et 250

doober

Member
Nov 30, 2007
383
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ok going old school here. I have a 77-78 et 250 and have a low end bog. i put in a new plug and new belt, but still have the bog. few issues to start with, the screws on the bottom of the carb, roughly to start with how many turns out. the bog i have starts low end, then runs decent for a while, but bogs back out after puttering about for a bit. I am also in need of the carb intake (the thing that looks like an accordion) as the one that i have on there is split badly and could be contributing to me issues. thanks for any input
 

AMAX

Well-known member
Dec 22, 2014
94
73
18
I'm not familiar with the 250 specifically but my first items would be fix the intake, clean the carb (paying good attention to the pilot jet) and check the fuel delivery. I have a 340 I go a few rounds with every year.
 

HANDSOME

Well-known member
Nov 28, 2007
1,400
176
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47
Pouce Coupe
Do you have the airbox on it ? If not try putting it on and see if that helps. Also check engine to chassis ground wire.
 

reignman

Active member
Jan 29, 2009
61
29
18
Boise, id
I could not find a replacement rubber intake part. I used a uni-pod foam intake boot that connected directly to the intake.. I also replaced the carb to a Mikuni and added a single cycliner pump fuel pump. I had a piece welded that connects the carb to the intake.

It took a while, but I got the carb to run ok. There is till issues, but at least the kid can drive it.
 

doober

Member
Nov 30, 2007
383
12
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48
I have taken the airbox out to get the carb off so i could take a look in it, all clean in there from what i could see. But what a pain to get that thing out!! i will check the main ground wire too. I like the idea of using one of those foam filter pods and getting rid of the airbag, mostly because of the hastle of getting the flipping thing out. any specific one i should look for? or are they basically the same. Also will it affect anything on the sled? i don't want to create another issue before i figure this one out.
 

reignman

Active member
Jan 29, 2009
61
29
18
Boise, id
Below are part numbers that I bought thru WPS. If you change the intake to a foam, it might cause it to run a little more lean due to better air flow. I change the carb and added a fuel pump so I didn't just change the intake only. Check the plugs after you change it and see what it looks like.

uni-pod up-6229sa WPS $20
single fuel pump 14-2227
Mikuni vm 34 carb... i found one used.
universal choke 40-3100
jetting for 4k
main 215
pilot 30
needle: second from the top
screw: 1.5 turns I think
 

doober

Member
Nov 30, 2007
383
12
18
48
So now there is another issue, no idea if it is related to the bog or not....got the sled fired up, runs good, but there is a little hold just below the choke on the carb, well it is spitting gas out of that hole, I took the carb apart and looked, just can't figure this out. Any suggestions or more info needed? Thanks for any help, I'm getting pretty frustrated with this.
 

paulharris

Well-known member
Dec 12, 2007
1,337
529
113
Colorado
So now there is another issue, no idea if it is related to the bog or not....got the sled fired up, runs good, but there is a little hold just below the choke on the carb, well it is spitting gas out of that hole, I took the carb apart and looked, just can't figure this out. Any suggestions or more info needed? Thanks for any help, I'm getting pretty frustrated with this.
you need a new needle and seat. your old crunchy needle and seat is not shutting off the incoming fuel and its overflowing out the hole. think of it as a jeweler- you have to pay attention to the very small details and go through the entire carb, or else it will have the last laugh over you. if you dont have the patience, take it to someone who does. Ebay may be your best resource for parts, you may even be able to find a whole carb for a nice price
 

doober

Member
Nov 30, 2007
383
12
18
48
Tried a new needle and seat, still does the exact same thing. One thing I forgot to mention is that we put a primer bulb on it, it's about the size of the palm of your hand and squeeze it a few times before you try to start it, I'm wondering if that is causing to much fuel pressure???? I adjusted the bottom bolt to about a half turn (just trying to get a starting point) and the screw on the side about 2.5 turns out. The diaphragm and all innards in the carb look brand new. The diaphragm is new.