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Discussion Starter #1
Hello,

My primary machine, a 2000 400ex with a new 416 kit, always had a stuck idle adjust screw. It was ok for most riding, but a little low at some altitudes. The flex potion of the screw was rotten so I just replaced it all with a new OEM kit. I noticed when removing the old screw, it was screwed in tight against the spring. I put in the new screw, adjusted it roughly where the old screw was as a starting point and reassembled.

I fired up the machine, wouldn't idle of course, and let it warm up using the throttle to hold RPMs. I slowly adjusted the idle screw in, and nearly to the point it needed to be to hold idle, it compressed the spring to the max and stopped. Just like the previous spring.

While not ideal, I temporarily adjusted the throttle cable to tighten it up enough to hold idle, just in the back yard atm. I plan to pull the carb off and examine the throttle portion of the carb and see if there is anything else I can adjust.

My question is: I could get some snips and cut off a couple coils off the spring, that would let me get another turn or two on the screw and probably get me to proper idle... but is there anything else internally that can be adjusted? Its like the butterfly isn't indexed properly to the throttle cam assembly. Its really close to where I need it, but its still at the end of the throttle screw adjustment range.

Just thinking about a plan of attack before I yank it off and work on it again. Thanks in advance

-DallanC
 

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There were no clear pictures in the service manual, but I worked on one one time with a similar problem - there is supposed to be a steel rivet in the operator that the idle screw pushes against. The rivet was missing and the idle screw was setting in the hole. I made a rivet from a nail and pressed it into the operator and it worked like new with plenty of adjustment.
4382
 

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Discussion Starter #3
Genius!

Yes I remember the area the screw was setting in, I thought it was a dimple rather than a hole (but I didn't look close enough apparently). That is where the "Rivet" must have been. Ok that's good to know, was thinking maybe a cap or something sat on the end of the screw, I didn't consider something missing from the "drum".

I can fabricate something to fit in the hole for the idle screw to rest against. A Nail seems a simple place to start and maybe some jbweld to keep it in place.

Thank you, I figured this would be an issue someone has run into and had an answer for. Planning to hit the dunes this weekend so I'll yank the carb tonight and get started on a fix.

-DallanC
 

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Discussion Starter #4
For the sake of clarity and anyone in the future that runs into this issue, here's a picture of the part that seems to be missing from my carb. I found this image in the Partzilla youtube carb rebuild video. Give me an idea of what the OEM part sortof looks like

4383


I might try tapping this, and adding a screw with locktite.

-DallanC
 

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I might try tapping this, and adding a screw with locktite.

-DallanC
The only time I had to fix one, my first thought was what looked like the original - but my next fix (if I ever run into it again) would be to tap and install a small screw. The perfect screw for this would be the spanner drive screw. It's head is almost perfectly flat.
4384

It could be Loctite'd, but I think I would 'dimple' the lead end of the screw shank and smash it with vice grips to permanently prevent the screw from loosening.

The rive mad from a nail worked too, but nails are soft and the screw shown is stainless steel, but the nail head worked perfectly.
 

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Discussion Starter #6
So I removed the carb last night and found the rivet was still there... but the screw needed another 1/8-3/16" to get it to touch the cam. IDK why this would be. All the linkage was firmly attached, didnt seem bent etc.

I went back to my first idea, I took the original spring and snipped it in half. That gave me enough adjustment range to get it to idle. I have the other spring from the new kit if I ever need it.

-DallanC
 
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