Vintage Dirt Bike Q & A

Awfully noob question, but I only have one coil and cannot damage it in any way. I assume that the HT lead on the 1979 (1978 and 1980) coil simply un-screws and can be replaced i.e. there is a pointed pin in the coil onto which any modern HT cable can be screwed. Thanks.

_________________
Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF

I'm pretty sure the HT lead on these coils does not unscrew.

Apparently the '78-'79 CR250R coil (30500-360-003) is also used on all the CR125M and CR250M models. I've repaired a few I've gotten off eBay, and on one particularly bad one I tried twisting off the HT lead. After about a half turn it made a cracking noise, then the rubber lead jacket spun loosely inside the rubber seal (the inner conductor was still intact and connected). I epoxied it back in place and kept it as a spare.

Ray

_________________
'74 CR125M (175cc), '75 MR175, '82 RM250Z, '08 YZ250F, '14 Zero FX electric, '14 Zero MX electric, '18 Alta MXR electric

...so no way to replace the HT lead because it is bonded?

_________________
Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF

Yes, I think that's true. The outer gray plastic case may even have been cast around the HT lead. I'm looking at one now, and it appears the HT lead may join the coil winding at the far end of that 45mm protrusion on the bottom of the coil. It seems like a good design to me, with the HT lead very well supported and sealed.

For what it's worth... I've gotten a couple of these with no continuity between the plug cap and the white/blue input wire, and both were easily fixed by putting a new NGK cap on. It seems like the HT lead and its connection to the coil should be very reliable, but it can be tested by sticking a pin into the HT lead's center conductor near the sealing cap and taking a resistance reading to the white/blue wire (this one reads 10,800 ohms)

Ray

_________________
'74 CR125M (175cc), '75 MR175, '82 RM250Z, '08 YZ250F, '14 Zero FX electric, '14 Zero MX electric, '18 Alta MXR electric

Thanks for the tip. In a clear out tonight I found two coils that appear usable and one that was in very poor condition. I'll check the resistance...

_________________
Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF