PaulD13 Posted April 21, 2021 Share Posted April 21, 2021 Hi guys new to the forum with a very stubborn YR5. I've totally rebuilt the motor after buying the bike as a non runner. Rebore pistons crank all the ignition and charging system a new Motobatt battery plus the carbs ultrasonic cleaned and checked. The problem is when I go out for a run the bike starts and ticks over fine but two miles of so into the run the bike either packs in altogether or drops onto one cylinder first and then stops and won't restart. Checking straight away the bike has a good spark on both sides and the plugs are wet but won't start? I push the bike home and it still won't start but if I leave it overnight it starts and runs perfect until I go for a run and the whole saga starts again. Oh plus even running with the filler cap removed makes no difference. Any suggestions welcome before I give it a Viking funeral 1 Link to comment Share on other sites More sharing options...
Moderator Snakebite68 Posted April 21, 2021 Moderator Share Posted April 21, 2021 My first thought would be heat ceasing... Does it actually turn over? If not, check to see whether it starts as soon as it has gone cold (rather than overnight). Link to comment Share on other sites More sharing options...
PaulD13 Posted April 21, 2021 Author Share Posted April 21, 2021 4 hours ago, Snakebite68 said: My first thought would be heat ceasing... Does it actually turn over? If not, check to see whether it starts as soon as it has gone cold (rather than overnight). Not seized as I can kick it over easily but it refuses to start. The carbs are mikuni vm28sc with the floats separate from the float valve plate thing. Do I measure the height from the plate as I can't see any other way of doing it? Link to comment Share on other sites More sharing options...
Moderator Snakebite68 Posted April 21, 2021 Moderator Share Posted April 21, 2021 Carbs are magic items beyond the ken of myself... But I'm sure there's plenty of others in here that know about them lol Link to comment Share on other sites More sharing options...
blackhat250 Posted April 27, 2021 Share Posted April 27, 2021 Well " i think its a poor battery, hence starts when left, is it charging, ie 14.2 volts etc, [ running], it would do this run fine for few miles, then fizzle out, Link to comment Share on other sites More sharing options...
Moderator Snakebite68 Posted April 27, 2021 Moderator Share Posted April 27, 2021 3 hours ago, blackhat250 said: Well " i think its a poor battery, hence starts when left, is it charging, ie 14.2 volts etc, [ running], it would do this run fine for few miles, then fizzle out, Even if the battery died, wouldn't it continue to run on the alternator? Link to comment Share on other sites More sharing options...
blackhat250 Posted April 28, 2021 Share Posted April 28, 2021 No " not Rd"s there not magneto ignition, [ small Dt"s etc are ] they need good battery, or the Vape iggy system , this will run without , Link to comment Share on other sites More sharing options...
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