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Carb help please.
Posted: Sat Jan 17, 2009 8:57 am
by krisrtch
I'm working on a 04 Yamaha Kodiak 400 for a co worker. I've gone through the carb and cleaned every orfice and jet. Put fresh gas in it. But yet upon running it I can only get half throttle. If i try to open it up it just sputers and tries to die until i butterfly the throttle. This thing has a Mikuni carb with some funky diaphram on top the needle which is in good conditon . I adjusted the fuel screw to 1 3/4 from 3 turns out. It fires right up and idles ok but just nothing up top. Anyone have any ideas what might be going on?
TIA
Posted: Sat Jan 17, 2009 9:17 am
by Asmith
What model number Mikuni?
Posted: Sat Jan 17, 2009 9:28 am
by krisrtch
Posted: Sat Jan 17, 2009 11:17 am
by krisrtch
i just don't understand what is going on with it. It idles no problem whatso ever. Up to half throttle runs good. But then it just falls flat on it's face past that.
Posted: Sat Jan 17, 2009 1:23 pm
by Canuck
Make sure the spring in the slide is in 1 piece, if the spring is weak, the diaphragm will raise sooner allowing more fuel to come up the needle jet. Check the diaphragm for holes as well.
Posted: Sat Jan 17, 2009 4:18 pm
by krisrtch
Diaphram is is good condition no holes. I'll double check the the boot tomorrow.
Posted: Sat Jan 17, 2009 4:31 pm
by Canuck
Pay real close attention to the jet that the needle slides up and down in. I have seen these wear larger with little wear on the needle. Take the needle jet out of the carb and insert the needle into it. Take a little lite and shine it up from the bottom of the jet and you will see if the hole is a little oblong. If you have a needle that is a little larger, you can see the oblong wear easier. There is enough room for the needle to go right thru.
Posted: Tue Jan 20, 2009 6:37 pm
by krisrtch
Well come to find out after pondering for 2 days WTH was going on. I was over looking the break down again and after thinking of what it was doing. I realized I completly missed the main jet which was in the throat of the filter side of the carb.WTH??? No wonder why i missed it. With that thing having four jets it threw me all off. Cleaned it up and VVVAAAROOOMMM away it went all fixed. Thanks all.
Posted: Wed Jan 21, 2009 12:40 pm
by Canuck
At least you found the problem before buying lot o parts.