Coil question

[leezzr600]

Hello

Having some brain ache getting my missus's 91 L to start

Having tested the :smt013 out of the ignition system, i'm leaning towards carb issues.

But one thing is bugging me, having never seen what a "good" spark should look like , I'm almost convinced I might have a weak spark

so i've checked as per the manuals

coils, resistance checks ok (primary and secondary contacts)
HT leads, resistance checks ok, (good connections to plug caps)
new plugs (cr9ek's)
new battery
CDI resistance table (managed to get all the right figures)
main earth is clean and tight
12V to both red leads for the coils

the only thing I can I think might be an issue , is when I hit the starter button the voltage on both the red leads drops from 12v to around 9v , is that normal , i assume thats just the load? or should I see 12V all the time?

[RedexRobB]

A good spark should nice n blue, a weak one will be yellow.

After trying to start, it could be worth looking at the plugs, see if they are wet. This will give you an indication that fuel is getting through. You may find the voltage drops because the coils is being switch on and off as the engine turns, as an average this might look like 9 volts to the multimeter.

Have you tried using the choke? And as always, is the battery well charged? Weve seen it before where what appears to be a good battery, actally needs renewing or a long slow charge.

[leezzr600]

its a blue spark not yellow

I thought that the green and the black wires did the switching on/off for the coils? the reds were constant 12v?

I'll try another battery just in case, tried with and with out choke , doesnt seem to make much difference

Will see if i have wet plugs or not...

[leezzr600]

also jump starting off a car didnt help , surely that would discount a battery issue?

[Mori Man]

Scoosh some easy start down the the throttle bodies with the airbox off - I am sure it works by just removing the airfilter and spraying away while trying to start the bike.

With the tank off use a decent size jam jar full of fuel and place down near the pump - this will show you fuel being sucked up and delivered to the carbs and give you a chance of spraying the easy start.

If you don't get any responce from that then your in soapy bubble ! The stuff is exremely volatile so even a weak spark will set it off , your next option would be valve timing and or valve gaps.

MM!

[leezzr600]

Dry plugs :smt013

[Mori Man]

Try the jam jar and see if your fuel pump is working - when I plugged mine all back together I had put the hoses the wrong way round

[leezzr600]

pump is good, the jam jar is full!!

off to clean the carbs

[leezzr600]

Carbs cleaned , still no joy , taken the head cover off, looks like the timing is one tooth out :smt013 .

More fun and games....

[Mori Man]

Forgot to ask , did you buy this as a non-runner ?

How did it get from being a running bike to this state if not ?

1 tooth shouldn't be enough to cause this problem but if timing is 180' out it will never start in a month of Sundays.

[leezzr600]

was a non-runner when I got it, yes. Head gasket had gone.

Is it possible for the camchain to jump teeth on these? My father had this happen to him on his honda VTR , the tensioners on those aren't the most reliable.

[leezzr600]

Forgot to ask , did you buy this as a non-runner ?

How did it get from being a running bike to this state if not ?

1 tooth shouldn't be enough to cause this problem but if timing is 180' out it will never start in a month of Sundays.

with the two camshafts lined up on the top of the block, the ignition rotor the T F end is a tooth too far round past the mark (clockwise)

if that makes sense?

[Mori Man]

Ah , so the cams have been taken out and put back in.

I would check they are in the correct sequence - it's easy to set them 180' out if your not careful.

Check the workshop manual and identify the cycle is TDC for #1 cylinder and that the cams are in the right way.

It is possible for any bike to jump teeth with worn tensioner or chain - depends on mileage and abuse.

MM!

You can run a lot of Kwak engines slightly advanced so I don't see that being the issue but best to reset so everything is as should be and help identify whats going wrong.

[leezzr600]

This might sound stupid , but how would you know if you are 180 deg out ? #1 and #4 TDC is at the same place no?

[Mori Man]

It's to check they havent been put in on the 2nd timing mark on pulsar.

#1 TDC the pulsar stamped number is right way up and the notches on the end of the cams point away from each other and the timing marks on the cam sprockets.

Spin it 180' and the pulsar number is upside down or on its side (been a while since I looked) , the cam notches point towards each other as do the marks on the cam sprockets. At this setting it is possible to remove the cams and set them as above making the ignition to valve opening timing 180' out.

I don't have cams handy but if the cam sprockets are removeable is it possible to fit the sprocket with the timing mark out ? Effectively doing the same thing of timing the cams 180' out.

I was for ever doing this on my CG125 - for some reason it was a lot easier not to notice with the push rod engine. It only took me a half dozen kicks to suss I had done it and 30mins to rectify and off it would go on 1st kick again. The very first time it happened after a re-build I was chasing ghosts for three days doing exactly what your doing, to save torching the bike I started from the begining again re-tracing my steps so that meant doing the valve timing and hey presto there lay the problem.