Choke question on Mikuni carb (250cc)

jcurrieta · 03-19-2012, 10:46 PM

'06 250cc bike has a mikuni carb and doesnt like to idle when cold... also lots of popping out the exhaust.
I just got the bike like this and the choke cable is disconnected,,, can someone explain the operation of the choke (what is on and off like)

The black lever will travel down intern pushing the metal thing up (im guessing this is "on") But when i push the black lever back to off the metal piece stays where it was. is this normal? Whats the function of that metal part?

Weldangrind · 03-19-2012, 11:01 PM

Welcome!

A pic would help, but I'll take a stab at it. Without a cable, the black lever (on the carb) is up when the choke is closed, and down when the choke is open. There are usually three detent positions that provide open, closed and a mid position. There is a very light spring on the choke door, and it will be easily overcome by engine vacuum if you crack the throttle.

When you use a cable, there is a spring that is placed behind the black lever (mounted on the carb), that helps the cable maintain position. With a cable, there are no detent positions, so you can choose how far open or closed the choke is.

Make sense?

jcurrieta · 03-22-2012, 01:13 AM

got the carb off and was looking it over,,, the door isnt spring loaded on mine,,, wonder if its broken,,, where is the light spring?? I do have 3 detent positions on the black lever tho.

Weldangrind · 03-22-2012, 02:44 AM

You can't see the spring unless you remove the choke lever shaft (don't bother). If you close the choke with the lever, you should be able to push the door open and have it spring shut when you release it.

jcurrieta · 03-23-2012, 03:47 PM

that must be my issue,,, my choke door isnt spring loaded,,, if it was it musta broke off. crap i just put the bike all together,,, now i have to take the carb off again. wtf,,,, anyhow thanks

jcurrieta · 03-23-2012, 08:59 PM

... so what do these engines like when you start them cold,,,, full choke or half choke??
Its not starting,,,, I'm either not giving it enough choke or too much choke?

Also is it normal for it to be pushing alittle gas out the brass tube with the hole in the side of it (im guessing is the air vent)?? it only comes out when im kicking it over?

Weldangrind · 03-24-2012, 02:19 AM

I've never noticed fuel coming out of a vent tube while kicking over, but I've never looked that closely. I just checked a new Mikuni I received today, and the choke door is definitely sprung. I'm starting to wonder what type of carb you have.

May we see a pic?

jcurrieta · 03-24-2012, 10:54 AM

i def. have the fake mikuni pz30 carb,,, it is identical to the one shown on the gio bikes site shown here: http://www.giobikes.com/Performance-...buretor-250cc/
Im guessing my spring door is missing or broken off,,, where is it located on your carb?? inside somewere or on the outside??

Weldangrind · 03-24-2012, 11:30 AM

To be clear, your carb is either a PZ30 or a Mikuni. A PZ30 is a clone of a Keihin. How many float bowl screws does your carb have?

My choke plate looks just like the one in this Gio pic; the spring can't be seen, because it's located under the cap on the left side, and it rides on the shaft that the choke plate is mounted on:

jcurrieta · 04-06-2012, 08:07 AM

it reads mikuni on it like the one in the pic,,, i know its a fake mikuni but that's what i call it cause it reads that on it (I heard they did that to avoid being sued)......it has 4 float bowl screws... ill have to go check that spring out thanks.

FLASHLIGHTBOY · 04-15-2012, 11:57 AM

Who is going to sue the Chinese manufactor???? no one can do that to them... it is a free country for them to make things like that.. if you buy from a unknow seller.. you might get one..

03-19-2012, 10:46 PM	#1
jcurrieta Join Date: Mar 2012 Posts: 21	Choke question on Mikuni carb (250cc) '06 250cc bike has a mikuni carb and doesnt like to idle when cold... also lots of popping out the exhaust. I just got the bike like this and the choke cable is disconnected,,, can someone explain the operation of the choke (what is on and off like) The black lever will travel down intern pushing the metal thing up (im guessing this is "on") But when i push the black lever back to off the metal piece stays where it was. is this normal? Whats the function of that metal part?
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03-19-2012, 11:01 PM	#2
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	Welcome! A pic would help, but I'll take a stab at it. Without a cable, the black lever (on the carb) is up when the choke is closed, and down when the choke is open. There are usually three detent positions that provide open, closed and a mid position. There is a very light spring on the choke door, and it will be easily overcome by engine vacuum if you crack the throttle. When you use a cable, there is a spring that is placed behind the black lever (mounted on the carb), that helps the cable maintain position. With a cable, there are no detent positions, so you can choose how far open or closed the choke is. Make sense? __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
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03-22-2012, 02:44 AM	#4
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	You can't see the spring unless you remove the choke lever shaft (don't bother). If you close the choke with the lever, you should be able to push the door open and have it spring shut when you release it. __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
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03-24-2012, 02:19 AM	#7
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	I've never noticed fuel coming out of a vent tube while kicking over, but I've never looked that closely. I just checked a new Mikuni I received today, and the choke door is definitely sprung. I'm starting to wonder what type of carb you have. May we see a pic? __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
	0

03-24-2012, 11:30 AM	#9
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	To be clear, your carb is either a PZ30 or a Mikuni. A PZ30 is a clone of a Keihin. How many float bowl screws does your carb have? My choke plate looks just like the one in this Gio pic; the spring can't be seen, because it's located under the cap on the left side, and it rides on the shaft that the choke plate is mounted on: __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
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03-22-2012, 01:13 AM	#3
jcurrieta Join Date: Mar 2012 Posts: 21	got the carb off and was looking it over,,, the door isnt spring loaded on mine,,, wonder if its broken,,, where is the light spring?? I do have 3 detent positions on the black lever tho.
	0

03-23-2012, 03:47 PM	#5
jcurrieta Join Date: Mar 2012 Posts: 21	that must be my issue,,, my choke door isnt spring loaded,,, if it was it musta broke off. crap i just put the bike all together,,, now i have to take the carb off again. wtf,,,, anyhow thanks
	0

03-23-2012, 08:59 PM	#6
jcurrieta Join Date: Mar 2012 Posts: 21	... so what do these engines like when you start them cold,,,, full choke or half choke?? Its not starting,,,, I'm either not giving it enough choke or too much choke? Also is it normal for it to be pushing alittle gas out the brass tube with the hole in the side of it (im guessing is the air vent)?? it only comes out when im kicking it over?
	0

03-24-2012, 10:54 AM	#8
jcurrieta Join Date: Mar 2012 Posts: 21	i def. have the fake mikuni pz30 carb,,, it is identical to the one shown on the gio bikes site shown here: http://www.giobikes.com/Performance-...buretor-250cc/ Im guessing my spring door is missing or broken off,,, where is it located on your carb?? inside somewere or on the outside??
	0

04-06-2012, 08:07 AM	#10
jcurrieta Join Date: Mar 2012 Posts: 21	it reads mikuni on it like the one in the pic,,, i know its a fake mikuni but that's what i call it cause it reads that on it (I heard they did that to avoid being sued)......it has 4 float bowl screws... ill have to go check that spring out thanks.
	0

04-15-2012, 11:57 AM	#11
FLASHLIGHTBOY Join Date: May 2009 Location: SASKATOON Posts: 1,161	FAKE MIKUNIS Who is going to sue the Chinese manufactor???? no one can do that to them... it is a free country for them to make things like that.. if you buy from a unknow seller.. you might get one.. __________________ DEALER FOR ZSTAR & GIO PRODUCTS, TAOTAO ABIBABA ATV ETC
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