ET4 - Starts at full throttle

[hazbaz]

Hello,

Been chasing some issues with the scoot today.

Have done some work (see below), and now the bike starts at FULL throttle! Throttle cable isn’t sticking. Throttle is closed at carb. Have made sure that the throttle body is properly seated in intake, so pretty sure there’s no air leaks. Idle screw is an issue, as I don’t understand how it works (what it does on the carb), and I’m sure it’s set wrong, but changing it doesn’t seem to effect the throttle. Could something be stuck open in the carb? What is the most likely source of this? TIA.


Drained all the E10 out of it, replaced fuel tap, line and vacuum hose with new. Filled with E5 premium. Should make it happier.

Removed carb, dismantled, checked it all over. Very clean, looks like it was serviced not long before I bought it. Put it back together and then back on scoot. Did a compression test beforehand, 230 PSI. Nice healthy engine.

Changed out fuel contaminated oil for new.

[scooterbooter]

Starts with open throttle. Is your mixture screw to far in ? try (systematically) unscrewing it a quarter turn at a time see how it starts. Have you changed jets?

[hazbaz]

Mar 26, 2023 9:08:29 GMT scooterbooter said:

Starts with open throttle. Is your mixture screw to far in ? try (systematically) unscrewing it a quarter turn at a time see how it starts. Have you changed jets?

Yeah. Starts with a fully open throttle

The mix screw wasn’t touched, and the scoot ran fine previously.

I removed and cleaned the jets. But reused them. They were were screwed back in snug.

[scooterbooter]

It's not the scoot I thought it was. I don't know much about them but on autos some times the choke don't work right. Try manually, literally with you hand, restrict the air intake. Does this improve your situation?

[scooterbooter]

Mind you on some autos I've had I've had this but just left it if its still reliable putting down to that scoots particular querk. But really if it didn't do it before it's something you've affected. Sorry dude. Try above...but think ..backtrack.. what could have you affected...... the answer lies within.

[hazbaz]

Think I figured it out….

Checked for leaks. Reseated carb. Same problem.

Remove carb, opened it, checked it over, reassembled.

The mix screw was turned fully out! Clearly the previous owner had a need for speed. Turned it fully in, then 2.5 turns out.

Scoot fired up and is running beautifully! I even figured out that the idle adjuster just presses slightly on the throttle butterfly, so now I know how that works!

It likes E5.

[scooterbooter]

There ya go ! Glad your back on track.