No spark on number 3 87 vfr700f2

Hi all.
I earlier posted the dyno results on the 1987 700.
Turns out I have no spark on number 3 cylinder.
As you can see in the picture this plug is like new, even though its been in since the last service, 1500 miles ago. I have run it like this for 3 years and not known. I have swapped everything over. All coils work. All plug leads work with plug caps. I think the cdi is fubar'd. Now the search for an 1987 vfr750/700 cdi begins.
Can these be fixed or is it an ebay job.
Unless someone knows better.
Thanks for all the help you guys have give me so far.

Roger

 

Yep it looks like new. Just one thought - you say you swapped everything around to try and identify what was defective - I assume you tried running that plug in another cylinder. Many years back I did a basic oil filter plugs service on a Ford Fiesta and found the car down on power - eventually found one of the new plugs was not firing (never figured out why) but after refitting one of the old set and the car ran fine.

Good luck with the parts hunt.



SkiMad

 

Hi
I managed to get the cdi repaired.
Turns out the previous owner had cut out the fuel pump relay and joined all three wires together, thus blowing one of the output transistors.

Roger

 

You got the CDI repaired? By who and for how much? Any chance of pictures?
Thanks
Garry

 

Bypassing the pump relay is a good idea (imo), but the only 2 wires that skould be connected are the blue/black and blue------not the yellow/red.

 

Sorry no pictures.
A small bike shop close to where I live in the UK has an electronics guy as part of the service team. He does is as a hobby I think. He tested it in the shop, took it home and brought it back half an hour later. If
They charged me for an hours labour, a new plug lead and cap.
66 English beer tokens. About $100 US.

http://www.bikesandbeyond.co.uk/

 

Hi
My 700 is an 87 f2.
It has different colour wires.
Roger

 

A decent bike shop by the sounds of it. You are very lucky to have that on your doorstep.

 

Thanks for the update Roger

Its really good to hear you have sorted the problem and took the time to let us all know how it was resolved.

One inherent weakness of all forums, is that when some people manage to fix a problem, they forget to provide an update to share their solution and knowledge.


Hopefully you will now be able to enjoy a few good weeks on the VFR before the weather turns. :vtr2:


Take care



SkiMad

 

I'm still a little confused, 2 coils, wasted spark and one cylinder not firing, can this happen? and if so how?

 

Ok
Let me try to explain.
Firstly each cylinder has its own coil.
Each coil has its own feed from the cdi unit, abit like a quadrophonic hifi system.
If one of the channels in the quad amplifier fails you only get sound from three speakers.
Some idiot that owned the bike before me decided it would be a good idea to remove the pump relay, but instead of just connecting two wires together he thought to connect the sender wire that actuates the relay to the other two wires.
This caused the transistor on one of the cdi channels to blow.
No channel no spark.

Roger

 

4 coils, that makes sense, I can see why that wouldn't work, so 86 2 coils, 87 4 coils interesting to know

 

No
All vfrs have 4 coils.

Roger

 

Of course my bad I forgot about the 2 hanging off the frame, so I still have another question , how do they trigger the CDI from the crank, do they use 4 pulse coils somehow. Not important just curious

 

Picture of 1986 pulser unit




Picture of the 1987 pulser
units.

 

Thanks artee, so my thinking with 2 pickups it must fire 2 coils at the same time thus a wasted spark on one cylinder? If this is the case I wonder why they stopped using twin outlet coils? Maybe they couldn't mount twin outlet coils without having very long plug leads to the front cylinders?

 

Where is the cdi box located?? I believe mine is pooped but cannot find it or its just in my face and I cannot see it

 

Under the tail section.
Get a manual.

Roger

 

I have a manuel but I have looked over the entire bike and havent found anything to look like a cdi box with the capicator .. only thing I have found is just under the tail but looks nothing like pictures for a spark unit

 

Black box about 4x3 inches with two red plugs coming out.