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Hi guys,
On my ETZ250:
My contact breakers are opening at the correct time, but also closing too soon after TDC.Initially I realised the first problem was the ability for the bike to run backwards very easily and indeed sometimes doing so at idle without even stalling.
But the second problem because of this I later realised and this is that the points being closed for so long overheat the coil and cause issues with reliability there with the firing, and not too long before the bike is actually unusable.
If I set the gap to a much larger extent, then the points stay open for the rough 1/2 to 3/4 rotation of the crankshaft, but of course it is out of adjustable timing range then..
Other than electronic ignition, how would I be able to get around this? Is it possible the crankshaft is out of true? Could shims somehow be installed between the rotor and cam to counter this?
I have tried various contact breakers, rotors and stators, and also a couple of different (but good) original ETZ cams.
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My comments are somewhat after the event so you may have sorted it by now, but:
Regarding the crank not running true, if you remove the side cover and start the motor and look straight on at the end of the cam I would have thought that if the crankshaft was running so out of true as to be causing your problem, then you would be able to see the generator slip ring actually running out of true and also see carbon brushes jiggling about backwards and forwards in the holder.
I would also imagine that if the shaft was bent and the rotor was running out of true, it would cause a serious vibration and as there is not much clearance between the rotor and stator coils, there might be a sign of rubbing between the two.
I just wonder if there is some damage right at the end of the shaft where the points cam locates due to a previous owner riving off the rotor with the wrong extractor tool. If so then could it be that the cam is not seating properly?
Final thought, are the engine main bearings OK and not really worn on that side which might enable the shaft to flail about a bit!
Other than that, I’m stumped!
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Hi Andrew, the total run out was 0.65mm, which is obviously a little more than the maximum prescribed of 0.03mm. Problem was caused by incorrect installation of the crankshaft and that’s on me being silly.
It not only effected how the timing worked, but indeed gave a very visible wobble on the slipring connexion.
I have a replacement crankshaft (the other one had it’s own problems besides the imbalance, and will be installing it properly and patiently.
Big lesson learntfor the future.
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I installed a tezet ignition on my 251 ETZ and had a similar problem re backward running. This seemed to be due to limited adjustment of the sensor to the contact lump on the magnet wheel. It was not possible to achieve the 2mm btdc because the adjuster ran up against the securing stanchion and tdc had already passed ahead of the sensor! I’ve tried to upload some pictures of my solution which is to fix the sensor bracket to the stanchion with its clamping bolt. I will need to drill another hole in the ignition base to hold it properly in place so that the sensor does not move out of line or even foul the magnet wheel. It is now as close to the recommended position as possible. Fingers crossed when I eventually try it out!
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