dmx84 Posted February 15, 2012 Report Share Posted February 15, 2012 Here's what happened, maybe someone has had a similar problem.... I was cursing up a mountain road (top gear/mid-high throttle) and when I started to slow down it acted like it was starving for fuel. When I dropped into a lower gear it acted fine at the higher RPM's, but once the RPMs got low it started to die (again sound like it was starving for fuel. I pulled off the road and checked the fuel and it was fine, but wouldn't start this was the last time it has ran. I rebuilt the carb thinking it was a clogged jet or something. I replaced the plug & have a spark but it looks a bit weak to me and will only start after lots of kicking. Once it starts it will start to rev up high for only a few seconds and die. Does this sound like one of the symptoms of a bad stator? One of my friends thinks it could be the trigger? (because it fires when kicked fast) Is there anyway to check the stator with a meter to verify if it's good or bad? Thanks, Dean Quote Link to comment Share on other sites More sharing options...
dadof2 Posted February 15, 2012 Report Share Posted February 15, 2012 As the rpm drops, the voltage / current to the cdi drops so if there is a fault with the cdi charging coil meaning it is giving less than its intended output this will be more prevalent at low revs. Trigger coils usually work or they don't but they can show the same symptoms. I would expect the cdi charging coil to have a resistance of 50 to 250 ohms (unfortunately BETA in UK don't publish the exact values) Trigger coil resitance can be similar or even up to 1250 ohms. Digital multimeter needed The problem with the above is that resistance and generating capacity vary with temperature. The best way to check is with an oscilloscope whilst rotating the engine with a power drill. Any deviatin from a smoothe / expected waveform indicates a defect. It would be worth taking the barrel off to check the piston has not scuffed slightly and nipped a ring, this alo gives symptoms you describe. Cheers Quote Link to comment Share on other sites More sharing options...
fatbastard Posted February 15, 2012 Report Share Posted February 15, 2012 We have had a dodgy kill switch giving similar symptoms. Is it the original kill switch, I know some dealers are fitting after market ones to brand new bikes as the problem is that common. Quote Link to comment Share on other sites More sharing options...
naichuff Posted February 15, 2012 Report Share Posted February 15, 2012 My 03 Rev3 200 also did this I blamed the deep water in the first section but failed completely at the furthest out point and at the bottom of the hill On return to workshop it was a stator failure that was the second one It would start when cold then slowly died the Cdi coil braking down Quote Link to comment Share on other sites More sharing options...
jcam Posted February 15, 2012 Report Share Posted February 15, 2012 same problem on 2002 rev3, it was stator faliure. Quote Link to comment Share on other sites More sharing options...
dmx84 Posted February 16, 2012 Author Report Share Posted February 16, 2012 My 03 Rev3 200 also did this I blamed the deep water in the first section but failed completely at the furthest out point and at the bottom of the hill On return to workshop it was a stator failure that was the second one It would start when cold then slowly died the Cdi coil braking down Did the stator fix your problem (x2) then the CDI failed? same problem on 2002 rev3, it was stator faliure. Who is the best place to get the stator? Quote Link to comment Share on other sites More sharing options...
dmx84 Posted February 16, 2012 Author Report Share Posted February 16, 2012 As the rpm drops, the voltage / current to the cdi drops so if there is a fault with the cdi charging coil meaning it is giving less than its intended output this will be more prevalent at low revs. Trigger coils usually work or they don't but they can show the same symptoms. I would expect the cdi charging coil to have a resistance of 50 to 250 ohms (unfortunately BETA in UK don't publish the exact values) Trigger coil resitance can be similar or even up to 1250 ohms. Digital multimeter needed The problem with the above is that resistance and generating capacity vary with temperature. The best way to check is with an oscilloscope whilst rotating the engine with a power drill. Any deviatin from a smoothe / expected waveform indicates a defect. It would be worth taking the barrel off to check the piston has not scuffed slightly and nipped a ring, this alo gives symptoms you describe. Cheers We have had a dodgy kill switch giving similar symptoms. Is it the original kill switch, I know some dealers are fitting after market ones to brand new bikes as the problem is that common. I'll get a o'scope and check this out before I tear into it. I can also test/eliminate the kill switch at the same time. You think the o'scope can see anything with the CDI? Quote Link to comment Share on other sites More sharing options...
naichuff Posted February 16, 2012 Report Share Posted February 16, 2012 NO just got the stator rewound bike fine ever since Quote Link to comment Share on other sites More sharing options...
dadof2 Posted February 16, 2012 Report Share Posted February 16, 2012 Unless you have easy access to a scope I would just check the CDI charging coil on the stator with a digital multimeter first. 9 times out of 10 this is the cause of Beta stator / ignition failure. As well as resitance quoted previously I would expect this coil to have an output of 20 to 30 volts AC if flywheel is rotated at about 450 to 650 RPM with a drill. If you have a friend with a running Beta with same ignition system check that to see what it should be. Regarding scoping the CDI theres not much you can do without very specialised pulse generating equipoment and manufacturers info. The one thing you can check is the CDI to coil output ONCE you know your stator output is OK and therefore charging the CDI, Spin the engine with drill and the CDI to coil output probably starts at 350 volts dropping to near 0 volts over 200 to 250 miliiseconds. Again doing the test on a known good bike would give you the exact voltage curve you should see on the scope. A 4 channel scope with trigger so you can measure A V in and A V out simultaneously is most likely to give really useful data. Cheers Quote Link to comment Share on other sites More sharing options...
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