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Carb Guru's, Is 1/4 fuel turn wrong.

W
Dec 25, 2011
73
16
8
index wa
Ok, Her is the deal. Trying to dial in my carb and I went all the way down to 1/4 turn to get rid of my wot bog, which it did but I still have a low end bog that seams to be to rich. Can this damage it anyway, seems like its getting enouph gas from somewhere?

Its a 2006 600ho RMK

The low end clears up after a second or two and then runs great thru the whole range, it especially bogs after slowing down and letting it basicly idle for a few seconds like when your sizing up your hill climb just before commiting too it. At times I have to shut it off for a few seconds then when I start it up get on the pipe quick and it clears up. If I don't get on the pipe right after starting it will bog out so much clutch won't engage.

(I had it at 1/2 turn and it nearly worked but there was definitely a top end studder, moved it to 1/4 and it went away)

Recently replaced the reeds.
Cleaned carbs twice.
Confirmed with local dealer that my jetting is correct for the altitude I ride at 3-6000 feet.

All stock
Main is a 330
Pilot is 50
clip is at position 2
air jet is a .6

I'll probably move the clip up to the top so I can have a bit more fuel BUT I'm concerned that factory setting are not working ??

Anyone else have a similar situation where stock settings just don't work.

I've read many are going with a .9 or 1.0 air jet but most are working with a main just of 400 and I'm down to a 330, could just changing this jet help?
 
Last edited:

Super Dave3

Well-known member
Lifetime Membership
Feb 15, 2003
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Klamath Falls OR
Going to a 1.0 air jet will clean up the bottom end issue you speak of. The fuel screw has no influence on the top end bog. Needle and main jet influence top end.
 

retiredpop

Well-known member
Lifetime Membership
Jul 3, 2001
1,350
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Calgary
1/4 turn on fuel screw is not right. You should be around 1.25 turn. You definitely don't want to tune WOT by the fuel screw. I think your problem lies in the fuel enrichment (choke) circuit. The plungers are probably not fully seated in the bottom of their bore so you are allowing extra fuel through them. You want to have about 1/8" free play in choke cable when choke is off. Jet needle position has an effect on mid range from 1/4 to about 7/8 throttle operation along with the main jet. Raising the clip toward the top of the needle leans out the mixture with #1 position being the leanest. Main jet determines fuel flow from 7/8 to full throttle. Do a search for mikuni carb tuning. Tons of info out there.
 
W
Dec 25, 2011
73
16
8
index wa
Choke not seated sounds like the right answer as the gas is getting in there to burn somehow and looks like the choke is a direct path around the jets. I probably didn't put them in correctly on the last cleaning,

Never had such a temper mental engine before.

Thanks for the input its nice to confirm concepts when your diagnosing as I tend to justify all my ideas wrong or right.

I'm limited to weekends for working on it so I'll checking that 1st thing Fri.
 
D

dotter

Member
Mar 10, 2009
98
14
8
66
Red wing MN
Carb tuning

Fuel screw 1 turn out, should be close, remove and clean all jets, pilot 45, paj maybe .6, then like others said adjust choke, both carbs, good luck
 
W
Dec 25, 2011
73
16
8
index wa
Choke cap

It ended up being the choke.

There is a rubber cap on the top of the plunger and it had lifted up preventing it from closing all the way.

It was just barely lifted but enouph to cause most of my troubles.:brick:
 
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