jkkl Posted February 4, 2010 Share Posted February 4, 2010 i have a 92 sr125 which will bump start easily but wont start on the starter. it has a new battery fiited.it has stood unused for 6 years. i have cleaned out the petrol tank, tap, and carb it occasionly fires on the starter but wont pick up. another day you go to it and it starts instantly on the button. when it is idling sometimes it just cuts out suddenly and then wont restart unless bumped. i have renewed the air filter reground the valves checked the rings were'nt stuck on the piston, the bore is like new. it has good suction on the inlet manifold. it also seems to have a spark when not starting.the bike has done 7000 miles from new.i have also sprayed wd40 on every connection i could find. Link to comment Share on other sites More sharing options...
2 Wheels Posted February 4, 2010 Share Posted February 4, 2010 i have a 92 sr125 which will bump start easily but wont start on the starter. it has a new battery.it has stood unused for 6 years. i have cleaned out the petrol tank, tap, and carb it occasionly fires on the starter but wont pick up. another day you go to it and it starts instantly on the button. when it is idling sometimes it just cuts out and then wont restart. Welcome jkkl, Check the earth on the battery, earth on frame of the bike and the plus and minus on the starter its-self. Stood for a long time so the starter might just need a bit of freeing up, or the brushes inside the starter might be stuck or coroded up. The idle issue--- you might just need to turn up the idle a bit, screw on the carb turn it slowely while watching the revs. What revs does it idle at now? EDIT: you have edited your post so I will do the same! Spraying with wd40 will help but you might need to actually take the earth wires off and give them a good cleaning. You could also just have a lazy starter not turning the engine fast enough for it to pick up. Do you have any clutch slip or drag putting extra pressure on the spining of the engine? Turn off the lights and things to give it a better chance. Link to comment Share on other sites More sharing options...
jkkl Posted February 4, 2010 Author Share Posted February 4, 2010 Welcome jkkl, Check the earth on the battery, earth on frame of the bike and the plus and minus on the starter its-self. Stood for a long time so the starter might just need a bit of freeing up, or the brushes inside the starter might be stuck or coroded up. The idle issue--- you might just need to turn up the idle a bit, screw on the carb turn it slowely while watching the revs. What revs does it idle at now? EDIT: you have edited your post so I will do the same! Spraying with wd40 will help but you might need to actually take the earth wires off and give them a good cleaning. You could also just have a lazy starter not turning the engine fast enough for it to pick up. Do you have any clutch slip or drag putting extra pressure on the spining of the engine? Turn off the lights and things to give it a better chance. many thanks i have checked the earth on the battery and will check the rest. i have have just been working on and it bumped again instantly but did not go on the starter until hot. if left for more than 10 mins it has to be bumped again. the starter doesnt always seem that lively and varies.is it possible the starter is pulling to much current and hinders starting.i have put a new clutch in as it was dragging and thought it might cure it. Link to comment Share on other sites More sharing options...
2 Wheels Posted February 4, 2010 Share Posted February 4, 2010 many thanks i have checked the earth on the battery and will check the rest. i have have just been working on and it bumped again instantly but did not go on the starter until hot. if left for more than 10 mins it has to be bumped again. the starter doesnt always seem that lively and varies.is it possible the starter is pulling to much current and hinders starting.i have put a new clutch in as it was dragging and thought it might cure it. So the clutch is not dragging now?? So the starter starts the bike when it is warmed up, i think the starter needs to be freed-up a bit. It isnt turning the engine fast enough when the bike is cold for it to fire up, try drowning the starter in wd40 getting inside it as much as possible. It could aslo be that the bike was left staning for so long that the engine it-self is all a bit tight, try going for a good spin to free everything up. This might take the pressure off the starter when it is trying to turn the engine, something is making it to hard for the starter to freely turn the engine. All this failing you could take the starter off and make sure it is clean and all bits are moveing freely as they should be. Link to comment Share on other sites More sharing options...
Moderator Airhead Posted February 4, 2010 Moderator Share Posted February 4, 2010 sounds like possible fuel starvation to me, what kind of fuel tap is it, a standard gravity tap or a vacuum operated tap. If its a vacuum tap you need to set it to 'PRI' for a while when you have had the carb in bits. What is the fuel flow to the carb like?, pull off the pipe and run some through to check for a good flow, again use 'PRI' if it is a vac tap Are you using the choke when its cold? ...Paul Link to comment Share on other sites More sharing options...
jkkl Posted February 5, 2010 Author Share Posted February 5, 2010 sounds like possible fuel starvation to me, what kind of fuel tap is it, a standard gravity tap or a vacuum operated tap. If its a vacuum tap you need to set it to 'PRI' for a while when you have had the carb in bits. What is the fuel flow to the carb like?, pull off the pipe and run some through to check for a good flow, again use 'PRI' if it is a vac tap Are you using the choke when its cold? ...Paul Hi its a gravity petrol tap and the flow is good. I have thought about fuel starvation but the carb is spotless inside and supply from the tank is good. I do use the choke from cold and have even tried a squirt of easy start in the air intake when not running to no avail. I have just tried starting it today it started reluctantly on the button but did so i let it warm up for 5 minutes it ran sweetly on tickover then suddenly cut out. I unscrewed the plug cap and held the lead about 5mm from the plug. Pressing the starter i got a weak erratic spark sometimes not at all, when it appeared stronger it tried to fire. I have tried 2 new plugs and changed the plug lead still no change. Last night i took it out for 30mins and it was fine. Link to comment Share on other sites More sharing options...
kishan Posted February 5, 2010 Share Posted February 5, 2010 sounds like the starter is worn out mate and needs changing Link to comment Share on other sites More sharing options...
2 Wheels Posted February 5, 2010 Share Posted February 5, 2010 Hi its a gravity petrol tap and the flow is good. I have thought about fuel starvation but the carb is spotless inside and supply from the tank is good. I do use the choke from cold and have even tried a squirt of easy start in the air intake when not running to no avail. I have just tried starting it today it started reluctantly on the button but did so i let it warm up for 5 minutes it ran sweetly on tickover then suddenly cut out. I unscrewed the plug cap and held the lead about 5mm from the plug. Pressing the starter i got a weak erratic spark sometimes not at all, when it appeared stronger it tried to fire. I have tried 2 new plugs and changed the plug lead still no change. Last night i took it out for 30mins and it was fine. You took it out for 30mins and it was fine but yet when you done the spark test it was week and often none. This is contradictory. You have 3 issues. The starter. The spark. The idleing 1st The spark: Right gap in plug. Plug out and into HT lead, earthen on the engine should have fat blue spark. If not start at HT lead and work all the way back to the coil. No broken wires or anything suspecious, no dampness in the leads or wires. There are tests on the coil but i dont know how to do them! If you have good blue spark then thats rulled out. 2nd The Idleing: How long are you leaving the choke on for. Should only need it for 1min or 2min max then off. Should be idleing arround 1500 to 2000max. Have you got the right fuel/air mixture going on. Is your piolet jet blocked, is there water in the float bowl. is the float level correct. 3rd The Starter: Take it off and clean it, check to make sure it workes proper. I think if you get using the bike a bit more and frequent that it Might just come back to its-self !!! Link to comment Share on other sites More sharing options...
Moderator Airhead Posted February 5, 2010 Moderator Share Posted February 5, 2010 A bit lost now, you seem to have covered most of the bases, Starts fine when hot, but cuts out for an unknown reason That might be either fuel (stood for 6 years...hope you did a good job of cleaning the carb) or losing spark (sometimes pulse coils will open circuit as the temperature rises, should not make for difficult starting when cold) or a remote chance that you havent set the valve clearance correct so losing compression when hot. ( again should not make for difficult starting when cold unless its way out) Link to comment Share on other sites More sharing options...
Moderator Cynic Posted February 6, 2010 Moderator Share Posted February 6, 2010 I'm a bit late to the party here but this is sounding electrical at me. You have tried a new plug CAP i take it. See what the resistance values are for the ig coil. And the cap (cap's typically 4K)You don't need a manual if you havent got one but check the value of the primary and secondary coil resistances, then get it hot and see what it is. You sould expect to see a slight drop if its warm. But any major changes get another. Link to comment Share on other sites More sharing options...
jkkl Posted February 7, 2010 Author Share Posted February 7, 2010 Anymore ideas anyone? Link to comment Share on other sites More sharing options...
2 Wheels Posted February 7, 2010 Share Posted February 7, 2010 Anymore ideas anyone? How did your tests go? Do you have a Fat Blue spark when the plug is out of the head, in the HT lead and earthed on the engine??????? If not, start doing Cynic's tests! Link to comment Share on other sites More sharing options...
Moderator Airhead Posted February 7, 2010 Moderator Share Posted February 7, 2010 Anymore ideas anyone? When it is hot and cuts out, check for spark immediately, if no spark then maybe you need a new pulser coil as these are sometimes known to open circuit when hot. Then let it cool down and if the spark returns it is more confimation of this. Link to comment Share on other sites More sharing options...
jkkl Posted February 7, 2010 Author Share Posted February 7, 2010 How did your tests go? Do you have a Fat Blue spark when the plug is out of the head, in the HT lead and earthed on the engine??????? If not, start doing Cynic's tests! Hi Everyone. My local yam dealer is supplying me Monday morning with some figures so i can check the coil and stator plate readings,so at the moment progress has ground to a halt. We did start it this morning it started easily on the button ran for about 5 minutes perfectly and suddenly just cut out. It wouldnt restart at all. We went back to it about 20 mins later it started easily but within a minute ran really rough misfirng, and only running on mid range revs and so we put it back in the garage fed up. I feel it might be a ignition coil breaking down any opinions welcome. Link to comment Share on other sites More sharing options...
2 Wheels Posted February 7, 2010 Share Posted February 7, 2010 Hi Everyone. My local yam dealer is supplying me Monday morning with some figures so i can check the coil and stator plate readings,so at the moment progress has ground to a halt. We did start it this morning it started easily on the button ran for about 5 minutes perfectly and suddenly just cut out. It wouldnt restart at all. We went back to it about 20 mins later it started easily but within a minute ran really rough misfirng, and only running on mid range revs and so we put it back in the garage fed up. I feel it might be a ignition coil breaking down any opinions welcome. Did you give the back tyre a good several hard kicks before slaming the garage door behind you I think this is an electrical prob, and unfortunatly I am not the best in this department but im sure the lads will help you out. Your carb and other things talked about seem to be performing as they should which leaves only electrical, Good Luck mate, ( Patients is a virtue ) Link to comment Share on other sites More sharing options...
jkkl Posted April 23, 2010 Author Share Posted April 23, 2010 Turns out the problem was the CDI unit. Link to comment Share on other sites More sharing options...
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