So my bike has been rebuilt and normally is an easy starter. Haven't started for a few weeks and now it starts within first few kicks but won't stay running. Runs great for 3 to 4 seconds then coughs and dies, sometimes u can see a small flame out of the carb as it coughs and dies. If I keep kicking it runs longer as bike warms up and is eventually fine. Seems like I have to "over tickle" the carb to keep it running. Until it warms completely it seems like the bike misses every once in a while. I'm thinking fuel starvation but at bowl or needle float? Not sure. Thanks for the help

email (option): Jeff@infinitymedspa.com

Well just start by taking the float bowl off for a clean and remove and blow out the main and needle jets. If you've never done this before? Just ask and we will talk you through it. Ron

email (option): ronpier@talk21.com

Don't know if you saw the Forum picture of a rider with spurs on his boots...try giving it a little clip with both heels.

Alternatively, a light thrashing with some sort of makeshift riding crop might encourage it. A length of whippy willow does the trick for me.

Swearing loudly really works, but on a still day can carry somewhat.

email (option): sacombsashtrees@hotmail.com

If it is 'spitting back' in the carb as soon as you start to open the throttle the mixture is weak...and it does sound like that...

Clean out the carb as mentioned by Ron and check the mounting flange of the carb to ensure it is flat, also check the gaskets are good....Ian

email (option): ian@wright52.plus.com

I think Basil F used a silver birch sapling
You could try similar.....

These type 276 carbs are notorious for either constant flooding or not letting fuel in.
If it was all working before the layup/overhaul/etc. and you have not done anything to the carb.
Then it almost always comes down to the float and valve rod assembly and dirt or white corrosion caused by fuel causing things to stick.

Take float off (leave carb connected to head), dismantle and clean.
Before you refit to carb body give it a shake to see if it rattles - it should, otherwise you have trapped something.

My newly purchased 3HW did exactly same as yours - no fuel getting to the engine.
The float was no longer clipped to the float rod (the clip had broken)and the rod was sticking in the Mazak float-camber top.
I had a an older brass float camber top which nicely stops the sticking problem (look out for them @ auto-jumbles)and new float + clip solved all the problems - actually ticks over now!?

email (option): GINANTONIK@TISCALI.CO.UK

Thanks guys for all the help. Sounds like we are on the same page I'll check the float this weekend. Ps tried th swearing thing and just like my wife it didn't work at all. :)

Hi,

Is the problem also occuring when you have opened the trottle 1/3?
Perhaps the the very small hole inside the carberatur brass block is blocked, this regulates the idling. (because of oxcidation by the "new" petrol.
I had the same problem with my WD/CO last year

Just a thought.

Cheers,

Leon

Hi,

I had a problem that I also solved like you, Leon,
But in my case, the bike would not start without pressing the tickler
Even when it was hot, and I could feel some loss of "pulling".

After cleaning the brass idle passage, it started without any issues
And usually with no deed of the tickler even after standing for a week,
And there was an improvement in handling.
I think I could use the entire 13HP !

Noam.

email (option): noam10@gmail.com

Hi,

Is the problem also occuring when you have opened the trottle 1/3?
Perhaps the the very small hole inside the carberatur brass block is blocked, this regulates the idling. (because of oxcidation by the "new" petrol.
I had the same problem with my WD/CO last year

Just a thought.

Cheers,

Leon [/quote]

Hi Leon
I'm doing the carb cleaning this weekend my kids have kept me busy until recently... I've taken the carb off many times, but I don't remember seeing the hole in the brass block that you are talking about. Can you please explain? Thank you

Jeff if you look down the carb throat from the flange end with a torch, you will see a tiny pin hole at the bottom towards the slide. There is a corresponding drilling in the brass jet block. You need to remove the jet block to poke the holes out with a thin piece of wire. Clean out all the drillings/jets with petrol/thinners and blow everything through with an air line whilst it's apart. check that the float needle is seating properly by, turn the float bowl upside down and try blowing through the petrol pipe banjo. Turn it up the right way to see it's free. Ron

email (option): ronpier@talk21.com

The jet block can be a tight fit in the carb body and application of excessive force when attempting to remove it can easily damage it beyond use...

I use a piece of wood that fits snuggly into the top of the carb body and has a flat end that sits on the top face of the jet block...It is also long enough to protrude a couple of inches when fitted in place....

Heat the carb body/jet block in some boiling water then drop in the piece of wood and a few moderate blows with a mallet will get the jet block moving...

Alternatively knock the top end of the wood onto a hard surface...

The lower end of the jet block is the part that is usually a tight fit in the body.

Once it has moved the first 3/4" or so the remainder will come out easily...

If necessary lightly emery the bottom part of the inside of the carb body and the lower section of the jet block to remove any burrs/corrosion before refitting....That is what generally causes the tightness....Ian

email (option): ian@wright52.plus.com

Remove the idle screw.

I use a syring with some small diameter plastic tube attached, fill syring with petrol or similar, try and get the plastic tube sealing over the small hole on carb floor mentioned by Ron, and give it a squirt - you should get petrol/etc back into the idle screw hole.

I tend to use a synthetic bristle from a brush or something, rather than a fine wire, which could i suppose damage the airway.

The problem is a form of corrosion, there must be a some solvent that will dissolve the (white) corrosion without destroying the MAZAC casting.
I have heard of boiling in vinegar (acetic acid) to clean out MK1 Concentrics.

Ive turned to using electric garden tools rather than petro ones as i'm fed up trying to get the b****ds started again every spring - i've managed to tear ligaments getting a scarifier going!

Or just put some fresh fuel in it.

Richard

sadly it never seems as easy at that, its a well documented problem and if you run any of the Concentric mk1 Amal carbs - ITS A MAJOR PROBLEM!!!!

Top tip - rejet a two stroke Concentric to 4 stroke spec - at least then you can remove the pilot jet to help clean things out.

I tend to run the ES2 on the petrol/oil (32:1) left over from my MX/Enduro'ing - on the basis;

1/ it needs using, and i'm yorkshire.
2/ prevent corrosion in the fuel tank (?)
3/ there's sod all lubrication to the valve gear on this bike.

As a side-bar - i don't seem to have any fuzzing up problems, maybe thats the solution ?

I had a similar problem and solved it by fitting a float level indicator. If the level is right, it starts second kick. If the level is not right, I don't even try to start it.

I can't take credit for this as I saw it somewhere, possibly on this forum.

To make the elbow, partially drill the pieces in a lathe, then braze, then finish drilling by hand. The back nut is required to keep the nozzle pointing up and the assembly is sealed with loctite.

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email (option): pvlietstra@gmail.com