I have to pedal my HT build for 1-2 mins before the motor kicks in! He

[jamesloper]

Alright here's what happened: Went outside, cold day in Michigan. I flipped the choke all the way up and poked the primer about 5 times. I released the clutch and pedaled. Pop! Got some immediate lurches. But they didn't last and I pedaled for about 2 more mins until finally I decided it wasn't going to work and so I flipped the choke all the way down and it immediately started working.

By the way, I never really have gotten the bike to work with the choke in the top position. I think it starves the engine of fuel/air too much.

 

[motorpsycho]

the reason that it immediately started after flipping the choke down is because when you were trying to start it with the choke in the up position, it loaded the cylinder with fuel.
with the choke in the up position, it does not starve the engine of fue/air...it makes it so the engine does not take it too much air.
more gas/ less air makes for easier starting. when you flip the choke down, you are "adding" more air to make it run right.

you will have to play with the choke and it's settings to get the hang of it.
i mean seriously, i flip my choke up, push the primer 4-5 times, coast down my driveway, pop the clutch and the motor starts. before it does, i reach down and flip the choke all the way down and work the throttle.
it's just that easy...and i NEVER have to use the choke if the air temp is about 60 degrees.

 

[Sgt. Howard]

it is also possible that my choke won't fully close off the throat of the carb- quality control on these things is no better than it ought to be- motorpsycho's regimen might be just the ticket, play with it until you find out what works. In fact, once you get a pop, turn the handle either half-way or all the way down and see if that doesn't settle the issue.
the Old Sgt.

 

[motorpsycho]

it is also possible that my choke won't fully close off the throat of the carb- quality control on these things is no better than it ought to be- motorpsycho's regimen might be just the ticket, play with it until you find out what works. In fact, once you get a pop, turn the handle either half-way or all the way down and see if that doesn't settle the issue.
the Old Sgt.

well, if you take off the air filter and close the choke, you will be able to see the choke plate. you will be able to see if it is fully covering the carb throat when you have the choke closed (lever in the up position).
the choke plate has a hole in the center to allow a precise amount of air through, so even when the choke is fully closed, you are still not blocking off all of the air. by closing the choke you are reducing the amount of air, but increasing the speed of the air that is being sucked into the carb. the hole in the carb plate creates a venturi effect. the smaller the hole, the faster air will move when it's sucked into the carb.(a venturi looks like an hour glass)
think of it the same as when you have a garden hose with no sprayer on the end of it., the water just kind of lazily flows out of the end, as soon as you put your thumb over the end of the hose, you have reduced the flow, but increased the pressure or speed, which makes the water spray out of the hose.
it's the same thing when you close the choke. the choke plate is acting as your thumb over the end of a garden hose.

 

[Skyliner70cc]

A lot of the HT carbs chokes are flimsy and will not work, e.g. actually more the flat slide that covers the intake to perform the choke function.

 

[jamesloper]

Well I filled up my tank, gapped my sparkplug to .026 mm (it's mm right?), had the choke all the way down, and ***on the first cycle*** the engine kicked in full blast. Crazzyyyy!! I think it's because the tank was fuller and hence wanted to push more gas into the carb. Anyway, my bike now starts up immediately! Thanks for all the help

 

[Skyliner70cc]

Glad to see you got it figured out. None of my engines start at full choke. Its always 1/2 to 3/4 chocke. What I do now is drill the hole out slightly larger on the choke valve so full choke allows engine to start. Otherwise I would fiddle with choke as I pedaled.

New engines are sometimes harder to start and a little bit of breaking helps rings seal a little better.