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400 carb questions

16312 Views 8 Replies 4 Participants Last post by  jer400
Hey I just cleaned and put a carb kit in foreman 400 and now its running lean. I assume its running lean because it runs great with the choke on. Anybody got any suggestions? How should the jets be set? If anyone can help me out I would really appreciate it. Thanks S. Masson
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what kind and what size jet did you put in it? also why did you rejet?
Ok i bought a carb kit from quad boss thats supposed to be stock. I just put a carb kit in it because the carb was dirty from trash in the tank because it had set up for a long time. I dont know what size the jets are? I assumed they were stock. Im sorry but im not very knowledgeable in this area. I pulled it down and soaked everything in chemtool carb cleaner. Then I put in all the the new jets, needle, seat and o rings but it did not come with any instructions and I dont have the service manual for this bike. Man im not even sure where to start. The only thing I know is that it runs good will idle smoothly with the choke on. This makes me think it is running lean??? And when i say it runs "good" I mean that it is smooth but it doesnt have the power that it should? I would appreciate any help. Thanks again S.Masson
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if it is running fine with the choke closed your not getting enough fuel. check your fuel line also to make sure your getting a good flow to the carb. you might want to pull the carb again and double check the main jet. try using carb or brake cleaner with the straw on it and blow through all the ports to make sure they are not plugged. The main jet should be a #130, the e-clip should be in the middle grove of the needle, also the air/fuel mixture should be out around 2.5 turns out. these are all factory settings for a stock bike.
Hey thanks alot. All good information. I have a feeling that I dont have something set correctly. I appreciate your time and info. Im at work tonight but Im gonna pull the carb off in the morning and check everything you mentioned. Thank you again. S.Masson
Well I had a chance to pull the carb off of it and check everything today. The main jet is a 130...the air/fuel mixture screw is backed out 2.5 times. Its getting plenty of fuel. It still runs bad. Just for grins I changed out the main jet with the old one and it runs the same. I cant figure it out. It runs decent with the choke on but wont accelerate at all with it off. Im not sure but I may have to take it to the shop. Its got me stumped.
When I installed my Dyno Jet kit my bike was doing the same thing. It would run better with the choke on or covering half of the intake. I ended up having to put an aftermarket exhaust so it could breath better. Not sure if this will help you but that's what happened to me. Also I assume the bike was running ok before you started servicing the carb?
nishjg is right, it may not be able to breath. the exhaust may be plugged. you can try removing the muffler and see if it runs better.
I thought Hondas dont runn with out muffler becuase they need that back pressure
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