96 VFR750 no spark from #4

[nicoAK]

Hi all,

New to the VFR scene so take it easy on me please 😅

Recently bought a 96 VFR750, after the previous owner passed away, for £600 and a promise to his wife/widow I’d get it back on the road again…but I’m starting to think I might have to break that promise 😫

Last MOT’d 2012 so I kinda knew they’d be some work to do but mechanically the bike is actually sound…brakes, clutch, carbs, steering column bearings, exhausts etc are all in good condition which surprised me.

Now this is where I get lost 😂 there was no spark on cylinder #4 (front right as you’re sat on the bike) and I couldn’t smell fuel. Swapped coil4 for coil3 and it worked but coil3 still wasn’t firing in cylinder #4. So all coils work fine but not when they’re in #4.

Found the previous owner had chopped some bits and wired in his own relay near the CDI unit, and I’m sure it involved the red/yellow wire for coil4 but can’t remember exactly.

Instead of spending hours/days/weeks chasing wires I bought a 2nd hand loom from eBay so everything would go back to standard…or so I thought…everything all plugged together but still no spark on #4 🤬

So my plan now is to purchase a 2nd hand CDI unit and hope that will fix it, maybe?

Can somebody/anybody help with suggestions as to whether I’m on the right track…or a wild goose chase 🤣

Any help will be very much appreciated 💙

[Captain 80s]

Used CDIs for those bikes (with return policies) are relatively cheap.  If that is a better route for your then proper electrical testing, that could very well be the culprit.  At least you will know, and the chance of another CDI having the exact same issue is VERY low, as they are not known (to me) to be fragile.

 

Good luck.

[tsmitty]

make sure that spark plug hasn't taken a dump. 

 

[Captain 80s]

1 minute ago, tsmitty said:

make sure that spark plug hasn't taken a dump. 

 

 

Exactly.  Suggestions are often made assuming the basics have been covered and some body is genuinely lost.

[nicoAK]

Thanks for the help guys.

I’ll be honest Captain, they may be simple on an old bike like this but electrics have never been my strong point. I wouldn’t have a clue what any volt meter readings mean or if I’m even testing the correct wire 😢 that’s why I put all my hope on a used loom fixing the problem.

There’s a breakers local to me in Leicester that have one for £50 but they do a no returns on electrical items. Looks like I might just have to bite the bullet and hope for the best.

And tsmitty the plugs are all brand new NGK Iridium and they all have a healthy spark when they’re plugged to coil 1-3 just nothing from #4.

Thanks again

[Captain 80s]

11 minutes ago, nicoAK said:

Thanks for the help guys.

I’ll be honest Captain, they may be simple on an old bike like this but electrics have never been my strong point. I wouldn’t have a clue what any volt meter readings mean or if I’m even testing the correct wire 😢 that’s why I put all my hope on a used loom fixing the problem.

There’s a breakers local to me in Leicester that have one for £50 but they do a no returns on electrical items. Looks like I might just have to bite the bullet and hope for the best.

And tsmitty the plugs are all brand new NGK Iridium and they all have a healthy spark when they’re plugged to coil 1-3 just nothing from #4.

Thanks again

 

With return policy in UK

 

eBay VFR CDI

[nicoAK]

Thanks for that Captain.

I’ve been looking for the last couple of days and found there’s quite a few 94-97 units on there, most between £50-£80.

The code is very similar to mine but the last 4 digits are different, mine is 6227. So my next question is…do all CDI’s have different codes so I can use any or do I need to find an exact match?

Many thanks

[Captain 80s]

Any 94 - 97 CDI is applicable.  No differences.

[nicoAK]

CDI unit arrived in the post this morning…fitted to the bike this evening.

SHE LIVES TO FIGHT ANOTHER DAY!

I’m so happy right now!

It was really starting to fry my brain so I genuinely cannot thank you all enough for helping a random stranger 😅

[Captain 80s]

Hell YES!!   Very cool. 

[willybum]

My problem is my front 2 cylinders have no spark but the rear 2 do.....coils are good changed CDI box...any suggestions

[Grum]

3 hours ago, willybum said:

My problem is my front 2 cylinders have no spark but the rear 2 do.....coils are good changed CDI box...any suggestions

Refer to your other posting!!

[nicoAK]

On 4/26/2023 at 2:43 AM, willybum said:

My problem is my front 2 cylinders have no spark but the rear 2 do.....coils are good changed CDI box...any suggestions

Sorry but I can’t help you there.

Looks like you’ve had a reply on your original post about checking the pulse generator. It would probably be wise to check the said item as that sounds like a good place to start. Even if it ain’t that, it will give you peace of mind that you’ve had it off and checked/cleaned it.