Suzuki GN125 wont start if cold but starts when push started

[madmadi]

Hello again guys,

Just an update, bike starts every time now

One more question. When I ride fast (if you can ride fast on 125 ) around 50 mph there bike is like braking, choking or something as if it would not get a fuel or spark. It happens only on 4th and 5th gear and on above 6000rpm. When, while riding, I open the choke it seems to help a little.

My theory is that maybe the engine/carb getting some extra air? The air/fuel mixture is set up as originally and apart from that I have only adjusted a little the float previously but put it back to original position.

So, three options here in my opinion:

Air/fuel mixture

Float level

Extra air from somewhere

What do you think?

[eastanglianbiker]

i would start by putting the air fuel mixture back to wher it was before you changed it and see how it is then

[madmadi]

i would start by putting the air fuel mixture back to wher it was before you changed it and see how it is then

 

done. By the manual it should be 2 turns out. I tried 2 and 2.5 and no change

[madmadi]

Hi guys,

Just an update and another question....

Bike starts every time now, there was a problem with electricity, wet cables etc. So now it is fine.

BUT

Now when I ride more than 40mph sometimes the bike is "choking" like the fuel would be cut off for a moment, like you would hit a brake. I noticed that the it is worse when is windy.

Is is possible that the carb takes some extra air (it would explain why is choking when is windy) or maybe there is some problem with electricity and when riding fast the spark is weaker? I check on two different spark plugs and two spark plug caps and there is still a problem.

The thing is that this choking started after I took out the carb. The only two things I have changed are fuel/air mixture and bended a little float so it closes earlier (thought before that the engine won't start because too high fuel level in the carb)

I have changed the air/fuel mixture few times, every time just a little but it doesn't help. Also, recovered float lever to original state.

Any idea guys?

Again, my theories are:

- carb takes some extra air when riding fast - but the question is, through where the air is coming to the carb?

- the spark is weaker and is breaking when riding fast (more resistance in the engine?)

- rings are weared and/or compression is wrong - but it is not really possible as the problem started after dissembling the carb

Thanks in advance,

All best

Martin

[Roadtorque]

Two things come to mind, first is the starter turning the engine fast enough,, second is the plug spark strong enough,, bad plugs fail to produce a good spark under engine pressure,, taking it out & holding it against the engine to see if it sparks, is a waste of time,,,,,,,, A bit more from the history of Bollox from RT

[Fozzie]

Yep, its running lean and from the sounds of it when its at speed so your main jet is the problem.

Clean out the carb, set back to factory and if it still does it then try and upjet a few sizes. The plug should be fouled anyway by running lean but check and tell me what colour it is

[madmadi]

Yep, its running lean and from the sounds of it when its at speed so your main jet is the problem.

Clean out the carb, set back to factory and if it still does it then try and upjet a few sizes. The plug should be fouled anyway by running lean but check and tell me what colour it is

 

Hi mate,

Plug colour is good, creamy white inside.

I have adjusted the carb float a little so it closes the fuel earlier and it seems that it is better now, not so strong choking like before but still a little. Will adjust it a little more.

[Fozzie]

Can you upload a picture of the plug? If there is white deposits on it then it is deffo running lean.

The only time I got a little 125 to hop like that I'd left the choke on and it had warmed up so was running lean. If the plug is overly brown its rich, if overly white its lean.

If lean which I suspect it is you need more fuel getting into the bike. Set everything to default factory setting, I wonder if your main jet is partially blocked?

[madmadi]

Can you upload a picture of the plug? If there is white deposits on it then it is deffo running lean.

The only time I got a little 125 to hop like that I'd left the choke on and it had warmed up so was running lean. If the plug is overly brown its rich, if overly white its lean.

If lean which I suspect it is you need more fuel getting into the bike. Set everything to default factory setting, I wonder if your main jet is partially blocked?

 

Don't have the picture of the plug right now but I know it's ok.

I have adjusted the carb float a little so it cuts off the fuel earlier and it seems it is better now, still choking but not so hard like before. It is definitely something with the carb as the problem started after disassembling it.

[eastanglianbiker]

the air mixture screw would normally be set round about 1 1/2 to 2 turns out from the factory if you havent moved the needle clip then it shold still be set about that

[madmadi]

the air mixture screw would normally be set round about 1 1/2 to 2 turns out from the factory if you havent moved the needle clip then it shold still be set about that

 

Tried from 1 - 3 turns, nothing changed, so it is not that. I think is something with the float....

[eastanglianbiker]

then you need to remove the carb again from the bike take the float bowl off and measure the distance the float tag moves before shutting off the fuel supply this distance should be shown in the haynes manual

[madmadi]

then you need to remove the carb again from the bike take the float bowl off and measure the distance the float tag moves before shutting off the fuel supply this distance should be shown in the haynes manual

 

Will do mate, thanks for that. I adjusted it without measuring it...

[madmadi]

I have attached a photo of my plug. Please advise if it is good.

Now, one more thing. When I adjust the air/fuel mixture screw- when I turn it IN the engine is slower when there is one turn out from the bottom, but from 1.5 turns out until the max out nothing changes. Is it normal?

http://tinypic.com/view.php?pic=jqs028&s=6

[acting_strange]

I have attached a photo of my plug. Please advise if it is good.

Now, one more thing. When I adjust the air/fuel mixture screw- when I turn it IN the engine is slower when there is one turn out from the bottom, but from 1.5 turns out until the max out nothing changes. Is it normal?

http://tinypic.com/view.php?pic=jqs028&s=6

 

Yes this is normal.....dont screw it any further out than 2 turns.....is the needle adjustable?

[madmadi]

I have attached a photo of my plug. Please advise if it is good.

Now, one more thing. When I adjust the air/fuel mixture screw- when I turn it IN the engine is slower when there is one turn out from the bottom, but from 1.5 turns out until the max out nothing changes. Is it normal?

http://tinypic.com/view.php?pic=jqs028&s=6

 

Yes this is normal.....dont screw it any further out than 2 turns.....is the needle adjustable?

 

which needle you mean?