What the...?

[geezus18]

I had a go on my bike a few minutes ago in the backyard and turned the choke off/open (flicked the lever up..i think thats right..its a mikuni carb). I then went to gun it and all the power went away and then the bike took off..it kept happening. If it helps istarted the bike with the choke on then as soon as it got going i flicked it off..do i need to let it warm up at all?

 

[user 2364]

t

 

[Cruzen]

Down = Rideing... Up = Cold Start

 

[geezus18]

Ok, well when i flick the lever up (cold start) the bike nearly stalls but then builds revs back up. It seems that the revs are higher when it is up than when it is down. So is this the reason why when when the choke lever is up or on the cold start position and i go to accelerate nothing happens even when the throttle is completly twisted and then it kicks in all of a sudden and the bike nearly flies out from under me?

 

[geezus18]

could n e one help me out with this???
cheers

 

[Dirt Bikez & Pocket B]

there might be a blockage somwhere of maybe u got crap in the carb, try cleaning it out.

 

[geezus18]

i cant see how my carb could be dirty as i have only used the bike for like an hour and a half all up..ill give it a quick look and also see if it still does it with the choke on the "riding" setting.

 

[Dirt Bikez & Pocket B]

hmmmm seriously i think you should take your bike out 2moro and rev it in neutral a bit, let the bike warm up then take it for a ride and take it easy and gradually pace it up until your at top speed, this should flush out your bikes system and hopefully fix your problem, i have an atomic and riding it hard usully fixes my problems.

 

[geezus18]

cheers ill giv it a crack..hope it works i cant be f*%$ed taking it apart...lol!

 

[geezus18]

I rekkon that when the lever is up its actually the riding setting and when its down thats when its the cold start..ive tried starting it with the lever up and it takes some effort, but when the lever is down its easy. Plus when the lever is up the revs get much higher.
pics in a minute!

 

[geezus18]

DOWN

UP

 

[geezus18]

Could anyone clarify which way is off and which was is on?
reminding that the revs build when the lever is in the up position.
cheers

 

[FLICK]

Up = choke on
down = choke off

 

[No-Fear]

i rkn a blonde would have worked that out!! hahahha

Up = choke on
down = choke off

 

[450Mudman]

Choke !

Pull the Choke on on starting if air temperature is below 26 degrees C
when engine is stone cold. (lever up)

Leave the Choke off when air temperature is above 26 degrees C
when engine is stone cold. (lever down)

When engine has been warm leave it off all the time (lever down)

keeping the choke on during riding can melt down the engine!!!
no engine is designed to run like this, plus it will not rev well.

 

[Mack]

Basically when the lever is up on these carbs it opens a jet which feeds a lot of extra fuel into the engine (richens it right up!) so the revs pick up on idle and starts are easy. If at this point you gas it, even more fuel is pumped in, so you get the hesitation you've experienced. But because these carbs don't have a butterfly choke, more air has come in as well, so when it recovers from the initial stall it wants to bolt. This will happen to anyone with these carby's. Down is the for the normal operation of the carb. Even still, these motors take a few good minutes to warm properly. If you rev right after starting you can damage the cam lobes and followers cause the oil isn't pumped up to the head yet.

 

[Redstar]

More basically, a choke is merely a plate that closes the air passage of the carb. When this is closed, the effect on the fuel/air mixture is that there will be the same fuel content vis-a-vis very little air, thereby resulting to a richer mixture. We need this for cold starts and cold starts only. Once the engine has warmed up in this setting, switch to opening up the choke and you should be able to run properly.

I'm not too sure about a jet opening up to feed lots of extra fuel as Mack has mentioned although the same general function he and I mentioned is what a choke is for.

 

[Mack]

There is no plate or butterfly choke in that carby. See in the picture above the little plunger attached to the choke lever....that lifts a little rod that richens up the mix.

 

[Chukkie07]

Just let it warm up before you ride it. Let it sit for a minute or two just idling...and if it won't idle (my old cr80 wouldn't) just blip the throttle to keep it alive every once in a while...

 

[Redstar]

There is no plate or butterfly choke in that carby. See in the picture above the little plunger attached to the choke lever....that lifts a little rod that richens up the mix.

Ah-huh.....you're absoultely right. I obviously didnt pay too much attention on the blurry pic(!). Thanks for the correction. The info served me as well.