ET 250 carb

B

Bob Vehring

New member
Joined
Dec 10, 2008
Messages
114
Age
74
Location
Milw. Wi
I have a problem, picked this sled up afew months ago, was a complete wreck looks wise, but ran well. Started easy, idled well, only ran it through the yard to get to the shop. I had the engine out to replace tie rod ends and paint it.
I thought about going trough the carb, I have several other old Yamis but have never seen a carb like this, was afraid I'd need parts and not have them. It was running well so I left it. Long story short, I left it alone. Put the engine last night, now hard to start and dies every time with in 30 sec.
Heres the problem leaving for ER Derby tonight, really want to take this sled.
I have read the thread on switching to a 34 slide, might have enough parts here to do it, but wondering if theres something simple with this odd little stock carb that I'm just missing

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Hi, I just converted my Yamaha 250 after having the same problems as you... I used a VM34 Mikuni, separate fuel pump, jetted to 220 Main, 30 pilot jet. This thing runs better than a new one now. Only problem is you lose your oil injection but I think its worth it overall. Those original 250 carbs are a real pain to work on and very hard to even make adjustments to while on the sled. Replacement parts are nearly impossible to get and very expensive. Most are discontinued from Yamaha. There is a real good recent chat forum on here about the 250 carbs that I learned from. Would recommend it to you if you havent seen it. Good luck...
p.s. Your Enticer is a "Beauty" Good to see them like that.
 
Where can I find a hose routing diagram for these. There are 2 1/4 hose conections on the right side, one for pulse one for gas. I for got to note which is which
 
The gas inlet is usually the 5/16" fitting (larger) and the pulse is the 1/4" (smaller) of the two. Thats how they was on mine... Hope this helps.
 
Does anyone know the "proper" proceedure for adjusting those Keihin ET250 carbs. They have a large bolt / locknut on the bottom, a sight glass on the side so one can see the level of gas in the carb but I dont know what level is right... Would love to find a pdf of the adjustment proceedure on the net somewhere. Can anyone help us? Thanks in advance!!
 
Basically, with a warm engine . . .
  • Loosen the locknut on the fuel regulator screw (the bolt in the bottom)
  • Turn the regulator screw in 6 full turns from just started
  • Start the engine and adjust idle speed to spec
  • Remove the cap from the fuel pipe (sight glass)
  • Turn the regulator screw in to raise the fuel level in the pipe or out to lower the fuel level in the pipe until it is aligned with the top joint of the pump body to carb body
  • Without turning the regulator screw, tighten the locknut
  • Replace the cap
  • Adjust idle mixture, throttle stop, and high speed mixture (if adjustable)
 
Thanks for the help. Really appreciate it. I am told I need to open a bleeder vent too to let air out of the carb. Is that correct?
Thanks again for your help.
 
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