Stuck in gear?

[Jacko]

Seems a bit minor considering what you've just completed, niggley all the same. Has the C12 disappeared now?

[mjc506]

Yeah, it's small stuff, but annoying if I have to hotwire the bike each time it rains

There is no FI error at the moment (the bike is dry) and while the engine is running there's no issues.

I'm thinking worst case - some crap on the CKPS itself (entirely possible, it has just been rebuilt. In a garden...) giving a weak signal until the engine turns over, then it's cleaned off with oil. Or maybe just dirty connections (more likely, as the bike appears to be fine when dry, not fine when wet... but that doesn't explain why the bike runs fine once it's going? Perhaps there's enough signal there to run, but the ECM is more picky on startup?). In either case, the engine should still turn over, if not start. But it doesn't, so something's up there.

Can the ECM stop the bike turning over/starter running? Looks from the wiring diagram that it's possible, but also that the solenoid shouldn't click if that's the case. Wouldn't be inconcevable that both the CKPS and starter solenoid have issues.

[greywolf]

Your most likely problem is a connection on one of the large battery cables at either end of the cable or between solenoid and starter motor. The ECM isn't going to stop the starter motor when the solenoid is shorted. A marginal connection can cause FI errors by dropping the voltage to a sensor out of range.

[user650]

Sounds like bad earth or corroded lead some where, do you know how to do a volt drop test?

Using a volt meter set to handle 12 volts connect in parallel with the wire or part you suspect. There should be no more than half a volt reading MAX

e.g connect to bat positive and starter pos connector, try to start and check reading if no reading check the earth side I.e bat neg to starter case

hope you can make sense of this

[greywolf]

A voltmeter may not detect a marginal connection. It can look fine with no load but fail when a working load is applied and the starter is a very big load.

[user650]

Any marginal connections should show up on voltmeter when trying to start, even if the bike starts readings above half a volt indicate a  resistance. Placing the voltmeter in parallel with any wire and loading that circuit should show connect ion faults

edit

I've found a PDF file that explains it better if you need it

[mjc506]

Sorry, none of the above replies flagged this topic as 'unread' to me

As it's been dry for ages, the bike has been starting fine with no issues, so I've not had a chance to really troubleshoot. A voltage drop test was one of the first things I done, but I could find no problems.

This morning however, was a little damp... and the bike refused to start. Same symptoms. Unfortunately, I was late for work, so decided just to get it running rather than do a full diag.

Top box off, seat off, 'special tool' (length of wire) ready... first, I try shorting the solenoid (it's raining, and I don't really want to kneel under the bike to reach the starter)... a few sparks, not much else, until my little boy shouts "smoke!" Huh? he's pointing at the starter, and the 'smoke' is just a wisp of steam. I try again, looking at the starter... a few sparks from the wire, and yes - definitely some steam coming from the connection to the starter motor! A closer look reveals the water around the connection boiling, and a nice purple glow radiating from the connection. That'll be the problem then (I thought 12V shouldn't discharge like that?) I jump the bike again (battery +ve direct to the starter motor) and it starts fine.

Now at work, I have a better look. The bike dried off on the way, but has since sat in the carpark having a 'wash', so is wet again. I'm still getting that corona discharge around the connection. Could be a marginal connection plus salt doing that. It's pretty, but obviously not optimal No time to do much more at the moment, but I'll have a proper look once I'm home

[Jacko]

Sounds a right PITA.

[mjc506]

nah, it's an anti-theft device (when wet) at least it doesn't stop the bike running.

[MartinW]

Really useful those little kids who point out things too far down and round for us grown ups to see.

[mjc506]

Yup, I'd never have seen it myself. He's earned himself a bag of sweets tonight

[mjc506]

It appears to be fixed

Took the starter motor connection off the other night, and found it coated in a nice protective salt film Cleaned it all off (tesco value coke is fantastic for this sort of thing - not too aggressive unlike 'real' coke) dried up, put it all back together...

After a few more days of rain and wet, everything seems perfect

[Jacko]

Excellent. Are you going to add your lad to the 'specialist tools' list?

[mjc506]

I imagine his mother would object to him being rented out

[MartinW]

He will be fine. The rules state that everything has to be returned in the condition in which it was loaned.

[Juvecu]

[Ambergnat]

Wow! - just read this from beginning to end.

Outstanding engine rebuild sir, and as well documented as ever I have seen one.  I pray that I never have to do anything as drastic to mine

[mjc506]

Well, it's still running, so I can't have done too much wrong!

There's still very few Wee engines that have needed rebuilding, so there's excellent chances you'll never have to see some of these bits first hand