coming in together between the solder pads, then curling towards the outside to make the actual connection, you'll have guaranteed insulation between the wire and the bracket. Then epoxy that mess in place, because any wiggling of the bare wires is going to cause a break due to metal fatigue.
yea, there honestly wasnt much to work with when soldering. I dug it out pretty good too. I can find used harnesses on eBay but they are like 67 bucks and still from the 90s and just as likely to break... I might just go that route though because if it breaks again on the road I don’t wanna get stuck on one cylinder.
 

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Discussion Starter · #14 ·
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just found this, looks like individual coils. But an aftermarket replacement... allegedly fits. What do ya think roll the dice? Or better off buying an oem used one?
 

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Well you found a lower price for a new one, with the pigtail. They claim longevity with higher resistance than stock.

Looks like they're not sure about their polarity, telling you to flip the wires if you don't get spark.

OEMs do fail internally, but it's usually the external wires breaking when they are handled. So the new wiring is pretty tempting.
 

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Discussion Starter · #16 ·
Well you found a lower price for a new one, with the pigtail. They claim longevity with higher resistance than stock.

Looks like they're not sure about their polarity, telling you to flip the wires if you don't get spark.

OEMs do fail internally, but it's usually the external wires breaking when they are handled. So the new wiring is pretty tempting.
Yea after reading more on hear I’ve seen a few post of wires breaking, I think I’ll go for it. And be the guinea pig for the rest of us.
 

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Discussion Starter · #17 ·
Just arrived in the mail, initial look over is it’s good quality, good instructions, and plenty of wire lead to play with. Install tomorrow after work let you all know how it goes.
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Black and yellow is the ground color for the rest of the bike, so that might be true of the front pickup too. If it is, then that's in the same position as the black and red wire for the rear. maybe.
 

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Discussion Starter · #19 ·
Black and yellow is the ground color for the rest of the bike, so that might be true of the front pickup too. If it is, then that's in the same position as the black and red wire for the rear. maybe.
Yea that was my thought too, usually if there’s a polarity assigned to it, and one of the wires has a black stripe, that’s negative. I’ll try that first and let you know
 

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Discussion Starter · #20 ·
Well bracket is the right length, the wires come out in a different location but enough to clear. The problem lies in the shape of the bracket the placing the pickup insanely far from the magnet. I did this to gap them to .018 and this one is way away. Like drastically away. Look at the feeler gauges I fit smoothly in. Magnet is in place too. This of course is with NO filing of bracket. But I measured bracket versus the feelers I pulled out without filing. And it looks like there won’t be enough material to file away to move the pickup close enough. So it’s not worth filing, having it come loose and destroy the bike. Also while killing my ability to return it. But damn I wanna ride tomorrow! Anyone have any suggestions as to if this is saveable?
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