no spark?

[dysfoundation]

hey guys im new to the forum and i just recently bought a honda cb750k
i bought the bike from the guy fully aware it needed work.
the guy was working on the issue of not being able to get a spark so i wanted to see if anyone here coul help start me off on where to look.

so far i have traced 12v all the way to the ignition coils and from there it reads nothing..soo im guessiong its them..

but when i turn it on and prep the bike to start the left coil warms up while the right does nothing

[sgtslag]

Download the Factory Service Manual from the home page.  It will guide you through troubleshooting the coils.  Basically, take a resistance reading on the windings of the coils.  Most likely, one of them is open.  Check the spark plug wires for continuity, as well.  Pull the plugs, and see what they look like, check the gap, replace if necessary.  NGK are the best; NGK Iridium plugs require less voltage to spark -- around US $8 per plug, but they will last a very long time, and they fire much more consistently than regular plugs (smoother running, fewer emissions).

If you need to replace the coils, search the Internet for GM coils to replace the OEM's.  Supposedly much less money, and far more reliable than the OEM coils.  Make sure you get dual output coils, though.  Cheers!

[dysfoundation]

the spark plugs are brand new and the previous owner spliced new cables onto the existing ignition coils.

thinking of buying these coils
http://www.vintagecb750.com/parts/480/17-6810.jpg

there a dual output but it looks like its just the coil and no wiring

also if the coil is open is it unfixable or is a wire just not connected right.

sorry for all the questions guys

[TOOLS1]

Coils can not be repaired. I do not think those coils will work with stock point ing systems. Also you will need to fabricate mounting brackets for them. Vintage should have stock replacement coils.
TOOLS

[dysfoundation]

yea i saw them im gonna order them monday when i get paid.

i checked out all other ignition points and to my surprise the contact breaker plate is brand new! i was pretty happy to see this

[Re-run]

I took my stock coils into a honda shop once and they got nothing from them. The coils worked fine. So testing them is not always easy.
If wires were spliced on, while it can work, I would rather get new coils. I have heard about the gm coils but never found the right coil. You can use any dual fire coil though with your stock system that is 5 ohms primary resistance. You can go lower but the points will wear out much faster.
Otherwise you can buy new coils for abotu 35 each from partsnmore.com that are similar to stock with the wires attached. You can get some lower ohm coils like cb900 coils that need wires for the same price. If you get an electronic ignition, these would work fine.

[dysfoundation]

yea i have the stock botton start wired up it just seems to be the coils from all i can see
im going to buy the 34 oem ones from vintage that come with all the wires attached.
then ones i get this thing fired up ill start upgrading. is there anything else that can prevent a spark from happening besides the coils and the breaker plate, spark plugs and a battery?

i have all three service manuals so i know the check list of things that might fail but i was wondering if there might be other factors

[jamman18]

I got mine for a great price on ebay and they work great!

[dysfoundation]

i dont trust ebay with components, you never know how much they truely have been used

[jamman18]

The company I went through has a great rep so there were not any issues

[lcochran]

I've got 2 in a box, that i ordered off ebay that i ended up not needing.  If ya want them let me know.  My email is [e-mail].  I could ship them this friday if needed.

[dysfoundation]

man i wish you said that a day before lol, i ordered brand new ones from vintage..o well i hope to have them in by friday and if all goes well then ill be adding translucent red gas/hose lines =]