keychange Posted January 8, 2011 Report Share Posted January 8, 2011 I have had chronic tuning problems with my 247T and spent hours on forums and decades (it feels like pulling carbie on and off, changing jets, needles ..... I recently had to replace the woodruff key got it started but it was dying for no reason at low revs and then hard to start. So I decided to pull the carb off for a routine clean and while I was at it I lowered the needle just to see what affect it would have. To my delight the needle adjustment appeared to improve my top end performance - but the cleaned carbie did not fix the dying. The bike is going great - probably best I have ever had it but for example when riding down a cow track leading to a creek crossing it just died - as if no fuel ( I have had similar issues before but this feels different) - today it was idling happily while I closed a gate then died for no reason and it is then quite hard to restart (this does sound familiar) anyway I was thinking about what I should try next with the carbie - and I really have done everything - then it occurred to me that if my timing was just a smidge too advanced it could cause this couldn't it? I know from experience the 247 is a bugger to start when too advanced but this might be just a gnat's knacker out - any thoughts? Quote Link to comment Share on other sites More sharing options...
smelling123 Posted January 8, 2011 Report Share Posted January 8, 2011 Have you tried a new condensor mate? or is it electronic ignition? My Bultaco does exactly what you're saying - changed the condensor and all OK.. My dads Monty sheared the woodruff key - lap the rotor on the shaft with fine valve grinding paste, clean off then use a small amount of bearing fit on the taper (I know an engineer wouldn't like that!). Don't forget the old Spanish carbs wear like hell - could it be just worn out? Quote Link to comment Share on other sites More sharing options...
keychange Posted January 8, 2011 Author Report Share Posted January 8, 2011 Have you tried a new condensor mate? or is it electronic ignition? My Bultaco does exactly what you're saying - changed the condensor and all OK.. My dads Monty sheared the woodruff key - lap the rotor on the shaft with fine valve grinding paste, clean off then use a small amount of bearing fit on the taper (I know an engineer wouldn't like that!). Don't forget the old Spanish carbs wear like hell - could it be just worn out? Yes replaced condensor and every part in the Amal and even tried a Mikuni which didn't fix the issue at that time but I worked on other things such as stator wiring, plug gap, exhaust flange leak and these all improved but while the bike hasn't done the stall thing again until n ow I am guessing that in refitting the stator I might have just advanced it a little and my question is - could this be an explanation??? Quote Link to comment Share on other sites More sharing options...
keychange Posted January 9, 2011 Author Report Share Posted January 9, 2011 Happy to announce that it worked - just one degree retard and idle stall issue fixed. So I now have a Cota 247 that starts first kick, idles and has good power across the range. Just one little thing and this is something I've had for ages. Once the bike is fully warmed up the idle increases - I have done all of the checks etc. I get round this by setting the idle low and adjusting it up on the throttle until it is hot then back that off as required. What I notice is that there is probably 1/8th turn on the idle adjust screw between a good idle and a high idle ie: about 500 rpm increase (guessing) any ideas on this little conundrum ... Quote Link to comment Share on other sites More sharing options...
sdm Posted January 10, 2011 Report Share Posted January 10, 2011 Hard to know for sure but it could be your crankshaft seals are shot and leaking air. If the clutch side leaks then it will suck primary oil into the bottom and smoke quite a bit. If it is the mag side it will suck air giving you a lean condition. If you have been through the carb and all is sealed ok there then I would suspect the bottom seals. It should just sit there and idle when hot and not gain any rpm. Sam Quote Link to comment Share on other sites More sharing options...
keychange Posted January 10, 2011 Author Report Share Posted January 10, 2011 Hard to know for sure but it could be your crankshaft seals are shot and leaking air. If the clutch side leaks then it will suck primary oil into the bottom and smoke quite a bit. If it is the mag side it will suck air giving you a lean condition. If you have been through the carb and all is sealed ok there then I would suspect the bottom seals. It should just sit there and idle when hot and not gain any rpm. Sam Thanks Sam - no excess oil burn and mag side seal has been replaced. What do you mean by bottom seals? Quote Link to comment Share on other sites More sharing options...
sdm Posted January 12, 2011 Report Share Posted January 12, 2011 Thanks Sam - no excess oil burn and mag side seal has been replaced. What do you mean by bottom seals? Sorry ... I just meant the crankshaft seals and if you have replaced them then it must be ok. Sam Quote Link to comment Share on other sites More sharing options...
bpilgrim Posted January 15, 2011 Report Share Posted January 15, 2011 Have you tried a new condensor mate? or is it electronic ignition? My Bultaco does exactly what you're saying - changed the condensor and all OK.. My dads Monty sheared the woodruff key - lap the rotor on the shaft with fine valve grinding paste, clean off then use a small amount of bearing fit on the taper (I know an engineer wouldn't like that!). Don't forget the old Spanish carbs wear like hell - could it be just worn out? I put the ignition flywheel in the oven! After I first rebuilt the bike it sheared a key on the first start and I read it is a common failure. So I cleaned it up, new woodruff key, put it in the oven and used some loctite too! It hasn't sheared since! The difficult bit was lining up a 150degC flywheel with the key! Quote Link to comment Share on other sites More sharing options...
sdm Posted January 17, 2011 Report Share Posted January 17, 2011 Happy to announce that it worked - just one degree retard and idle stall issue fixed. So I now have a Cota 247 that starts first kick, idles and has good power across the range. Just one little thing and this is something I've had for ages. Once the bike is fully warmed up the idle increases - I have done all of the checks etc. I get round this by setting the idle low and adjusting it up on the throttle until it is hot then back that off as required. What I notice is that there is probably 1/8th turn on the idle adjust screw between a good idle and a high idle ie: about 500 rpm increase (guessing) any ideas on this little conundrum ... About the only other thing to check if you have eliminated all the possibilities of air leaks is you might want to go a bit larger on the pilot jet. Or It could be partially plugged or or it's circuit could be. When you say hard starting does it seem to load up or flood or does is seem to be needing more fuel? I always shut off my fuel tap when the bike is sitting or it will load the engine with raw fuel. Quote Link to comment Share on other sites More sharing options...
belldane Posted January 18, 2011 Report Share Posted January 18, 2011 About the only other thing to check if you have eliminated all the possibilities of air leaks is you might want to go a bit larger on the pilot jet. Or It could be partially plugged or or it's circuit could be. When you say hard starting does it seem to load up or flood or does is seem to be needing more fuel? I always shut off my fuel tap when the bike is sitting or it will load the engine with raw fuel. Quote Link to comment Share on other sites More sharing options...
belldane Posted January 18, 2011 Report Share Posted January 18, 2011 Hi Just sitting here thinking about that idle problem. If you turn the idle screw up so that it is idling higher then it should be, does the motor stall ? If it doesn't the problem could be that the slot on the slide where the idle needle goes into has worn and no matter what you do can't get it right. A bit of a turn to the right and the idle is high. A bit of a turn to the left and it stops and there is no adjustment in between. Just a thought but you seem to have covered all the other things that are causing you problems. See how you go Quote Link to comment Share on other sites More sharing options...
keychange Posted January 18, 2011 Author Report Share Posted January 18, 2011 Hi Just sitting here thinking about that idle problem. If you turn the idle screw up so that it is idling higher then it should be, does the motor stall ? If it doesn't the problem could be that the slot on the slide where the idle needle goes into has worn and no matter what you do can't get it right. A bit of a turn to the right and the idle is high. A bit of a turn to the left and it stops and there is no adjustment in between. Just a thought but you seem to have covered all the other things that are causing you problems. See how you go Idle adjustment at cold appears normal but when hot there is only a slight turn to increase a lot I'd say 1/8th turn when hot = 1/2 normal turn. But only on increase - lowering from normal idle the adjustment lowers as normal to an eventual stall - does that make sense. Maybe the slide is worn and leaks more as the body of the carbie heats up and expands Quote Link to comment Share on other sites More sharing options...
belldane Posted January 19, 2011 Report Share Posted January 19, 2011 What sort of carb is on the bike? No doubt the old tickle me until I drop fuel all over the engine covers sort. If it is that sort the carb could be worn out. The slide and the carb were made out of the same material and after much use they were stuffed. Do you have anyone in your area with a similar bike ? If you do and their bike is running properly swap carbs and see what happens. Whereabouts in Australia are you ? Quote Link to comment Share on other sites More sharing options...
keychange Posted January 19, 2011 Author Report Share Posted January 19, 2011 What sort of carb is on the bike? No doubt the old tickle me until I drop fuel all over the engine covers sort. If it is that sort the carb could be worn out. The slide and the carb were made out of the same material and after much use they were stuffed. Do you have anyone in your area with a similar bike ? If you do and their bike is running properly swap carbs and see what happens. Whereabouts in Australia are you ? yeah it's an Amal and I did borrow a Mikuni a while back but I was focused on a slightly different angle of the issue at the time and probably didn't give it a fair trial - maybe my mate Ross will lend it to me again when he reads this - I already owe him a stack of beers :beer: Quote Link to comment Share on other sites More sharing options...
belldane Posted January 19, 2011 Report Share Posted January 19, 2011 If you have a lot of time on your hands by all means try the Mikuni. I have a a couple of 247's with the same carb as yours and a 348 which I tried to fit a Mikuni to as it just was not running properly. In the end I just gave up, jetting just was not right, great down low or up the creek up high or vice a versa. In the up and ended buying a spare 348T for parts and swapped the carb over. Problem solved. It ran really well but had the original carb re-sleeved anyway by a bloke near Sydney and all my problems are over. I know the 348's have a different carb. Is there any one you know with a 247 with a carb the same as yours ? That would save you a lot of time and expense. One thing that does come to mind which I should have mentioned earlier is whether you have checked that bakelite spacer between the carb and the cylinder. If it has a slight crack it can cause all of the symptoms you are experiencing. I have a mate in England whom I met through this forum and he was having the same problems as you. I posted a spare spacer I had here and he as happy as Larry. Bike starts first or second kick all the time and no stalling any more. He did tell me that the only way he could get it to go when it stopped was to take the plug out and do the old a bit of petrol down the plughole routine. I reckon the problem is something really simple after all there is not much that can go wrong with those motors and you seem to have covered nearly everything. You can PM me if you like but I am off to Canberra in the morning and have no idea when I will get back. Manuel Quote Link to comment Share on other sites More sharing options...
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