[Spiting/sputtering 416] - ATV Riders Forums - Honda, Yamaha, Suzuki, Kawasaki, Polaris, CanAm, Arctic Cat, Kymco ATVs

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Spiting/sputtering 416
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Posted by: markk

ON my second lap at Loretta Lynns GNCC, My quad started to sound like it was hitting the rev limiter, But it was at only about 5-6000RPMs well by mile marker 9 it was gettin really bad, I couldnt even climb this hill that i tried 4 times. So i had to turn around and go back to the pits.
So yesterday i cleaned up everything on my quad, and ripped the carb off, and cleaned up everything. i pulled my pet-cock off the tank, and cleaned it all out and got every bit of dirt out my gas tank.
So i put it back togeather and rode it, But it still spit at me, So i went to yank that plug out, And noticed that it was 1/2 way out already. So i cleaned it up screwed it in all the way and tried it again. ( i thought that it being 1/2 way out would draw more air than it should, and make it run too lean) But even after the plug was all the way back in, Its still poping on me.
IM gona get a new plug tommarow, and start checking EVERYTHING over and see where the problem is. I was thinking either the plug,coil, or killswitch problem.

If anyone has any ideas post away with them, It kinda has me stuped at the time!
Thanks for any help markk

Posted by: cals400ex

did you take all of the jets out of the carb? i would take them all out and spray it out with carb cleaner when the jets are out. i have seen mainjets and even the 2 screws holding the needle in place fall out which both made the bike run like crap.

Posted by: markk

i pulled the intire thing apart, slide and all and cleaned everything!

Posted by: Rico

Make sure your vent hose isn't clogged or partially clogged. YOu can remove the gas cap and start it up to see how it runs.

Make sure the airboot is connected to the carb real good too, it will make it fall on its face. I've had mine come loose many times.

Posted by: TC426EX

quote:
Originally posted by Rico

Make sure the airboot is connected to the carb real good too, it will make it fall on its face. I've had mine come loose many times.

Yeah, same here... Laz told me that its because I removed my airbox lid, the airbox loses rigidity and pulls off the carb. Check that for sure, if its disconnected, it would cause your bike to run like that...

Posted by: markk

Thanks for the info guys, Actully during the race i did check my vent hose, and I checked the intake boots, Because my buddies did that last winter.

But come to find out what the problem was, I noticed that my exhaust sounded a lot worse than it did before. I pulled it apart and NO-packing, and the round tubing, with holes, (it holds packing) WEll it had brokin inside the exhaust and rattles around enuf to break it off in peices about 1/2 of it was gone already. I thought that my valves where way outa wack, But mabey it was because i had no backpreasure.

I stuck one of my stock head-pipes, and stock silencer,with no baffle in and the beast ran fine. I hope this was the problem,

Also if anyone has and good Aftermarket exhausts for a 400ex, Get ahold of me!!

Thanks for the help guys!

Posted by: prepracing

if you put your stock pipe back on and it ran fine, sounds like your running the wrong jet. Maybe due to a weather change

Posted by: markk

Well, i have been running a DYnojet 170, for 2 years now, and its always done really good for me besides the WISP GNCC. And with my stock silencer what main jet do u-all think would be a good number to run?

I was running a 170 yesterday, and it seemed a touch doggy, So i was thinkin of jumping down to a 160, or mebey even a 154/152 whatever size it is!

Posted by: prepracing

sounds like those numbers you have would be in the ball park, just some trial and error testing will find out for sure