125cc Choke - is something wrong?

[funinacup]

Got our Moto Roma SK125 today and all working well except the choke, I think.

It has three positions. When in the highest position, or fully on, works fine, high revs. Middle position or half choke, works fine, slightly lower revs, when in the off position the bike cuts out even after a long run (20mins).

Any ideas?

Thanks

Michael

[Joeman]

No need for choke once the engine is warm. If you need choke to keep the motor running you probably need to adjust your idle screw until you dont need choke.

[eastanglianbiker]

Is the bike new or second hand and is there warranty on it? If there is don't mess about with it to much untill you have spoken to whoever sold it to you.but check near throttle and see if there is an adjuster there with lots of play in cable and adjust if you can

[funinacup]

Second hand bike. Will have a look at the idle screw. Cheers!

[Guest]

As joeman says mate,

The choke raises the revs, so in your case, keeping it running, and as soon as you turn the choke off, the bike dies because the idle isnt set high enough to keep it running on its own..

Turn the idle screw it 1 turn, and try see if it idles without choke.,

you want to aim to get your engine to idle at around 800rpm without choke

[funinacup]

So with choke fully off (I am assuming this is in the UP position) I can't get the bike to idle at all. Increasing the revs loads still doesn't help.

I have managed to lower the revs while in the middle position to around 1.5k so it's a bit better but still concerned. Any advice appreciated.

[Joeman]

Jets need cleaning maybe?

[GazW]

So with choke fully off (I am assuming this is in the UP position) I can't get the bike to idle at all. Increasing the revs loads still doesn't help.

I have managed to lower the revs while in the middle position to around 1.5k so it's a bit better but still concerned. Any advice appreciated.

 

You sure it's not the other way round? Choke off is normally away from you and on is towards you. Has been on all my previous bikes anyway, handlebar mounted and directly on the carb.

[funinacup]

So with choke fully off (I am assuming this is in the UP position) I can't get the bike to idle at all. Increasing the revs loads still doesn't help.

I have managed to lower the revs while in the middle position to around 1.5k so it's a bit better but still concerned. Any advice appreciated.

 

You sure it's not the other way round? Choke off is normally away from you and on is towards you. Has been on all my previous bikes anyway, handlebar mounted and directly on the carb.

 

Interesting Gaz...so assuming that's the case - why won't my bike idle with the choke on full? I would expect it to idle at high revs but it just cuts out...

[Mr Fro]

Interesting Gaz...so assuming that's the case - why won't my bike idle with the choke on full? I would expect it to idle at high revs but it just cuts out...

You can have too much choke!

Is there not a destruction manual with it?

[funinacup]

Nah no manual. Too much choke makes sense. I guess the fuel mixture and idle speed needs reset.

[Grumpy Old Git]

Nah no manual. Too much choke makes sense. I guess the fuel mixture and idle speed needs reset.

 

G@@gle is your friend!

Or, get yourself a manual.

[GazW]

So with choke fully off (I am assuming this is in the UP position) I can't get the bike to idle at all. Increasing the revs loads still doesn't help.

I have managed to lower the revs while in the middle position to around 1.5k so it's a bit better but still concerned. Any advice appreciated.

 

You sure it's not the other way round? Choke off is normally away from you and on is towards you. Has been on all my previous bikes anyway, handlebar mounted and directly on the carb.

 

Interesting Gaz...so assuming that's the case - why won't my bike idle with the choke on full? I would expect it to idle at high revs but it just cuts out...

 

It won't do unless it's needed, a choke works to stop an effect, where vaporised fuel droplets stick to the inside of a cold engine. When this happens, it reduces the concentration of fuel in the mix making it harder to ignite. All a choke does is reduce the air that can get through, (chokes it) increasing the concentration of fuel in the mix and making it combustible again. if your bike will start with no choke or on 1/2, it will cut out on full. It's not needed, you're just making it run extremely rich. Enough so that it cuts out.