No sparks on my 400... :o(

[470four]

Just took the bike for its first run of the year to the MOT station & back. 

Ride out was fine, smiles & giggles - bike was last ridden in November?

On collecting the bike from the MOT place (passed, no prob) I went to start it & - no sparks...plenty of fuel, kill switch on, fuse ok, all dash lights up, kill switch on, all plug leads & connections fine, kill switch on...

Pulled a plug out & no spark to be seen, tried the lead the other side & nothing? Bike has Boyer ignition, managed to avoid any rain etc - only upgrade recently untested was a new ignition switch?

This is where my suspicions lie... the old switch is too nasty to try as a spare - am I right in thinking if the switch is faulty you can have all lights working, starter motor etc - but no ignition system?   

Your thoughts please!   

[470four]

Have tested the killswitch - works fine, have good feed up to both coils (multimeter) but still no spark?   

[PatM]

That happened to me on my first run for a while- it was one of the fuses had desintergrated- rather than blown- i.e , the fuse looked perfect and I struggled to find some fag-paper to fix it (as I would have done in the old days) as Id given up. Anyway, something turned upon the road and got me home. I now smoke again..
Seriously, do you have 12 v to the points (with them open)? Thats where I would start.
Let me know and I add some more, step by step.
PatM

[Spitfire]

Had a similar one, went out for a ride, stopped at the daughters for a cuppa, went out to start the bike and it would not start, everything looked fine but in the end I found that the connections in the back of the fuse box were the problem, the fuses looked and were fine, it was the corroded wires behind causing the problems.

Cheers

Den

[470four]

Cheers peeps!

I picked up a VGC fusebox from the Bath & West, will drop that in in the morning and have a look...

Can somebody refresh my memory as to what all the fuses are please?


I have Boyer ignition - so No Points... & supposedly more reliable??    Lights all work ok?

There is a 12v feed off the battery + & - to the Boyer cleverbox anyways, so Im thinking there may be a feed to the coils without the ignition system on??

[470four]

Top and bottom fuses are spares, then 3 fuses for front lights, rear lights & main.

Have removed the entire fusebox & checked for continuity from the plug - all good (dammit), replaced the fusebox with another (checked) one in better condition regardless. 

The coils have no current going to them when the ignition is off, only when the ignition switch is on, so that rules out the ignition switch? Have continuity between both coils...

Im thinking its a fault from the Boyer blackbox, the "trigger", if you will?

Anybody?

[mick]

do you have anyone near you you could borrow points set up ?, at least if it ran you could save your self a lot of messing?

[470four]

Checked continuity of the blue & yellow wires from the crank plate up to the blackbox?

Nothing. Not a sausage on either??

Mildly relieved I'd found the problem I thought I could just run two good wires down and solve the problem. 

Worked my way back along the sleeve with the blue & yellow wires in and found this at the far end!



WTH??

Turns out my cute minimal alloy chainguard had allowed the chain to munch these wires... 

Soldered on another two wires to make the length back up and crimped on two more bullet connectors, bike started first push of the button...   

RESULT.

On a lighter note heres my 470/4 birthday cake my Missus got done for me for my birthday today!



Had to close my eyes cutting it tho, lol

Heres a shot of the back of the fuse holder for reference? may be handy for troubleshooting, etc...

[Spitfire]

Great result, and I like the cake, you're definately spoilt, I recognise the back of the fuse holder from when I had to clean up mine and re solder everything, but it's great that everythings worked out.

Cheers

Den

[470four]

Great result, and I like the cake, you're definately spoilt, I recognise the back of the fuse holder from when I had to clean up mine and re solder everything, but it's great that everythings worked out.

Cheers

Den

Mate - its always something daft when your bike plays up... 

Just couldnt work it out??!  Checked & rechecked EVERYTHING - in the end my

[K2-K6]

It's good that you found it without too much cost.

Multimeters, I don't know how you can do some stuff without them as you've said. I've got one with a bleep for continuity that's really good for checking integrity without any power on the circuit.

crank sensors and intermittent stuff's a bit harder though you can use "an old-silly-scope" for that.

[mick]

Nice one Cyril  glad you got it sorted.

[470four]

Nice one Cyril  glad you got it sorted.

Got to wait until Tuesday (March 1st) to tax it now.... Looks like a nice day at the mo, so I want to ride it into work - will try and do it online on Tues morning...

[PatM]

Glad to read that all ended well- I kicked myself when it happened to me- but simle when its something simple. I know the electronic ignition solves points-wear- but I had a 400 in the 80s and the black-box let me down. At least with points you can see and measure if theres a problem.
I nearly took my 400 out today but thought better of it- I shall jump on the nice warm Beemer tomorrow..yep, Im getting older..

[Yoshi823]

Ernie Bransden use to have his shop in Anerley in South London. He used to be a lecturer at Bromley Technical College, & so was in an ideal situation to be able to design his own ignition system. I too bought myself a complete setup for my much modified CB750F2, & when I thought that I had a fault with it I took it back to Ernie for him to have a look at. Before he even looked at it he did state that 99/100 it was due to bad connections going to & from the back box. What I hadn't realised was that when I had come off the 750 a week or so beforehand, the Rickman engine protectors had sliced through most of the blue or yellow wire taking the signal from the points housing to the black box. I didn't realise this until the bike started to cut out onto 2 cylinders.
What I would ask though is why your blue & yellow wires are going anywhere near to your drive chain when they should be joining the wiring loom by the connector sleeve by the back light switch wiring connectors?

Glad that you got it sorted though. One of my invaluable tools in my shed is a multimeter, amongst other tools...but I have an O'sillyscope as well, just for that time when you do need to look at signals to/from sensors.

I can also understand why you found it difficult to slice up your birthday cake...it made quite a picture. Thank you for sharing it with us...