[jeffers100]

Hi to one and all,

I am looking for some advice and direction to try to cure a problem.
I have a 1974 CB250 K4. Last time out it lost its spark to left side plug. The right side is still working fine (I rode 40 miles home on one cylinder). The bike will start but runs only on r/h cylinder.

I have replaced both coils, condenser, plug cap. The plug sparks fine if I put it in the opposite side and test. The points look fine, no pitting or burning (I have re-dressed them with a bit of wet and dry paper and gapped them).
But still no spark in the left side.


Does anybody have any advice as to where to go from here?


Thanks

 

[cmonSTART]

With your left point closed are you getting 12 volts to the left coil?

 

[jeffers100]

I'll check tomorrow and let you know.

Cheers

Jeff

 

[jeffers100]

Hi,
I think I've fixed it.
I checked the voltage as you suggested, it was 11.6 in r/h coil, but only 3v in l/h coil which I took to mean that it was a bad connection rather than a failure of a component.
Went through all connections from points and it now works..

Thanks for the pointer

Jeff

 

[cmonSTART]

Such is life with a 40+ year old motorcycle.

Also watch the connections in the points housing - if they're sloppy they can ground against the cover and give you problems.

Good luck!

 

[Ray'ssporty1200]

Hello cmonSTART,

Same here by half! or something like that, When I bought a new Honda Scrambler 360 I did not need to be a mechanic, as long as I had it, it ran great, and for that I was and am glad, had it been otherwise, I may not have gotten back into motorcycles some 40 yrs later.

That having been said though, I am just as content with my pre-owned 91Sporty, I saw her on the Harley used bike net and liking what I saw, I went in the next day and put a C note on her to hold while I sold some stock, Thanks Verizon ! I leaned more about motorcycles by having to work on mine at times and figure things out, an ya know something? I still liked it a lot, sure the old gal needed work, when I got her from the dealer who never bothered to do even the simplest of things like topping off the electrolyte in the battery, putting in an ignition switch so the key could only be taken out in the off position, talking to others and finding out how to test for a leak at the intake manifold, how to tell if the stator is good and tracing a circuit. I tell ya, motorcycling is or can be much more than riding. I found out the hard way when you have an old dyna spark advance with flyweights, it must be properly greased every 2K miles, had I known it, I would have greased it, when it goes, ignition timing is gone an all you get is back-fire.BUT I learned what to do about it and how to avoid that sort of trouble. In short I have had 50,000 great miles in rides and only a small amount of trouble, I learned more about bike engines and had great rides so it is all good.