Gz125 High revs with choke open - Please Help :)

[RubyBones]

Hi all, 

 

I’m new to it all and thought I had an idea what I was doing but it al seems a little overwhelming now since getting my first bike. 
 

bought myself a nice little gz125 Suzuki marauder. Been running since I got it beautifully and got me back 3 on my first ride 3 hours from pick up to home.

 

Bike has been starting in the button every time, however I have been starting the bike with the choke closed. It’s not been cold so didn’t think I had to even when not used for few days. No issues so far, but someone said I should be starting the bike from

cold every time with the choke open. 
 

So I tried but when j start the bike with choke fully open (basic pull/push choke) the revs are high, not dangerously high but way above normal idle and it doesn’t seems to settle down either. 
 

1st questions, is this Normal, due to the air intake from having the choke open and should just be waiting few mins and then riding the bike with the high revs and then closing the choke shortly after. 
Or am I looking at possible vacuum leak in the carb boots maybe 

 

2nd question is, after starting the bike with the choke open I went for ride and the for first time ever, twice when I hit around 45mph, bike started jerking and loosing power before loosing all power. 
 

pulled over and started bikes again no issues and off I went. 
 

is this related or could this be something else? 
 

I thought maybe I’d be an idiot and not fuelled up so switched to reserve. Seemed to be fuel in the tank in either side so could not imagine was the case

 

can anyone help/advise 

 

Question 3. do I need to/should I try adjusting idle speed while choke open to bring down the revs or is idle speed only to be adjusted with choke closed?  If to be done when open surely this will drop the revs to below idle and likely cut engine when i close the choke? 
 

sorry for so many questions, just so little info I can find out there 

 

thanks everyone

[Mississippi Bullfrog]

Ah - takes me back to the good ol' days when most engines has manual chokes.

 

First thing is that many four strokes will start without choke unless it's cold. My Honda never needs choke during the summer. It's just beginning to need it on cooler early morning starts. You will get to know when it is needed or not. If in doubt try without first. The advice to always use the choke is wrong. Only use it if it's needed.

 

When you use the choke it usually does two things - richens the mixture and increases the idle speed. So the rpm should be higher when the choke is used. This enables a cold engine to run the richer mix.

 

With most bikes you can push the choke in pretty quickly. Even on the coldest of days I can push the choke in within a couple of hundred yards of the house. If you leave it open the rich mix can cause misfires particularly at light throttle settings. So try to close it as soon as possible.

 

You only adjust the main idle speed with the choke off - ie with the engine fully warmed up.  You can adjust the choke idle speed if it isn't set right to enable the engine to run when cold, but generally unless that's not working leave it alone.

 

On a cold day I usually fire the engine and let it warm up for a minute or two before I set off.

[Bianco2564]

Hello and welcome.

Was just writing a reply when MB beat me but echo everything said.

Having a bike or car with a choke takes a bit of getting used to to find the best setting for if the engine is hot or cold and what the ambient conditions are like.

My carbed R1 in summer needs half choke to start from cold, in winter full choke, either way I can switch if off after 100 yds or it runs like a pig.

My 380 choke is similar to your bike I think, its either on or off, no regulation so it starts and revs to 2500rpm until I can hear it start to start chugging because the mixture is too rich, then flick the choke off.

 

 

[RubyBones]

Can’t Thank you enough @Mississippi Bullfrogand @Bianco2564 , exactly what I needed to hear. So glad I joined the forum

[bonio]

The choke is there to help the bike start on cold days. If the bike starts without it, that's  great: don't use it. If you need to use it in the winter, usually a couple of minutes is enough before you can go back to normal running. 

 

On my drz, if its cold, I pull out the choke, start up, and leave it running while I faff about with my helmet and gloves. When I hear the engine speed up a bit I know it's warming up, so I push the choke in, jump on and ride off. 

 

You'll get to know by the sound of the engine when you need the choke and when to put it in.

[RubyBones]

Thanks also @bonio  Great stuff to hear.