Hi I have a 1959 C15s scrambler. It was a box of bits that over the last year i 've been putting back together. Finally it came round to trying to start it and despite the awkward J shaped kickstart it eventually was coaxed into life and I let it tick over for about a minute. After that nothing, it barely tried to fire. Next day similar with a brief try then nothing. Next day got it going, ticked over a while then wouldn't start after that. The plug is pretty dry. i took the carb off and tried a bigger pilot jet (30) still nothing. Air screw tried in and out. Plenty of fuel in the bowl and it comes out when the tickler pressed. Spark fine from electrex ignition. it just doen't seem to be taking fuel in, all the carb holes look perfectly clean.
the carb is a monobloc 376/20 which is 1" bore rather than the 376/222 15/16 which should be on the bike. I can't see that would make that much difference just on starting but please correct me if I'm wrong.
Its fresh fuel as well.
Any ideas please, I'm meant to be doing the beamish run in September on the bike, time is running out!
When the bike conks out, have you checked to see if there is any fuel in the carb?
Switch off the petrol tap and undo the bottom nut to see if any fuel drains out and how much. That will eliminate the needle valve from sticking. If the carb is full of fuel when it conks out, either there must be a blockage ( probably in the idle circuit ) or it is not fuel starvation causing the bike to die.
Thanks for the reply, the bike didn't die I stopped it. It just won't go again, plenty of fuel in the bowl as the tickler flooded straight away. I've even taken the foot pegs off to get a better swing on the silly j shaped kickstart. When I took the pilot jet cover off with the carb in situ the fuel drained out through the pilot jet and there was plenty came out so I think the bowl was full. All a bit strange, I'm hoping to have another play this weekend but at moment run out of ideas, maybe it's time to try bump start.
Have you checked the obvious?
Have you got a spark at the plug? Have the points slipped or closed?
Is the plug wet after you have kicked it over a few times?
Half open the throttle when trying to start - some engines ( mine included) wont start unless the throttle is at half open!
If you have got fuel and a spark, something will happen!
Thanks for the reply Adrian. Its a great spark as I'm on Electrex ignition. Its got to be the carb, I put some wire through the pilot hole which was clear and as I said tried another pilot jet. I'm contemplating buying a new carb but it seems a bit extreme as the old one looks to be ok but it would give me the correct bore. Also had a clutch slip problem which wasn't helping after I put probably the wrong oil in so I've just put some new plates in and ordered the correct JASO MA spec oil. When I tried it yesterday it was trying to go but then stopped trying even though there was plenty of fuel in the bowl. The plug isn't as wet as I would expect. I will try again tonight but am starting to get a sore knee!
Where abouts are you? I'm sure someone could lend you a carb to try. I'm between Ashby and Lichfield and have a spare carb to try if you were local!
Thanks Adrian, I bit the bullet and bought a new one. Hopefully will have it today or tomorrow, will post the result when I know.
New carb put on, tried it without choke slide and no success, put the the choke slide in and still nothing but a very wet plug. Left it a day put a new iridium plug in and at the same time stuck the new registration number on that had just arrived. Couple of kicks and then it started with a handful of throttle. I left it running a good five minutes or so to get things nice and hot then stopped it.
So was it the new plug that helped or a bike with an identity crisis from not having a number plate?
Hopefully tonight we might venture out of the garage.
Always worth checking the easy things ( and cheap things ) first!
Unless there is a blockage the carbs are very reliable. Hopefully you have sorted the problem out!
The carb on it was the wrong size so quite happy to get the new one. I'd tried 3 plugs on it as well so guess its more the carb that sorted it than the plug, maybe a combination of both.