mickb Posted July 21, 2011 Posted July 21, 2011 Hi All, I have a 250LC 1980, I am having running problems when on the road at around 5,000 rpm it will run fine, if i open it up through the gears for aaround 30 seconds, it just cuts out, just like when you go from fuel on to reserve. I then pull over and the bike kickes over after about 30 seconds. the bike is all standard with the right size jets etc, I have removed the tank and cleaned, I have cleaned and checked the fuel tap as well. I have run out of ideas now, has anyone had come across this before? Is there anything else I need to check, is driving me mad as the bike goes very well if you dont open it up!! Any suggestions welcome. Thanks, Mick.
up.yours Posted July 21, 2011 Posted July 21, 2011 try removing the carbs and giving them a thurough going over , that cured my probs. i had same symptoms as you described on my 350.
mickb Posted July 22, 2011 Author Posted July 22, 2011 Hi, have already removed carbs and totally stripped with no difference. Thanks, Mick.
Moderator Airhead Posted July 22, 2011 Moderator Posted July 22, 2011 Slow fuel supply through your tap...blocked screen either in the tap bowl or within the tank?
mickb Posted July 22, 2011 Author Posted July 22, 2011 Float levels are ok, have adjusted both ways as well to see if any different with no change. I think the blocked screen is a good call, I will have a go at that and post back, bear with me for a week as going away in the morning, will report back on my return. Thanks, Mick.
mickb Posted August 4, 2011 Author Posted August 4, 2011 Hi all, New fuel tap fitted, still no different, the only thing untouched is the reed valves. This is seriously driving me mad now. Mick.
Moderator Cynic Posted August 4, 2011 Moderator Posted August 4, 2011 some yams have a little screen filter in the carb fuel inlet. Second, sometimes rubber can flake inside the fuel pipe and act like non return valves restricting flow Are the float chamber vents clear One last one for you, bit naughty but has worked for me in the past. Give the float heights a tweak, not much just enough to lift the level in the carb by maybe 1mm and see what happens. If it works your floats are losing boyancy.
Moderator Airhead Posted August 4, 2011 Moderator Posted August 4, 2011 Hi all, New fuel tap fitted, still no different, the only thing untouched is the reed valves. This is seriously driving me mad now. Mick. is the fault still the same as you reported? Have you got a strong fuel flow now with your 'new' tap ? some yams have a little screen filter in the carb fuel inlet. Second, sometimes rubber can flake inside the fuel pipe and act like non return valves restricting flow Are the float chamber vents clear One last one for you, bit naughty but has worked for me in the past. Give the float heights a tweak, not much just enough to lift the level in the carb by maybe 1mm and see what happens. If it works your floats are losing boyancy. yeah check these points too, also I once found chips of rust in a carb, situated between the fuel inlet spigot and the float valve seat, had to remove the valve seat and blow it out.
mickb Posted August 4, 2011 Author Posted August 4, 2011 Thanks for the feedback. The fault is still the same as before and the flow rate looks the same with the new tap, I have already made adjustments to the float levels with no change, there are new fuel lines fitted. I have also borrowed a set of carbs from a mate and fitted them with exactly the same problem. Thanks, Mick.
Moderator Airhead Posted August 4, 2011 Moderator Posted August 4, 2011 Thanks for the feedback. The fault is still the same as before and the flow rate looks the same with the new tap, I have already made adjustments to the float levels with no change, there are new fuel lines fitted. I have also borrowed a set of carbs from a mate and fitted them with exactly the same problem. Thanks, Mick. we have been suspecting a fuelling issue as this is most likely, not as likely now though as you have addressed this? how about an electrical fault, is it out of action for long enough to check for a spark at that time?
Moderator Cynic Posted August 4, 2011 Moderator Posted August 4, 2011 Right then baring a blocked tank vent, were done with the fuel system then. Swapping in a set of good carbs has put paid to that tac. Lets talk ignition, plugs changed i'm guessing. Have you checked for a spark when she's cut out? Your mate wouldn't have an ig coil handy too by any chance.
mickb Posted August 4, 2011 Author Posted August 4, 2011 Yep new plugs as well, I was wondering electrical after that lot. I dont think down long enought to check for a spark, as soon as I come to a rolling stop she kicks over. I will make some enquiries on another coil for a trial. Thanks, Mick.
mickb Posted August 8, 2011 Author Posted August 8, 2011 Hi All, spare coil fitted, running a bit better, can go up through the gears, still a bit flat up there but will clear if you give a hand full, not shutting down as before. There is now a missfire on tickover as well to add to the fun of things! Mick.
mickb Posted August 9, 2011 Author Posted August 9, 2011 Hi Also just thought, what about ignition timing?
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