Post to end my fueling woes forever - vids + pics

[joriff]

28/01/09 -


This will be my thread to end all my other complaints and rants about my bike.

I'd like to sort this fueling thing out now. I have 2 days off and a handycam to record my progress. This is what the plugs look like after 100 miles, it might be a big file;

www.heritagelighting.co.uk/bike/plugs.jpg

And heres the video of it starting in the morning (today) with no choke on.

uk.youtube.com/watch?v=clY05C2ztU4

I'm stripping the carbs down today to look at jets, air filter and choke plungers.


So far i've had my carbs sonic cleaned, balanced, sync'd and a full service done on the bike. It fires on only 2 or 3 cylinders on start up usually, (not today for once!) cokes up plugs after 100 miles. Emulsion tubes look fine, new filters installed for fuel no crap in any of the breather tubes, removed and blocked off tube from cam cover to airbox as advised.

The one big suspect so far from CD is the choke plungers. I'll bust out the camera and get some shots!

[joriff]

Taken off the airbox and there was oil residue on the venturi? or at least the air inlet. where the airbox sits. No oil in the airbox though that i could see. No kinks in the main breather hose or white gunk. Hummmm..... ideas?

[darren]

if thats what its like from cold starting without the choke which will overfuel anyway, whats it like with the choke then knocking the choke of when warm,mine wont even start up without choke, but if it did it would probably be rough till warmed up, its hard to say what the smoke is without smelling it and been next to it, that could be just the cold, but if it has a distinct strong smell then overfueling could be a problem, if all airways are clear and there is no air sucking in anywhere, you could spray cold start or wd40 around areas like the head gasket,carb rubbers etc, if its sucking air the revs will rise with the wd been sucked in or its worn jets and needles possibly ,but still possibly choke

[CD]

My bet is still on the chokes

But if they seem ok and if the engine is OK when warm, but struggles to start from cold this might be an idea....

There might be a flat spot just above tickover. Probably not a problem in normal use as the engine will be running weak spot. But for starting the flat spot will be right where you need fuel to get the engine going above tickover. In that case the choke will be either too much or too little and inevitably you end up flooding the engine.

If this idea is right, the air screws on the dodgy carbs will need to be richened. Try one whole turn (360degs) write it down and see if its better or worse. Then adjust up or down each time writing down what you did. Make subsequent adjustments in smaller steps until its behaving right. If necessary you can go back to the original screw setting.

The snag is that a cold engine will flood and a warm engine won't easily show the symptoms so it will have to be trial and error. Hence the copious notes.

[darren]

Jan 28, 2009 14:07:38 GMT CD said:

My bet is still on the chokes

But if they seem ok and if the engine is OK when warm, but struggles to start from cold this might be an idea....

There might be a flat spot just above tickover. Probably not a problem in normal use as the engine will be running weak spot. But for starting the flat spot will be right where you need fuel to get the engine going above tickover. In that case the choke will be either too much or too little and inevitably you end up flooding the engine.

If this idea is right, the air screws on the dodgy carbs will need to be richened. Try one whole turn (360degs) write it down and see if its better or worse. Then adjust up or down each time writing down what you did. Make subsequent adjustments in smaller steps until its behaving right. If necessary you can go back to the original screw setting.

The snag is that a cold engine will flood and a warm engine won't easily show the symptoms so it will have to be trial and error. Hence the copious notes.

the choke was my original thought also, due to the fact mine wont even start at all until about five or six attemps, but soon as I put throttle on it will die, so starting without choke gives an indication of choke or air getting in somewhere

[joriff]

Thanks for the input guys, really apreciate it. I've taken the plungers out and they looked in good condition. I cleaned them all up just incase dirt was in the seal and put them back. Used armorall rubber conditioner on the seals.

I also checked the mechanism was sealing them all shut properly and it looked like it was. I changed the idle screws to 2 turns as per the haynes book and removed the air filter. Once i got it started (about 6 attempts with choke) it was just as smoky if not more, the spark plugs were wet too. It could be that i used too much choke to get her started and it was just that the fuel hadn't got through yet.

Like you say though, it is cold out and i need to take it on a long run to see if i've done anything.


Could the float heights be causing a problem? they are all the same, 13mm from the base of the carb housing to the top of one of the round floaty things.

[joriff]

Float heights were actually 10-11mm, re-adjusted and am rebuilding... gets tiresome taking apart then putting back together!

[darren]

do you also have a good strong spark?

[joriff]

To be honest darren i've not even given it a single thought! I have new plugs in there but have to continually clean them. I will check tommorow in the morning after i take it for a long run!

[CD]

Bad luck those chokes have no right to be clean.

Have the carbs ever been taken off the bike? Could there be an air leak into the manifolds between engine and carbs? While the tank is off it might be worth a look. It becomes an even longer job (with no certainty of success), but who knows what bodging has gone on before.

[darren]

if you want to check for air sucking in, do as said above and spray cold start or wd40 around the carb rubbers and head gasket area, do the head gasket area when its still a bit cold, or it will just evaporate, the revs will rise as cold start is more combustable than petrol, as it will be sucked into the chamber and burnt, you will also notice black smoke from the exhaust as it burns