Kettle Clinic

I have recently finished the restoration of my GT250C and when started runs great and ticks over when up to temperature.

However, it is a real p*g to start and generally only manages it on the right hand cylinder on the choke.

Then I need to play with the throttle to get the revs up enough as well as opening the choke, then the LH cylinder fires up.

The carbs have been through an ultrasonic cleaner and all jets, needles etc swapped for new.

Anyone got any ideas.

Firstly can i confirm you have exchanged the jets for genuine Mikuni or Suzuki parts with a number?
Next is to make sure that the throttle is in the fully closed position when trying to start the bike. If the throttle valves are raised at all this renders the choke circuit useless.
I know you say the carbs have been cleaned but it can take several runs through the machine to clean the internal passages.

If it's the carbs with the choke lever only operating on one carb make sure you have the correct bowl on the correct carb they are different.

How do you tell the difference between the float bowls?

One has the choke hole blocked off

Thanks for the help and things to look for. The float bowls were on the wrong carbs (my bad) which was easy to fix and the LH main jet was only a 97 instead of a 97.5.

I’ve replaced the pilot and main jets for genuine Mikuni parts and then started the bike on the choke. It immediately revved up to approx 5000 rpm and stayed there even when off the choke.

The high revving was sorted by putting as much slack as possible in the throttle cable even though the bike ran and ticked over before I changed anything. After that the bike revs dropped and it stalled, then I synchronised the slides again and reinstalled the air box.

All it took then was a few turns of the idle screws and it now starts great and idles nicely.