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04 Rubicon, Decreased power and won't idle right when hot.

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  #21  
Old 10-06-2007, 10:24 AM
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Default 04 Rubicon, Decreased power and won't idle right when hot.

During all of this I did not mention one thing but it has to do with fuel and the carb. Is is normal to always have to choke the machine for it to start even when it is warm?

If I let it sit for more than 2 minutes after killing it I have to choke to get it started and I have noticed that my buddies Rubicon that I am working on (even though it is wore out) starts better than mine an does not require as much choking.

I understand having to choke when the engine is cold or it is cold outside but it can be 100 degrees here in Tx and if it sits for more than 2 minutes I have to choke it.
 
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Old 10-06-2007, 11:29 AM
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Default 04 Rubicon, Decreased power and won't idle right when hot.

No, that's not normal. It should not require choke when starting after it's been run recently.

Is the pilot screw set properly? Bascially it should start at 2 5/8 turn open from lightly seated. Then with a tachometer and the motor idling at 1400, turn the pilot screw in or out until you find where it reaches maximum rpm idle, then turn the pilot screw in slowly until the idle goes down 100 RPM. From there go one turn open. Then reset the idle speed with the throttle stop.
 
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Old 10-06-2007, 11:55 AM
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Default 04 Rubicon, Decreased power and won't idle right when hot.

I do have a tach. for small engines because I have set the idle speed on this machine before. I will check the pilot screw. That's weird because this machine has been like this since day one.
 
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Old 10-06-2007, 08:45 PM
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Default 04 Rubicon, Decreased power and won't idle right when hot.

Okay, it would help if I gave you the correct information. After looking at the machine the spark arrester is still in. I must have been thinking of my Buddy's Rubicon that I work on because he is not mechanically inclined. His old spark arrester must be the one on my work bench.

I took mine out and it appears to be fine ( I cleaned it anyway) then put it back in.

I attempted to set the pilot screw but got some irradiate readings on my tach. jumping all over the place then it would clear up then just as I get started again it would start again. I could never get the machine to idle at 1000 at 1100-1200 it would start missing and die.

I am thinking maybe a cracked coil or a short in the wire.

I am going back out tonight to run it in the dark and see if I can see fire jumping somewhere.

I did go and hook my tach. to my welding machine and see what kind of readings I got and it performed as expected so I believe the problem is not in the tach. My tach. is a Pulse 1000 and has been a good tool for several years now with no problems.

I also pulled the spark plug and this is something I have never seen before, the plug is dark, as expected, on one side and light colored almost clean looking on the other. No deposits or gunky stuff.

If the pilot screw is off it is because that is the way the tech. at the local Honda shop put it. And I did ask when I picked it up if I needed to adjust anything other than the idle and he said no.

What do you think now?
 
  #25  
Old 10-07-2007, 01:52 AM
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Default 04 Rubicon, Decreased power and won't idle right when hot.

I never use my choke, even with temps down to freezing it still will fire without choke.
SInce you are haveing fuel issues all across the board, idle and under load im thinking maybe a vaccume leak? if no leaks Check the rubber diaphram above the carb slide- i dont know alot about these CV carbs as im a X 2 stroker mechanic but i do know that these carburaters really hate sitting in storeage and will gum up way fast with todays fuels in storeage, has your quad ever sat over 3 months? If so its either a plugged pilot, air screw, passageway or a torn rubber blatter above the vaccum slide. I am leaning towards the rubber carb bladder above the slide as that will effect the entire powerband
 
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Old 10-07-2007, 01:54 AM
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Default 04 Rubicon, Decreased power and won't idle right when hot.

Issues like this are why I want honda to build a Rubicon II 600 with power stearing and EFI as with EFI you plug your laptop into the OBDII port and then replace the failed part that the computer says needs repalced. Back on the trail in no time [img]i/expressions/face-icon-small-wink.gif[/img]
 
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Old 10-07-2007, 10:26 AM
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Default 04 Rubicon, Decreased power and won't idle right when hot.

The machine sat at the dealer for about a year before I purchased it but the carb has been off and cleaned several times since then (no parts replaced just cleaned)
I am about ready to just replace the carb and power pak so that I can get back to work.
Are there any aftermarket carbs and power paks that are better than stock? I have always heard that Honda stock products are hard to beat.
 
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Old 10-07-2007, 12:51 PM
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Default 04 Rubicon, Decreased power and won't idle right when hot.

a video speaks a thousand words, take a camera phone video of how its misfires when warm and send it to me in a e-Mail mms message. pm me for my e-mail, but If you do end up replaceing the carb id get the larger 2006 carb for a tiny bit more power
 
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Old 10-08-2007, 01:05 AM
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Default 04 Rubicon, Decreased power and won't idle right when hot.

I wouldn't think the pilot screw would cause the the thing to idle for a while, then die. If the mixture were off, you would expect it to run consistantly bad.

I think I'd go over the list of things I posted earlier. I still wonder about a vacuum leak (Spray some oil on the isolator boot while running), and have the valves been checked? The vacuum piston on the carb either sticking or leaking is still a possiblity.

Did you ever check to see how fuel flows from the fuel line when unhooked from the carb, and how it flows from the carb drain?

I presume the tech who worked on your carb didn't disturb the pilot screw, and hence felt that it shouldn't need to be adjusted.
 
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Old 10-08-2007, 01:28 PM
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Default 04 Rubicon, Decreased power and won't idle right when hot.

I adjusted the pilot screw and it will crank now without choking. I used it Sunday but have not put it under a heavy load and have not run it enough at one time to really get it hot. It does sound better at an idle.
I am still concerned about the irradick readings I got on my tach. and the possibility of a short in the wire or the coil.
I tightened the clamp around the isolator boot but it did not appear to be loose. I pulled the clamp up as far as it will go.
I did check the fuel flow and it runs out plenty good.
 


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