the lever on top of the left carb. which way to turn the choke on. push down? or pull up?

 

On is usually always up... off is usually always down, on carbed bikes

 

you are talking about the plugger itself not the lever connected to the plugger correct? i'm a bit confused

 

Try starting it with the lever fully one way...if it works it's most likely open. If not, try 1/2 way between the two positions. If still no worky, try full the other way. It ain't rocket science.

If you can't get it to work, I'll buy the RD of you for $100

 

i think the 250's use similar Mikuni's to those in my 400, in which case, you push the tab/lever down to turn on the choke. (that pulls the choke up).

 

THANKS that's what i thought. it seems to run better lever up which pushing the plugger down.

 

I hope you're only using the choke to warm the bike up. You don't want to be using the choke for more than a minute or two, and definitely not riding it with the choke on, either.

 

i'm soooo confused. i really need to take photos.

here is what is happening with this bike. the bike runs great for a few days then one or two of the cylinders just stops running. the culprit i find out is that somehow the plugs are fouling.

so i think the oil injection system is malfuntioning. so i bypass that is just run premix. it runs better but now it seem to dies while i'm coming to a stop and pulling in the clutch. what could that be? i set the idle at 1500-1700 rpms.

okay let me know if i'm right or not. when the bike warms up i push down the coke lever and the bike's rpms drops. like to 1200-1500rpms. does this mean that i just turned off the choke? on the contrary when i lift the lever up the rpms rises 16-2000 rpms. does this mean the choke is on? or the opposit?

 

Carbs a guillotine type... that means when you raise the slides, that is opening or enriching the circuit. so it is up. if your lever is hinged in the center, that would reverse the movement... usually most carbs OFF IS DOWN... that way you can not mistakenly push or hit the lever down, the direction of gravity, and be riding around fully enriched with the choke on

 

op:

choke on = revs up @ idle
choke off = revs down @ idle

 

It's weird to me that your rpm's are dropping when you press down on the choke (which turns it on).

how's your jetting? any mods?

 

no mods. completely original.


yeah it's weird too me also.

i'll take a photo real quick and see if i can better explain this.

 

here is a few photos. please point out which way is choke on and choke off. thanks.



above is the choke lever. it is connected to the plugger below

 

1st pic = choke ON
2nd pic = choke OFF

 

hey guys thanks for the clear up.


after figuring out the carb choke issue and such i ran into another problem.


the left cylinder is not firing. and i found out that at the points on the ignition it is arcing brightly of the left side.

the right side fires fine and the points for this cylinder is firing fine with no, too very little signs of arcing.

what could be wrong?

i have tried swapping the two points and the problem is still there. let me know what i can do.

or if you guys have no idea is there a vintage yamaha forum i can go to?

 

go to usa2strokers.com. not a very busy forum, but all the guys there are very crotchety and knowledgeable.

as far as your points--have you checked spark for the left cylinder at the plug? the arc'ing imo, should be happening (at least between the points). if the left cylinder is not firing, i'd troubleshoot the coil and associated wiring.

clean and reset your gap while you're at it. or, get a newtronics electronic ignition and be done with it