2003 Honda 400ex - Help!

[trodge400ex]

i have a 2003 400ex. when i got the atv it had a 40cc big bore kit but i went back stock because it was knocking. i put a new carb with stock jets. when im riding in first gear and and shift and get on the gas the quad wants to bog. it has no low end torqe what so ever. it also has a new plug. idk if it has something to do with the valves or what. idk where else to look.

thanks.

[oxidized_black]

there are alot of guys here that have ex's and can probably steer you in the right direction. before you put it back to stock, was the low end torque there?

[marioweldinginc]

A member named CK_1999 would be the best guide. He knows EXs inside and out. Also ask Cheriah she is a wiz when it comes to carb problems

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[trodge400ex]

im not sure i bought it from the guy with it knocking so i never got to ride it before.

[marioweldinginc]

What did you set the carb at. Clip position etc, # of turns

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[trodge400ex]

its turned about 1 1/2 turns and the clip postion is the 3rd one.

[marioweldinginc]

The slow jet is a #38 is that what you have? Main is #148 but i dont think that circuit is the problem. Pilot screw is 2.25 out.

Maybe you have some dirt in the carb too.

If you have the room do a slow speed plug chop.

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[trodge400ex]

thanks i will try that. yea its a 38 main and a 148 slow jet

[trodge400ex]

i think it has a stage 2 cam in it also. could that have anything to do with the no low end power?

[marioweldinginc]

I dont think so.... 400ex should have some low end grunt. How does it pull mid to wot? Does it feel like the clutch is slipping?

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[CK1999_400ex]

if yu are still running the stage 2 cam you will need more fuel to get it to run properly ... i would up jet a few sizes and see how that does ... with the stock jets its going to be running lean with that cam and will also run hot and cause it to ware the rings out ..(the rings will get hot and will lose there temper and then not be as stiff and will let it lose compression and then it will start smoking ) burning oil way sooner than it should from normal riding ..i learned that the hard way when i was building and running several different motors in the same 400ex for different races and hill climbs and dirt drags ...i was always useing the same carb .. and needed a different jetting for each motor ..of wich i finally did after wareing out rings several times ..

[marioweldinginc]

Thanks ck for smacking me in the head I didnt put 2 and 2 together... Factory jetting with stage 2 cam...i have to stop working 3 jobs

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[CK1999_400ex]

lol... its ok mario ..lol... ill let ya slide this time ...

[trodge400ex]

once it gets out of low end bog it will fly. mid to high rpms it runs like a champ. the clutch feels strong

[trodge400ex]

i hade a 150 jet in it and it ran even worse

[marioweldinginc]

Dont worry bout the main jet that fuel circuit isnt the problem. I think the problem is the pilot circuit. The screw should be out 2.25 from light seat. Did you try that?

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