March 14, 20197 yr Author 12 hours ago, tshock250 said: Have you strobed it to see what the timing actually is? You know, thats one thing I havent done. Should have done that first really but.. New CDI arrived today.... Still the same! But while starting/running it, it began running as it should: Turned it off, restarted, and... Back to being *****. Kinda gone away from the idea of timing being out, mainly due to the cdi swap making naff-all difference. Weak spark maybe, but intermittent. So hooked the fluke up to the connector to the cdi, between the blue and dark blue wires from the source coil, had a good fiddle with the wiring & wires on the stator, no real change in resistance. 22 Ohm seems a bit low to me though, has anyone any resistance readings for these Kokusan stators? The spark does look a little orange. Ive been through all the connectors and stuff, everything checks out okay. Edited March 14, 20197 yr by 2smoke
March 14, 20197 yr Just another thought...my first bike was an early txt pro 200.. It had an issue where it too wouldn't rev out...after much fiddling a friend took a look and found the rubber flap that sits at the back of the fuel tank was not secured correctly and was intermittently blocking the air intake!
March 15, 20197 yr After all your testing of the electrics along with replacing most of it, The only thing electrical I can think of is a break in a wire. These are often very hard to find as they intermittently work don't work, (work when testing and not.when operating) is my experience I have had vapor lock on my bike. Took a bit to find, as it stopped revving out, and went all boggy at top end,. motor ran very hot (running lean). got stuck, got out of trouble and restarted it, ran ok, but trouble came back quite quickly, wouldn't rev out. Back home found the fuel line was only 2mm off the exhaust.and went up and down before going into carb. This "hump" allowed a vapor bubble to sit and restrict the fuel flow. Re routed it down under and up to carb inlet so any vapor will either go up through the carb, or back up into tank, also its away from exhaust. How is your air filter, I've had one get eaten by the bike, never found it. Bike coughed a few times then came right. That filter was old and must have been crumbly. Which makes me think of an air leak somewhere.that leans out your bike, but maybe only in certain conditions. check the inlet manifold seal, carb to manifold, base gasket, etc, ( pour heavy oil around it when not going well and see if there is any change. Good luck and let us know how you get on Cheers.
March 15, 20197 yr Does sound a bit weak,what colour does the plug come out?After what you've changed on the electrics it seems unlikely it's that.Do you know anyone with a similar bike you could swap parts with?
March 16, 20197 yr Author Plug looks ok Ive had in the post today, a 3rd CDI, and a rewound stator. Still the same. Airbox is off. Tried another coil too.. Christ this thing is testing my patience!
March 16, 20197 yr In relation to chat about main bearings above - There is a gallery in the transmission that basically catches oil "thrown" up by the gears rotating. it feeds this transmission oil into a gallery behind the LHS main bearing and between the seal behind the stator. Centrifugal force from the rotating main bearing forces this oil to lubricate the LHS main bearing and ejects it out through the little hole in the outside of the bearing (that lines up with a hole in the case) and back on top of the transmission sump plug. creating a lubricating system for the LHS Main Bearing. If the main bearing oil seal is shot, or if the hole in the bearing is not aligned with the hole in the case, it allows transmission oil to get into the crank and hence the smoke. If a LHS main bearing it is not set properly in the case, and is "rotating" under revs or load, the evacuation hole may be out of alignment "sometimes" and hence forcing tranny oil past the bearing seal, into the crank, and hence the smoke. This is pretty much why Gas Gas stopped using the magnesium cases. The maggy cases would heat up (and hence expand) much quicker than the steel main bearing, and they could "spin" in there housing if revvved hard in that little window between when the cases swelled as heated, and before the bearing caught up. Also check your flywheel key is not sheared. This can allow random ignition timing as the trigger point moves in relation to the crank angle. Edited March 16, 20197 yr by arnoux
March 17, 20197 yr Author So, curiosity got the better of me today and I took the cylinder off for a look... Seems strange as it wasnt burning loads of oil, but obviously something going on here. Ill order new seals, gaskets and main bearings tomorrow. And a swingarm bolt as I had to sacrifice it to get the shaft out! Hopefully once its back together it will be right, although Im not holding my breath!
March 18, 20197 yr Oil looks very black,looks like its sucked in dirty gearbox oil.Looks the wrong colour for 2 stroke oil.Whats the cylinder bore like,worth putting a piston in it as well while its apart.You deserve a bit of luck with it after the grief it's caused you
March 19, 20197 yr Author 11 hours ago, huski said: Oil looks very black,looks like its sucked in dirty gearbox oil.Looks the wrong colour for 2 stroke oil.Whats the cylinder bore like,worth putting a piston in it as well while its apart.You deserve a bit of luck with it after the grief it's caused you Looks that way, not sure if that was the true cause of the issue mind! The plating on the bore looks fine, as does the piston so Ive ordered some mains, seals & gaskets. Will rebuild it once they all arrive then see what happens. Hopefully good news
March 23, 20197 yr Author 17 hours ago, thall1 said: Don't let it beat you! i assume it's still the problem ? Yeah same as it was before. Really lost with it now..
March 23, 20197 yr I would be dropping it off at factory kev's, then picking it up when its fixed & go riding.
March 23, 20197 yr 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.
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