May 10, 201313 yr Just wondering if anyone can tell me if this looks like scoring on the piston or if it's just the oil dragging across the surface? Throttle got stuck wide open the other day. Kill switch wouldn't work so a friend put his hand over the exhaust to stall it. It seemed to run fine after this but after another 4 sections went back to the van, tried to start it again but it wouldn't go. Also some comments made about it looking a bit smokey. Spoke to my local shop would said get the exhaust off and have a look turning the engine over slowly.
May 10, 201313 yr Author How do I check the compression? It is just a case of kicking the bike over? If so then it feels the same as pre-incident. I've changed the plug as a matter of course. The old one looked like this. Haven't carried out maintenance before (or trials!!!!) so not sure if this is good or bad condition!
May 10, 201313 yr The piston looks fine, As he said does the thing spark. Leave the plug out, but in the cap. Ground it to the motor and kick to see spark. Always be careful not to start it on fire!
May 10, 201313 yr The piston looks fine, As he said does the thing spark. Leave the plug out, but in the cap. Ground it to the motor and kick to see spark. Always be careful not to start it on fire! piston looks fine to me too
May 10, 201313 yr Nowt wrong with your piston mate. Silly question but is kill switch stick in? For what it costs if put another plug in to start
May 11, 201313 yr Sometimes after a stuck throttle overrev the woodruff key on the flywheel will shear. You will have spark, just at the incorrect time so it will not restart. Flywheel puller next!
May 11, 201313 yr Metal transfer is very obvious and I cannot see any on your skirt I think your top end is fine Engine failure does not explain your no start problem, maybe that keyway that Copemech mentioned You may be able to see the keyway on both the crank and flywheel after you remove the nut
May 11, 201313 yr Piston looks fine, rings maybe not going off the evidence of blowby below the bottom rings at the sides. Sometimes the rings lose their tension after a major hot moment such as a bike lying on its side revving until it starves of fuel, can remember NZ's top rider's 315 being like that when he first started riding due that happening lots in his first season What age is the bike, could be due them by now Agree that the key will be the issue, doesn't happen very often but the symptoms match
May 11, 201313 yr I can tell this is not a new bike, as the bolts for the pipe are verticle. Piston looks good and bike did not sieze, reports compression on kicker feels normal. No report of excess rattle after. Exhaust port is clean as well, no excess carbon build, so me thinks this a gently ridden bike on pure synthetic oil. A bit of ring blow is to be expected, tarnishing the sides of piston, no excess on yours.
May 11, 201313 yr I would be checking the ignition for a good spark and then the timing.Piston looks fine,good job it didn't seize up,would have been a lot of money
May 11, 201313 yr blimy i wish my piston and plug looked as good as them.. i ve got worse in boxes saved for a rainy day..
May 12, 201313 yr I should add: Wash the damn thing after your ride!!!!!!!!! Before you rip it down!!!!!!!
May 12, 201313 yr Author Copemech Agreed! I felt guilty after taking the pics but couldn't resist a quick inspection before cleaning it. It's sparkling now! Anyway...fitted a new plug, put it back together and......started second kick from cold (as always)! Glad it's running, BUT...I don't know if its just me but it does feel a bit more 'vibey' when ticking over and I thought I heard a very occasional metal 'knock' from the engine when warm and revving it hard. I'm fully aware this could just be me looking for something that's not there but is there anything else that's worth checking i.e. the carb?
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