Sick of my VFR, One problem after another! (Electrical)

I'm some poor fool who bought a previously raced and then neglected 1996 Honda VFR750F.

I've not ridden this bike NO MORE THAN 100 miles this year and I've done just about everything imaginable to this bike.

- Repaired broken plastics with Fiberglass and epoxy
- Repaired Fuel sending unit
- cleaned and rebuilt the carburetors
- fabricated new speedometer socket for the speedo sensor
- replaced all engine gaskets on front and back cylinder banks
- bought a new battery
- new brake lines
- flushed and rebuilt brakes
- replaced old tires
- replaced old fuses and bulbs
- replaced old grips
- replaced bar end mirrors
- replaced chain and sprockets
- sanded, primed, painted and cleared (exhaust paint, primer, and clear)
Just to name a few things!

I've got everything back together, now she's not pretty but she *should* work, unfortunately now I can't get (enough) spark. I tried the quick fix to buy new plugs from my local auto shop, but with no luck.

I'm desperate and at my wits end and honestly if I hadn't sunk too much money into this to give up, I'd part the damned thing out and sell it for scraps.

Exhausted and frustrated I come to you all for help, where's the next potential issue to check and troubleshoot?

Spark plugs are old but were working and running the bike a few months ago, so they *should* still be working.

The battery is fully charged, all other electronics work, compression is solid, fueling is good. All I'm left with is embarrassingly weak orange/yellow sparks. I've gotta get this thing running again, please if anyone can help then let me know.

 

Check the connection to the coils, spade lugs become corroded. You have done so much already. It's hard to blame an abused bike, no matter the make or model.

 

What has been worked on or changed since the last time it ran? I would make sure the plugs are the correct Denso or NGK. You also might check the resistance in the plug caps and for that matter wires. As mentioned above the connections all need to be clean and shiny.

 

Spade connectors at coils are same type of connector that corrodes and fail at starter-solenoid and RR. Measure voltage at both coil terminals before & after. Clean off oxidation on male connector and replace female side by crimping, SOLDERING and adhesive shrink-wrap over new nickel-plated terminal. It's done this way in pro-motorsports, aerospace and military applications for performance, durability and reliability.

All to prevent hair-pulling frustration you're going through (or worse). Planes have fallen out of sky due to bad wiring. If it can be done better, I do it. Now's your chance to fix and improve on factory designs. There never seems to be enough time to do it right 1st time, but there's always time to do it again! Often in total darkness on side of road in pouring rain!

 

Thanks for the advice, to clarify I don't blame the bike at all. VFRs are such beautiful pieces of machinery. My only gripe is with life and everything getting in the way I have been working on this bike for a little under a year and I really just want to enjoy it already.

 

I've checked my plugs and need to double check the gapping, I've ordered new replacement NGK plugs since these ones appear to be at end of life anyways. I wouldn't be surprised if they're the original plugs that came with the bike 55K + miles ago.

I've investigated everything and it appears that both male and female spade points are both covered in light corrosion. I've started pulling them off the bike and will pull out the soldering kit this week to solder on new female points after polishing the male points.

Thanks All for your help!

 

Do NOT solder the new connections on crimp them. Solder is known to fail under vibration.
I would replace plugs, caps and leads. Will it fire up if you use easy start? If the bike was running properly a few months ago what have you changed. Could it be the carb clean that has done it. I have worked on a few non runners that have turned out to be carbs incorrectly set up after a clean.

 

I remove the plastic on the butt connector, I use aviation grade clear shrink tubing, 1. Crimp 2. Solder 3. Shrink tubing = job complete

 

Your harness is divided into 2 different wire gauges,,.. High Current & Low Current.
When connectors are crimp'd ON at the factory, the Copper Strands and Crimp Connectors are clean and fresh, will work fine,,.. for a while.
After 30 years the Copper and Brass will corrode, there will be less and less contact for current to pass thru and the crimp/wire will heat up (and corrode more/runaway) till it burns.
Solder ALL high current crimps (use FLUX);

Shown here is a Regulator/Rectifier connector.

Pull out the High Voltage wires from the Coils, carefully scratch up the corroded brass pin inside the coil.
Take the HV wire (coil end) to a grinder wheel and "grind" off a few mm till you can see fresh wire in the core.
Solder the coil wires crimps. Wiggle the connector onto coil terminals to freshen up the metal.
ReSeat the connectors at the CDI boxes near the tail light.
If still no spark consider opening the CDI boxes and resoldering the Connector Pins at the Circuit Board and the FET.

I have had to replace a bad FET on occasion.

 

Still like to hear what was done since it last ran.

 

Update, it's running, I tried polishing up my ignition coil plugs and no real luck. Ordered new coils on a whim for $50 and the bike jumps to life. She had her first test run around the block today.

To answer your question, since she last ran I had rebuilt the Carbs, rebuilt the top half of the engine (front and back cylinder banks), and all of the loose odds and ends that go along with those two tasks.

*Edit*

In addition to swapping in the new coils today, I also popped open the carbs bowls again to reset the float height and the carbs are working perfectly.

 

This is excellent information! thank you for the detailed reply and for the pictures!

 

To clarify: my plan was to crimp, solder, then shrink wrap them as suggested by Dannoxyz

 

More crimped connections fail than soldered by far. Depends up on load and SN-cycles. By time soldered connection cracks, solderless connection would've completely broken apart. It's like saying build bike-frame from rubber instead of metal because when it fails, it'll bend instead of snapping. By time metal frame fails, rubber one would be well past useless.

It's not black & white, all-or-nothing comparison, needs to have numbers. A crimped+soldered connection will easily last 10x longer than crimped one. And you need matching crimper-die that squeezes OD, not just pinch it. Up until '60s, kids in school were taught to tie wiring and solder properly. It was only in '70s with drive for fast and cheap production that auto-makers adopted solderless crimping and reliability took nosedive.

Aerospace and military equipment are not allowed to be crimped-only for reason. Everything is tied/crimped, soldered and adhesive shrink-wrapped.


When I made my ECE headlight upgrade kit with new harness & battery-cables for Porsches decades ago, I used this wiring manual. Everything was crimped, soldered and adhesive shrink-wrapped. Came with 50-year warranty. That was 25-years ago and not a single one has come back. People actually remove my harness to transfer to new cars. They come up on eBay regularly going for double what I sold them for.





Also built lots of harnesses for aftermarket programmable ECUs, programmed and dyno-tuned them.


I built this TechEdge wideband O2 in 1995 to tune my race-cars and bikes. All soldered components haven't fallen off circuit-board yet due to vibration.



Wouldn't you want your VFR harness to last 50-years without any trouble?

 

BTW, whenever replacing corroded connectors, don't repeats Honda's mistake and use penny-pinching bare-brass connectors. Get tinned-coated connectors to prevent exact same corrosion-problem from happening again.



Also note that highest-power 1/4" spade-connector is rated for 24-amps. Honda uses it in 30-amp circuit!

 

Nice write up along with the pictures, I learned some things and like your analogy about building a rubber frame motorcycle. You work for NASA or something? LOL Peace

 

Why thank you! Heh, heh... yes many decades ago I worked for one of NASA's subsidiary research branches in Mt. View. Although my main job was extracting and analysing info from data-recorders (black-boxes), I got involved with plenty of wiring and destructive testing.

We'd put everything into thin metal case: recorder, all sensors and wiring, and drop it out of helicopter a mile up. Then scoop up remains and toss into fish-tank filled with water from Bay. Then let it sit for 2-weeks before pulling it all apart to analyse. I learned a lot about what it takes to make wiring survive 200-mph impact along with salt-water bath afterwards.

Edit - with opsec and clearance, this is not exactly how it was done. Similar effects and results though.

 

Super interesting, when I was working at a repair station and I had down time, there was a an aircraft manufacturer named Crane, well their manuals were beyond the minutiae of soldering, I honed my soldering skills reading those pages. From how to strip wires properly for aviation, to deep soldering. I always wore good magnifier glasses to watch the solder joint/cup harden. Cheers

 

Excellent information, one thing I didn't see was a warning about 'cold' solder joints that happen when there is movement before solder cools to a solid. If you suddenly see solder joint turn gray and have a crystalline look, reheat until solder is shiny.

 

Ah yes, soldering technique very important! In '90s, there was alot of issues with OEM wiring and ECUs. This was caused by huge batch of faulty electrolytic capacitors hitting market. Affected everything from ECUs, TV, microwave ovens, computers, clocks, etc. Another factor making things worse was shift to lead-free solder. Horrible stuff, it would glaze up right next to soldering-iron tip!

In past couple decades, pro-motorsports has actually surpassed aerospace/military standards in wiring. MotoGP and Formulae-1 are pushing performance envelope using microscopic 22ga and smaller aluminium wiring for weight-savings. Specialised solder for materials and tapered strain-relief shrink-wrap tubing. Amazing stuffs!