March 23, 20197 yr Author 4 hours ago, mcman56 said: I can mention a couple of hard to find ignition issues I have encountered and a diagnostic idea. A friends Beta recently quit running. It would sort of start and die. I checked the carb. And then looked at wires. The power wire to the coil had a little cut in the insulation like someone screwed up when installing the connector. There were some signs of arcing. It got taped up but it was not the issue. I unplugged the kill switch and it was the same but I noticed a flickering light inside the connector on the bike side of the wiring when kicking/ running. I broke the connector open and found the two pins burnt due to arcing. I replaced the connector and all was good. I don't know how I would have found that without seeing the arcing. I never would have suspected something inside the connector of the main wiring harness. A continuity check at that connector could be a good idea but if it is intermittent may not be found. I had a little kids bike that would start and run fine but start to miss under heavy load. I found a bare wire under the flywheel. It was not touching so worked OK until the voltage got high enough and jumped the gap. It is not easy but If you have access to a lathe or mill, it is possible to set up the ignition system on that and run it off the bike. A drill press may work too. The stator needs to be properly positioned in the flywheel. (not much clearance to play with) Plug in CDI, coil and spark plug. Ground the side of the plug and use the machine to spin the flywheel. You can observe performance and a timing light can be used to look for consistent timing. If you mark the flywheel and stator to identify some degrees before center, you can see if timing is close. I like that thinking. Ive got a mill & lathe, so could knock something up to test it with. Have got a few options now Ive calmed down, keen to buy another bike just for diagnostic purposes to help with tracking down the problem!
April 8, 20197 yr Author On 4/6/2019 at 7:47 PM, thall1 said: did you get it sorted? No, it's back in the corner of the garage. Can't waste any more time/money on it at the moment!
April 14, 20206 yr Author Well a year later, and on lockdown so decided to drag it out of its hole and try again! Cleaned the carb out, drained the tank, stuck some fresh fuel in and started up. Ran well for a bit, had a couple of rides round the garden but wasn't convinced! Started playing up again, same symptoms, coughing and banging, exhaust temp through the roof (actually melted the clutch hose!) Then turn it off, start again and running fine. It's bloody cursed I tell thee!
April 14, 20206 yr hi not a wind up ! check flywheel magnets --- had bikes run ok but higher revs no chance what happens its a weak magnet that do not but out enough current to send the cdi into advance All i do is hold a small screw driver to the inside of fly wheel feel it getting pulled by magnets as you move around the inside of the flywheel with luck you will feel a weak one and theres the problem hope this helps
April 14, 20206 yr Author 32 minutes ago, on it said: hi not a wind up ! check flywheel magnets --- had bikes run ok but higher revs no chance what happens its a weak magnet that do not but out enough current to send the cdi into advance All i do is hold a small screw driver to the inside of fly wheel feel it getting pulled by magnets as you move around the inside of the flywheel with luck you will feel a weak one and theres the problem hope this helps Never heard of that before, but I am running out of straws to clutch at! Will give it a go later cheers!
April 14, 20206 yr Author 21 minutes ago, huski said: Have you tried another stator? Yeah. A freshly rewound one that was working on another bike. Along with 4 cdi's, 3 coils etc. The only thing I've not changed on the ignition side is the flywheel itself..
April 14, 20206 yr Try a different flywheel perhaps?Are all the connectors on the wiring good?I feel it's got to be electrical,a mechanical problem would always be there.Seems like as soon as something gets hot enough the resistance increases to a point where it no longer works properly
April 14, 20206 yr Author 8 minutes ago, huski said: Try a different flywheel perhaps?Are all the connectors on the wiring good?I feel it's got to be electrical,a mechanical problem would always be there.Seems like as soon as something gets hot enough the resistance increases to a point where it no longer works properly Electrical was my thought too. I've been through everything else really, con checked all the wiring, resistances checked hot and cold. Put the megger on the earth points etc. I'll get the flywheel off tonight for a looksie again, see if there's anything I've missed.
April 15, 20206 yr Author Took the flywheel off last night, nothing amiss really. Magnets all seemed the have similar strength. Did notice some play though between the keyway & woodruff key. Not sure if there was enough to cause this issue once tightened but have ordered a new one anyway. It would be ironic if it was that all along.. Does anyone know at which point btdc the ignition fires?
April 15, 20206 yr 9 minutes ago, 2smoke said: Took the flywheel off last night, nothing amiss really. Magnets all seemed the have similar strength. Did notice some play though between the keyway & woodruff key. Not sure if there was enough to cause this issue once tightened but have ordered a new one anyway. It would be ironic if it was that all along.. Does anyone know at which point btdc the ignition fires? The woodruff key is purely an aid to locating the flywheel correctly and plays no part thereafter.
April 15, 20206 yr Author 1 hour ago, b40rt said: The woodruff key is purely an aid to locating the flywheel correctly and plays no part thereafter. Thanks I understand that, but with the flywheel fitted (& woodruff key in place) there was still a bit of play when rotating the flywheel slightly, like the key in the keyway was a bit slack. This is without the bolt fitted but the flywheel tight against the taper.
April 17, 20206 yr Author 22 hours ago, guy53 said: Are all the flywheel the same ? Guy Not sure Guy, trying to find out the differences atm!
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