Tell me what it means...

[Ragingrob]

If when I start my bike it starts fine with no choke when not cold, but if I throttle back from idle it loses all power and cuts out...? Fuel blockage problem? Is anyone keen to show me how to check things such as jets and lines in the carb? Or is it something else?

Cheers

[nadroj]

How do you throttle back from idle? Choke richen's the mixture by restricting the airflow thru the carb when cold. As it warms it can then be leaned by turning the choke off.

[Ragingrob]

I mean pull the throttle back from idle, as in rev hardout (well it cuts out). I'm doing this with the choke in the whole time, it's as if when I try and rev lots from idle it gets starved from enough fuel or something...

[tri boy]

Sounds like water in fuel bowl, or blocked main jet.
Drain bowl, and try again.

[Ragingrob]

As in just open up the tank at the top and throw away all the petrol, then put new petrol in and see if it fixes it?

[tri boy]

As in just open up the tank at the top and throw away all the petrol, then put new petrol in and see if it fixes it?

Nah. Try this:
At the bottom of the carburettor bowl, there is a small screw that allows the bowl contents to be drained. Turn off the fuel tap at the tank.
l
Loosen/remove the screw at the fuel bowl, and allow the petrol to drain out of the bowl. (about an eggcup worth of fuel). It helps to put a container or rag below the carb to catch/absorb the fuel.
Tighten the screw up, and turn the fuel tap on again.
It takes a few seconds for the bowl to fill, so use the time to disspose of rag etc.
Wipe up any spills, an start the bike.
See if that will solve the fault.
(if your carb has no drain screw, I suggest you get a mechanic to help).

[HTFU]

sounds pretty normal for a GN when warming it up. From new I could never give it more than idle throttle until it was warm regardless of choke used or not. This got worse over time, as it became harder to find the right amount of idle without cutting out, until I had the valve clearance done and it was like new again.

I thought you had sold that bike?

[surfer]

Nah. Try this:
At the bottom of the carburettor bowl, there is a small screw that allows the bowl contents to be drained. Turn off the fuel tap at the tank.
l
Loosen/remove the screw at the fuel bowl, and allow the petrol to drain out of the bowl. (about an eggcup worth of fuel). It helps to put a container or rag below the carb to catch/absorb the fuel.
Tighten the screw up, and turn the fuel tap on again.
It takes a few seconds for the bowl to fill, so use the time to disspose of rag etc.
Wipe up any spills, an start the bike.
See if that will solve the fault.
(if your carb has no drain screw, I suggest you get a mechanic to help).

Best to drain this into a little container so you can see if there is any water in there. You will spot the water easily if there is any.

Does it start ok with a warm engine and the choke off?

If the answer is 'yes' your problem might just be that you need the choke on when the engine is cold. As when you start your bike from cold you may be flooding the engine by pulling back on the throttle hard as it has not warmed up enough.

Good luck. Let us know what you find.

[Ragingrob]

sounds pretty normal for a GN when warming it up. From new I could never give it more than idle throttle until it was warm regardless of choke used or not. This got worse over time, as it became harder to find the right amount of idle without cutting out, until I had the valve clearance done and it was like new again.

I thought you had sold that bike?

I thought I had too , sale fell through . Hmmm it starts fine with no choke even 5 mins ago, so it was pretty cold after 4 hours of just sitting in the garage... I guess it could just be not warmed up and therefore flooding when opening the throttle?

[Ragingrob]

Nah. Try this:
At the bottom of the carburettor bowl, there is a small screw that allows the bowl contents to be drained. Turn off the fuel tap at the tank.
l
Loosen/remove the screw at the fuel bowl, and allow the petrol to drain out of the bowl. (about an eggcup worth of fuel). It helps to put a container or rag below the carb to catch/absorb the fuel.
Tighten the screw up, and turn the fuel tap on again.
It takes a few seconds for the bowl to fill, so use the time to disspose of rag etc.
Wipe up any spills, an start the bike.
See if that will solve the fault.
(if your carb has no drain screw, I suggest you get a mechanic to help).

Hmmm, so where's that carb again? I'm pretty new to the whole mechanics but getting into it! I've emptied the kinda fuel sediment catcher thingy no idea if that would've helped.

But it's starting way better than it was before, still the hole cut out when throttle though, but could just be due to cold engine?

[tri boy]

See if it responds better when its warm. (its normal for a bike to stall/splutter if cold and the choke is in).
As Robignevil said, the valve clearances may need adjusting also.
Sorry can't help much more without being there.
See if you can ride it too a bike shop, so a mechanic can listen/assess it.
Good luck.

[Ragingrob]

Hmmm well I guess it's all good then...as when I rev it slowly and let it warm up then it revs fine. It's just when I start it up I've gotta remember to give it a decent rev and warm up because sometimes when I start riding and get to an intersection it cuts out as I start to head off!

[Shadows]

If when I start my bike it starts fine with no choke when not cold, but if I throttle back from idle it loses all power and cuts out...? Fuel blockage problem? Is anyone keen to show me how to check things such as jets and lines in the carb? Or is it something else?

Cheers

Along with the other suggestions above, another thing you should check out is whether or not your airbox is closed up properly, and that there are no air leaks between the airbox and the carb, or between the carb and the head.
If nothing is obviously in need of tightening, then with the engine idling, spray a little engine start around the airbox and carb connections - if extra air is finding its way in and leaning things out then you'll hear a slight increase in revs as the ether comes through.

[skidMark]

yeah it will bog when cold even my zxr does it...all engines do...just let it warm up...i let mine warm up while i'm brushing my teeth and putting my gear on...with disc lock on...then when i'm ready turn it off......take off disc lock....put keys bakc in ignition...fire her back up..and away i go

[Reckless]

Hmmm well I guess it's all good then...as when I rev it slowly and let it warm up then it revs fine. It's just when I start it up I've gotta remember to give it a decent rev and warm up because sometimes when I start riding and get to an intersection it cuts out as I start to head off!

I don't think you have a fuel problem your just trying to rev the shit out of it b4 its ready.
At start up or when cold never rev a bike hard. The oil isn't warm or up to pressure. It is when most damage or wear is done to any engine.
Secondly you will always have to feather the throttle on a cold bike, especially a carburated one. Thirdly use the choke that's what it is there for.

Most bikes like to start with no throttle and about 1/2 choke leave the choke out a bit till the revs start to climb as it warms up.

Do either what Skidmark said and let it warm up properly then leave or leave the choke out a bit when you ride off. Push it in at the next lights or when you feel the bike responding.

The qualifier is every bike is different you have to find its individual preference I.E. 1/4 choke, 3/4 choke then back to 1/4 after 2 mins etc etc. It doesn't hurt to ride off slowly and take it easy till the engine warms up as your tyres and you are warming to the task as well. Be more careful doing it skidmarks way as you will have an engine thats ready to go like shit and tyres and a brain that are cold as hell.

If the above doesn't work start looking for the problems the others have described.
Good luck!