Possible CDI fault
 

Hello,

I’ve got a 1986 Yamaha XT600 (43f) and I’ve been having some ignition issues with it.

I’ve replaced the ignition coil to no avail, and now have moved on to checking my source and pick-up coil resistances. My source coil is reading 159 ohms, and my pick-up coil is reading 232 ohms. According to my manual (Clymer) the source coil should be reading between 160-240 ohms - so I think that’s functioning okay, be it a tad on the low side. But my pick-up coil is meant to be between 90-129 ohms… obviously my reading of 232 ohms is a lot higher. My main query is whether this would cause the problems as follows:

1) Cold starting has started to be more difficult and when it has started it’s missed a few fires and almost cuts out before warming up a little bit. After it’s warmed up is ran very well.

2) The first major problem started when I was riding on the motorway (doing about 55mph so fairly steady) for about an hour before the bike completely cut out - didn’t bog or sound like it had carb problems so I assumed it was electrical. I couldn’t get it going again so left it for about 10 minutes to cool off before trying to start it again. When I tried again it started perfectly and ran well, so I continued on the motorway for another 20 minutes before it did the same thing, except this time it fired up straight away again.
After another 20-30 mins driving a lot slower (trying to limp it home) it cut out once and for all and wouldn’t start again.

3) Since then, I’ve had it sitting and have managed to get it going, but quickly miss fires or dies. I’ve blown out the carb and made sure she’s getting fuel but it hasn’t made a difference.

After going through the manual and finding the suggested pick-up resistances and finding mine to be a lot higher, I’m thinking this could be the problem… I would be very interested and grateful for any input or suggestions, do the symptoms I’ve described sound like the pick-up is faulty?

open your own thread, post a pic of the bike (we love early 600's) and then we'll talk.... c'mon, dont be shy, no need to hide in non-functional member's threads

Post moved to new thread.

Now, who can help this poor guy out?

It DOES sound to me like he's on the right track. Personally I'd try a new pickup, but I'm not an XT guy so could be way off.

well, bike is not usable but guy hasnt checked for replies in two days... whatever....


From my experience it's the magneto power coil on his way out, seen these fail much more than the pickup... they work a bit intermittently, then finally die :P



in any case, picks-up are cheap, so change it to be sure its not that,



the power coil is inside the stator, therefore is very expensive to replace


ignitech.cz does a cdi that doesnt use the power coil (uses instead the bike's 12V system), drop them an email

Yep agreed, soon as that oil gets hot he has the problem.

Mezo.

CDI
 

Okay - update, I've now tested my stator properly. I've read on other threads that the Clymer manual gives the wrong measuring instructions and therefore suggests incorrect limits for resistance values for the pick-up coil and source coil. Apparently, according to the OEM manual the resistance I'm getting are fine. I've also heat check it by putting in the over and the resistance numbers are pretty stable.

This has led me down the CDI route - not ideal as they seem to be very expensive and I can't be interlay sure whether that's the problem. looking into getting one now from Zeeltronics.

Any suggestions and thoughts would be greatly appreciated!

Okay, I've now installed a new CDI from zeeltronics - spark seems to be stronger however the bike is still as dead as a doornail. I know fuel is getting to the cylinder because after 5 mins of kicking it over, messing around with the choke etc.. the spark plug was wet with fuel.

I can't think why the bike isn't firing whatsoever. Can't test to see whether the new CDI has actually solved the original problem either.

Could valve timing be my problem? seems weird as the bike was running fine and then died. (as explained earlier in the thread).

Again, any suggestions would be appreciated.

Changed spark plugs a few times - doesn't make a difference sadly!

valve timing cant jump just out of the blue with engine assembled.


so you went from "hard starting" to "no starting" with this new CDI swap, but you do have spark?


so the timing I would try to check at this point is of the ignition with a timing gun and degree wheel.


would also try to swap the wires coming from the pickup to the CDI,

Yes - before with the old CDI it would fix up (hard start be it that) tick over for about 20 seconds and then just die. If I tried to rev it would also die.

With the new CDI I'm getting a better spark but I can't get it going whatsoever.

Does seem like a timing issue, and as you say, perhaps I should swap the pickup wires. only problem is - the cdi has a nice plug for the pickup wires, so hacking it up and swapping them might be difficult. is this something people have had problems with before with the zeeltronic cdi?

"people?" :) :)
lately there's about 2.5 guys with good technical know how that post here regularly...


how much of a chance that they have "zeeltronic timing issues" experience you think there is? :innocent::innocent::innocent:



i dealt before with ignitech.cz aftermarket CDI guys and they were sort of suportive, did you try contacting zeeltronic? understand your reluctance to split their plug...



in any case, could be helpful to check the ignition timing as i suggested to know where you stand



you might have better luck in the ADVrider forum/xt600 section, it's quite a bit more active than this one, (with all due respect to HU pioneers, etc...)