poor spark on left spark plug

[bobthebiker]

hey y'all.  I need a little help here.  I have been trying to get my bike to run well for a few days, right now I have a not so strong or hot spark on the left coil, its like intermittent,  and an orange like weak spark on the right coil.   

is this plug wires? or ignition coils going bad on me?   I know it isnt plugs because I've got like 3 sets of brand new ones right here.   all connections are firm and clean, particularly going into the CDI box, which was my first check, followed by the wires going to the right side of hte bike where the ignition triggers are.  all wiring is fine,  the plug going into the CDI had some corrosion from battery acid leaking onto it(thanks previous owner)  which I cleaned off, and it helped a little.  from here I dont know where to go though.

[Kerry]

If you have an ohmmeter, check the resistance values for both the ignition coils (see [THIS POST]) and the signal generator coils and associated wiring (start [HERE] and read to the end of the page).

Here's a set of pictures that show what I ended up having to do because of "some corrosion from battery acid leaking onto" a connector in that area.  (But don't do anything this drastic until you've worked through that page!)



I originally bypassed just the one connection that was "shot".  Later, I replaced the entire connector with the four individual pink connectors in the photo below.

[bobthebiker]

On my connetor, I figured out how to remove each individual connector, clean it and put it back. 

I need a volt ohm meter to find out what's good and whats not on my bike. at this point I've got lots of crap to figure out, no idea where to start, and I"m starting to want a newer bike.

[The Buddha]

Also check the auxillary ground.
BTW, can also be a bad spark plug.
Cool.
Srinath.

[Kerry]

On my connetor, I figured out how to remove each individual connector, clean it and put it back.

Good job ... that's something I didn't even try!    I did try to pull the connector apart, and started breaking pieces off of it with no success.  It must have been corroded pretty good inside.

I need a volt ohm meter to find out what's good and whats not on my bike. at this point I've got lots of crap to figure out, no idea where to start, and I"m starting to want a newer bike.

Yep; as I think you're saying yourself, you need to make sure that the connection all the way through the connectors are clean.  (No ... or low ... resistance.)

There are a couple of ways to do this.  One option is to use a dedicated continuity tester like these:


A dedicated continuity tester can be great for quick checks, but it can only answer the question: "Is current flowing through this circuit or not?"  It can't tell you the amount of voltage or current or resistance for a circuit.  This would be fine for checking your wires and connectors in this particular case, but ...

... a better option is to use the lowest Ohms setting (or the continuity setting) on a multimeter.  If I had to choose, I would pick an inexpensive digital multimeter over a continuity tester every time.  They're so much more versatile ... they allow you to verify all kinds of stuff against values listed in service manuals, etc.  It looks like both [HOME DEPOT] and [SEARS] have decent models for $20.  Want something smaller that you can take along on the bike?  Check out [THIS] $20 Sears model.  It even has auto-ranging, so you don't have to pick between multiple ranges for a given function.  Think about it ... $20 now will get you a handy unit that you can use on vehicles and in your home and shop for YEARS to come.

Whatever you do, don't give up just yet.  I know it can be frustrating; that little "corrosion episode" on my bike took me 5 months of (infrequent) testing to figure out.  Waiting at the end of it all was the "Duh!  Why didn't I see that connector?"

It sounds like you're pretty close to finding the problem on your bike too.  With a little extra "verification" we can eliminate some possibilities without the hassle of involving dealers (either for service or for a new bike) ... just yet.

[Wanna talk through this?  PM me for my phone number.  I'm taking most of the rest of the week off, although I may not be at home the whole time.]

[bobthebiker]

as soon as I can, I"m going to borrow a friends multimeter, and test the whole ignition circuit from CDI to plug.   

I realized all too late that you can order new plug wires separately from the coils, but this was after I bought a new set of coils(which MAY be useful) to use. 

being the bike IS 20 years old almost, its likely just a bad plug wire or two coming from the coil to the plug.  but it never hurts to be POSITIVE nothing else is wrong as well.

[Kerry]

as soon as I can, I"m going to borrow a friends multimeter, and test the whole ignition circuit from CDI to plug.

Sounds great!  While you're at it, you may as well check the charging system too ... to make sure the battery/alternator combo is putting out enough juice for the ignition system.  (I'll try to update the "HOW TO" to reflect reality when it comes to the regulator/rectifier.)

I realized all too late that you can order new plug wires separately from the coils, but this was after I bought a new set of coils(which MAY be useful) to use.

Ouch!  Sounds like one of those times when a $20 meter (and some resistance values from a $25 manual) would have already put you money ahead ... IF your original coils and plug wires turn out to be OK.  I'm one to talk -- I picked up a new regulator/rectifier before discovering that I had used the wrong test procedure on my perfectly fine R/R unit.  (OK, I was lucky ... I got a used one, for free.  But still! )

[...]it never hurts to be POSITIVE nothing else is wrong[...]

Well put! 

[bobthebiker]

on the coils,  the second set that I"ve got on the way, in my view, is spares.  one of those, I have em if I need em, or someone else does kind of deals.

[Kerry]

Sorry - I didn't mean to sound like I was scolding.  The little guy was for ME. This was one of those cases where I would have been OK if I had only followed my own advice ... about checking both Haynes and Clymer for a new-to-me procedure.

Happy Trails!

[bobthebiker]

its all good. my initial thought, before thinking to check the primary and secondary windings was that my coils were going bad, so I ordered a new set.  I dont doubt the plug wires are probably junk after 20 years.

[desilva]

Did the new coils fix the problem?