One Cylinder

[Mr Tuscan]

Hi everyone

Got a engine issue, lost a cylinder, appears to be no spark but coil on ht lead seems fine as tested it.
It’s going into my local shop about 3.5 miles away, can I ride it in or should it be collected.

Pretty sure this is a wiring issue and not mechanical but.....

[Jug]

I dunno, I'd test ride it and see how it runs, if it's too lumpy then I'd get it collected.
My Superduke ran on one cylinder earlier this year when I got water in one of the coil packs, the engine sounded very rough until it cleared. Having heard it run I doubt I would ride that on just one but it is a very different V-twin to yours so maybe yours will run smoother like that.

Does yours have 2 separate coils or one coil with 2 leads?
How do you know the coil is good, have you put a spark plug on it and tested it against the head?

[Mr Tuscan]

Two coils, one for each lead.
No spark from the back lead against the head so I put the lead on the front cylinder wiring and it sparked against the head so concluded the lead and coil was ok!?!

There is power to the rear coil pack as I can see a small blue electrical connection ‘fizz’ when connection the two spades to the coil which puzzles me.

Beyond this I have to put my hands up as I’m not an electrician or mechanic.

The bike has been washed and I moved my rev counter around so it’s stopped working after the two jobs whether either is significant to the fault appearing I have no idea.

But I’ve decided to stop tinkering at this point in case I confuse or make matters worse.

By the way the rev counter has been removed from the bike to be sure it’s not causing problems somewhere.

The light inside the rev counter started to work intermittently and then stopped altogether so there is always the possibility that a short circuit has happened and caused something to quit, I’ve checked every fuse I can find and all are good, so time for the experts I think and hopefully it’s nothing to serious or expensive.

Think I’ll get it picked up

[Mr Tuscan]

Garage has been in touch three days later to say it’s looking like the CDI ignition unit has failed but they will look again on Tuesday with another engineer to confirm as the unit is expensive.

When I asked how much they indicated between £600 - £850 prior fitting

Erm it may be a while before I respond to any replies here as I’m currently looking for a spatula to scrape myself up

!!!!!

[Jug]

Get the bike back and get a used one off fleabay, or see if they will fit a used one for you.

£150 on fleabay..

https://www.ebay.co.uk/itm/Yamaha-XVS65 ... SwaC9aaMzf

Problem is... if they aren't sure what the issue is they'll just start changing things until something fixes it, which can be an expensive way to find an issue. At least with used parts you can resell them if it isn't the problem.

Is there anyone on a Dragstar forum that is will to test their CDI on your bike, or yours on theirs?

[Mr Tuscan]

Ive been thinking the same, I’m hoping tat if they decide that is the issue, there will allow me to supply them with a second hand unit, ive been searching eBay and so far only seen the type you linked to, mine is the earlier version 1997 - 2003 with 2 sockets rather than one.
Found one on German eBay for £199, so ill see what they say come Tuesday and go from there.

Sadly no one on the DragStar group is a local person as that would have nailed it solid.

[Jug]

Sadly no one on the DragStar group is a local person as that would have nailed it solid.

You could ship your ECU to someone to test for you (if they were willing), and If it is proved to be faulty then you wouldn't want it back anyway.

With your bike being old school (carbs ect) the ECU is little more than just a CDI so there isn't much chance of causing issues on another bike by swaping ECU's.
I'd do it, and would be happy to test someone else ECU on my trail bike, but not my newer road bikes as that would be pointless as they have immobilisers built into to the ECU's.

[billinom8s]

Were those ecu units used on any other model of Bike?

[TLS-Moose]

ECU repairs has become a rising business in recent years, and it's possible to save hundreds of pounds. Electro-diesel in Exeter arranged for the repair of one for me some years ago
There are several out there if you Google .... Here's one that mentions motorbikes ..... https://www.jtntecu.co.uk/

[MikeZ]

If you've got power to the coil, and you're happy that the coil works ok cause you swapped it to run the other cylinder. Then you're not getting the on/off voltage change to the coil, it's the voltage change that causes the spark. So i would. . . .
Set multimeter to volts and with the ignition on, and engine turning over at least on the starter, see if it reads at the connector to the coil, this will tell you if the 12v feed is varying.
If not then it has to be the low voltage feed to the coil.
Then follow the wires up the the next connector and try again etc keep following until the last connector at the pickup coils, this way you will know if it's wiring, or ignitor unit, or the ignitor pickup coils.
It's usually just a wiring break or bad connection, but ignitor units or pickup coils do sometimes fail.
Often washing causes problems with the 12v side of the ignition circuit, washing bikes is bad news (that's my excuse for not doing it).
Best of luck.

[Jug]

Often washing causes problems with the 12v side of the ignition circuit, washing bikes is bad news (that's my excuse for not doing it).

LOL

Earlier this year my SD got very dirty so I gave it the wash of it's life, it took hours...
It looked immaculate, and rewarded me for my effort with a misfire on the rear cylinder that lasted for a few seconds on each cold start.
I eventually found the cause to be damp around the coil pack, and cleared it with a few blasts of air from my compressor directed into the spark plug well drain hole.

[Mr Tuscan]

Thanks for all the input everyone, I took it all on and moved forward with it, I've added to my diary