Will not start unless i cover the carb with my hand.

[mark_mc]

Hi, and thanks for looking, hopefully someone may be able to help.

My problem is: I just can't get my bike to start unless i put my hand over the carb as i kick start the bugger.

The engine is a LI150 with a 175 kit on it JL pipe and a 30mm Dellorto, i usually run it with a MB remote filter but i have removed the filter due to my problem with starting.

The Scooter is also fitted with electronic ignition AC and has a nice spark.

When i check the plug the signs are it's possibly running a wee bit rich, but i would rather have it that way.

The strange thing is, my mate has the same problem, his is just about the same, 30 delay on a stage 4 200 and a MB Devtour exhaust. and it just will not start unless he puts his hand over the carb when starting.

Apologies in advance if this subject has been thrashed to death in the past, i have had a quick search to see if there are any similar threads.

Any help or advice with this will be most gratefully received

Thanks Mark.

[Toddy]

Just a simple question first is your Choke Mechanism working ?

[MickYork]

As above.

What size are your jets ? you may need a larger choke jet ?

[coaster]

The cold weather will be having an effect too and causing the mixture to be a bit lean. As already said though, check that your choke is actually working, I had similar problems a year or so back and after breaking the kickstart from kicking it so much I found the nipple had come off the end of the choke cable

Good technique helps too, you should always hold the throttle closed when starting, don't be wringing the throttle.

[mark_mc]

Thanks very much for the replies.

I will play about with the scooter tomorrow, firstly i will check the choke plunger is opening and closing properly, then i will try to start the scooter with just the choke and no throttle to see how i get on.

Then no matter how i get on i will remove the carb, (even if its just to give it a good clean out)

I will check all the jets, needle, float valve and make sure the rubber mount is in good condition. Take a note of all jet sizes needle size so as i can at least quote the contents and take to from there

Thanks again for the replies and i now have something to work on tomorrow

Cheers Mark

[johnnyXS]

I would say that a 30mm venturi is way large for a 175 engine .
The problem with large venturi is that there is a huge drop in pressure when the throttle is opened which cannot draw enough fuel especially when the engine is cold.

If your pilot jet is the correct size and the air or fuel mix screw is set correctly the scoot should cold start on zero throttle with full choke. However that said, in cold weather the fuel is going to form droplets on the wall of the manifold giving a lean mixture in the cylinder until the engine warms up and the fuel atomizes properly.

If it doesn't start in a couple of kicks there is a natural tenancy to open up the throttle which will defeat the cold start mechanism and probably flood the cylinder and spark plug .

If I were using a scoot with no air filter in the winter I would buy a can of EasyStart and give a squirt of that into the carb before starting