cb500 four coil suppliers

[AshimotoK0]

That is a scary amount !!  I shall do some of the suggested checks over the weekend and failing that buy some of the M & P ones.  Thank you for your guidance and replies one and all.

Yes just be wary of low resistance coils though and as someone else  says if you must use low resistance ones make sure you fit a ballast resistor, but I assume this reduces the HT voltage somewhat. The low resistance coil ones are obviously getting away with less turns of wire by doubling the current and effectively producing a coil that is not continuously rated like the Honda one.

[Colonial-Clive (yindi)]

Ash they say a picture is worth a thousand words, well yours on coil rejuvenation is a book worth having. I will definitely  keep this for future reference.

[gtmdriver]

I think Ash was referring to the prices of genuine coils at D.S. not the pattern ones!

Fair enough, but my advice would still be to check the primary resistance of any coils that you buy before fitting them to the bike. Even quoted figures are not always true. I spent quite a while trying to find a set of 4ohm coils for my Moto Guzzi and had to return a couple of pairs of  '4ohm' coils before I got a pair that actually were as described.

[LesH]

Hi Y'all, me again.  Well, coils both read 4.4 ohms +/-.   New points reset, new condensers, retimed, everything back in place.  Now no spark from anything ?  I'm losing the will to live.  I've been back through past posts and think I've covered the same topics so would be grateful for guidance or failing that if anyone fancies a trip to Thames Ditton  (armed with experience of these things) where copious amounts of tea etc., could be supplied !!    

[Ashdowner]

I got 2 coils from Wemoto which were advertised as CB550K replacements for around £60 and they work perfectly with my DS electronic ignition.

[LesH]

The trouble is that I don't believe that the coils are the problem any longer.  In an earlier reply the coil rating was suggested as needing to be around the 4 to 5 ohm and I'm getting a reading of 4.4 ohms.  I admit to not being very clever with electrics but I do think things have progressed to another problem, like, I think I've got a short somewhere now !!     
At my age I just want to ride again, no time to tinker.  I'm prepared to cross palms with silver if required ? 

[AshimotoK0]

The trouble is that I don't believe that the coils are the problem any longer.  In an earlier reply the coil rating was suggested as needing to be around the 4 to 5 ohm and I'm getting a reading of 4.4 ohms.  I admit to not being very clever with electrics but I do think things have progressed to another problem, like, I think I've got a short somewhere now !!     
At my age I just want to ride again, no time to tinker.  I'm prepared to cross palms with silver if required ? 

May be the secondaries or the HT lead connections to them. They are notorious for fatiguing around the point where the lead leaves the coil 'cos the plastic cover becomes hard and brittle.

[Seabeowner]

Les, Just confirm that you have done hairygit's suggestion of running a + 12V direct to the coils. Or have checked that you are getting +12V (I assume you have a multimeter as you have measured the coils resistance) to the double bullet connector that supplies the coils. Should be the black/white wire on the CB500. The blue wire then goes from the coils to the CB pts for cyl 1-4 and the yellow for cyl 2-3.
You could even check the +12v with and without the coils connected. It should drop a little when the coils are connected as at least one set of points will be closed.

[LesH]

Hi Seabe, Sadly I don't have a multimeter but "collared" the boiler repair man who used his meter to check. (The coils were off the bike at the time).  I made a "buzz box" to check for continuity from the blue to the 1/4 points and ditto from yellow 2/3 which at that time was fine.  Put the coils back on, tank on etc., but had no spark from either set this time.   Checked again from blue and yellow and now makes no difference which side I get a buzz from everything so thought I must have a short circuit somewhere.
I confess, I've not done a direct +12v to coils but ?  Without the equipment I'm having to think of simple solutions which, I'm sure it only is, because it had been running and lost pulling power, faded but would restart before doing it all again.  So, looking in the Haines book for "loss of power" took me on this route.  (The fuel had been in the tank for about 8 or 9 months with added stabiliser but I topped up with about a gallon of fresh before draining it all out and replacing once more just in case stale fuel was my problem but as you can tell I trailed off in other directions).
Thank you for reading my tale of woe !!
PS You're right, "Hairygit's" comment about the kill switch went through my mind even though I rarely ever shut down using it but the sad thing is I can't get the screws undone without drilling them out.  (Don't you just hate crosshead screws ?). 
PPS  If I'm understanding correctly, I've just tried +12v directly from battery to the Bk/Wh coil wires (and neg to earth) and looked for spark at points which wasn't there !!  Uh!

[Rob.b (Rob Birkett - RIP)]

 the sad thing is I can't get the screws undone without drilling them out.  (Don't you just hate crosshead screws ?). 
[/quote]

Ah, I think I know something about this.  If its on a Jap bike and looks like a crosshead screw, its not. It's a JIS screw (Japanese Industry Standard) they are a different shape and our western screwdrivers will gimp those heads.  You can identify a JIS screw as has a little dimple on the head.  JIS screwdrivers are available on the internet.

Good luck with your electrics, i'm watching with interest.

Rob

[Seabeowner]

Les, Difficult without a meter. But when the ignition is on and the kill switch is on you could check that you have +12V at the black/white bullet connector that feeds the coils by carefully connecting a small wattage 12V bulb between this and the bike earth.

Be careful not to short the black/white to earth otherwise you will blow the fuse or fry the wiring!

Also when the points are open you should also have 12V on them. That is all the moving part, spring and insulated terminal. A bulb connected between here and the bike earth should also light, but not so bright as the current is passing first through the ignition coil. (your 4.4 ohms)

Indeed the screws once chewed are a b****r.  The original tool kit with the JIS driver with T bar would do them easy and such a simple tool.

[Chris400F]

The original tool kit with the JIS driver with T bar would do them easy and such a simple tool.

Have a look on sites like eBay or Amazon for JIS screwdrivers. They are well worth having.

[ST1100]

Have a look on sites like eBay or Amazon for JIS screwdrivers. They are well worth having.

Yep, also look for Vessel 980 Series MEGADORA "IMPACTA" SCREWDRIVERS...

[LesH]

Thank you one and all.
Plenty of things for me to play with there now !  Point noted about JIS screws (for future) but I might add that I've now drilled the "B's" out and replaced them with M5 Socket Heads and having separated the switch clamp you still can't seem to get at the kill switch/wiring.
Tomorrow I'll have a go at "Seabeowner's" other suggestions if and when I get the chance. 

[Chris400F]

Have a look on sites like eBay or Amazon for JIS screwdrivers. They are well worth having.

It also occurred to me that if you go looking at screwdrivers (or even if you don't) it would also be worth picking up a cheapish multimeter, to allow you to check things like presence of volts and continuity. Shouldn't cost too much and you then have it in your tool box for another day!