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How to Set Up the Carburetor - Need help ASAP

104727 Views 19 Replies 6 Participants Last post by  bassfisher704
I was on mental cruise control when I pulled the screw with the spring under it (is that the jet?) inside the carburetor and I started counting turns to unscrew it instead of counting turns to screw it in. Now I don't know how to get it back in at the right adjustment.

This is the one that is inside of the carburetor, so I really want to make sure to get it done correctly the first time (since if it is not right I will have to disassemble the carb to adjust it.) If there is anyone with a service manual that could let me know or could post a couple of pages dealing with the carburetor adjustment, that would be great.
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I can help and will be here for a while but on the inside of the bowl there is no screw with a spring. The air/mixture screw will be on the front/bottom side of the carb on the outside of the bowl. Depending on the model 2-2 1/2 turns out from lightly seated will get you very close on that one.
I can help and will be here for a while but on the inside of the bowl there is no screw with a spring. The air/mixture screw will be on the front/bottom side of the carb on the outside of the bowl. Depending on the model 2-2 1/2 turns out from lightly seated will get you very close on that one.

OMG! You are right! I can't believe how stupid I was. It was on the bottom of the carb in a row with the other screw-type thingies inside the bowl and I just assumed that this one would be covered by the bowl as well, but now that you mention it, there is an indentation on the bowl so that it does not cover this one. I am half-tempted to delete this post to hide my own stupidity from the world, but maybe we can redeem ourselves with some good tech on carb tuning:

If I start it at 2-1/2 turns out, what symptoms will I see once I start the ATV if the screw is too far out (too rich) or what symptoms will I see if the screw is too far in (too lean?) If I can figure that out, then I should be able to get it back to tune up again.
Oh' your not alone, I always just view the new post and just looked up and seen I'm in the Recon section. On the Recon initial setting is 1 1/2 turns out. It's mostly to get the idle mixture set right and you have it right on the mixture in is leaner and out is richer.
Right, I just don't know enough about engines to know when it is running lean versus when it is running rich. What are the symptoms of each condition?
On the lean side (screw in) it will take a while to rev down and will idle fast and erratic. On the rich side it's going to idle rough and will probably kill itself after few min. Pretty much if you get the bike to idle good then it's set right. Usually you can just set them to the initial setting and it will be good but different locations might need a 1/4 turn to get it just right.
What kind of contortionist masochist does it take to adjust that little screw? I certainly can't get a screwdriver on it and the only way I could get it to turn was by sticking the blade of a little fuse up in there (while burning my hand on the cooling fins of the engine) to try to turn it that way. Sheesh, they put it in a spot that is little better than inside the fuel bowl - how do the factory techs get at that thing? Do they have a special tool?

Anyways, I was just out there fiddling with it and I did notice it took a while to rev down (too lean according to your instructions,) but it was also idling along fine and then would just miss and die. I know it is getting good fuel since I now have some clear fuel line and a clear fuel filter on it.
I started wondering about spark, so I was going to stick my inline spark checker in between the plug and the wire. Great idea, but it seems like just about any part I touch on this ol' abused machine falls apart in my hands. Sure enough, I gently pulled the plug wire off the plug and it literally came off in my hand - yes, the plug cap came off the plug wire. What's worse? Imagine my dismay to learn that it isn't just a spark plug wire that I can replace with some spares I have laying around the shop and that I am now going to have to order a complete plug-wire and coil from Ebay. It looks like it will be a few days before I get this POS rolling afterall. :storm

The worst part is that I still don't know what was actually the problem. I guess since the plug wire came apart, there is a good chance that there may have been an intermittent short in that system - maybe.
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If it was just the cap that fell off then just screw it back onto the plug wire. There is a special screwdriver to adjust the screw, it's cable driven with a 90* at the end. How many turns is the screw set at now? I just posted some basics but it can go both ways sometimes.
Awesome - I didn't see that it could be screwed back in - just assumed it was broken. Makes sense on that special screw driver. I started it out at 1-1/2 turns and dialed it out about 1/4 to 1/2 turn but couldn't really mess with it a lot due to the fact that it was near impossible to turn that screw and the engine was intermittently dying with (seemingly) no rhyme nor reason.

The spark plug cap is not "seating" solidly on the plug and could very well be the source of my problems. This is what the plug looks like - is it supposed to have that little screw on plug thing on the plug end of it or is this correct? The threads on the plug (the little ones that go to the plug-wire, not the big ones that go into the block) are all stripped. I am not sure (obviously) how this is supposed to look in stock OEM configuration, so I can't tell if I am missing something, but I can tell that something is not right - the plug wire is held onto the plug only by the rubber boot and the metal to metal contact is totally loose.

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OK, I see now that inside the spark plug cap, there is a little spring that is supposed to hold the cap on the plug.

On mine, that spring is shot, so it wasn't making good contact. I wrapped the wire from a twist-tie around the end of the plug to make better contact and that seems to have done the trick, but it is still totally erratic and I think I have a fuel delivery problem.

I can see the fuel through the new see-through lines and filter I installed and there are all sorts of bubbles when I dump the carb bowl (using the petcock on the bottom) it doesn't refill except very very slowly. I am not sure what the problem is because the petcock on the bottom of the tank seemed to flow fine.

Maybe the needle in the carb is not letting gas in? Before I installed the carb I made sure that the float and the needle were working well together and that there were no restrictions.

Until I know for sure that the fuel is flowing well, I can't get to tuning the carburetor. This is driving me nuts. I guess my next step will be to unhook the fuel line from the carburetor and run it into a bucket to see if it is flowing well.
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OK, so I now have it to the point where it will run. The fuel lines all checked out and I bled some air out of them to make sure they were not a problem. I also hooked a tube up to the carb and blew into it to make sure that there was a good passage-way for the gas - there is. So it is running now, but not really good. Here is what it does:

It idles just about right, but once every 10 seconds or so, it misses and you can hear the slack come out of one of the rods in the engine (a little "tink" sound)
If you hit the throttle hard, it revs up good, but backfires just a hair on the way back down (not a full backfire) but usually, it won't come back down to idle speed - it comes down to 2 or 3 times as high as idle speed. In order to get it down to idle speed, I have to just give the throttle a little "blip" and then it comes down to idle speed where it continues to run, but misses occasionally.

One thing of note here - the o-ring on the air/fuel mixture screw is actually broken. I did just throw it back in there with the break in it and I figured it would work fine that way, but maybe I was wrong? Any other thoughts?
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Did you end up soaking this carb in a carb cleaner (I always called it to cook/boil out the carb) or was it just sprayed out with carb cleaner in an aerosol can? There might just be enough varnish left in the passages of the carb to be messing with you.
I did soak it in B12 from a 1 gallon can for about an hour and then I blew out all the passages with compressed air. I looked through all the pieces I could to make sure I could see light coming through the other side. I thought I had it pretty well cleaned out.
I've been having almost exactly the same problem. After thorough carb cleaning I have gotten to the point where it idles on it's own and drives fine but has the slight miss and some valve noise as you described at idle, revs up nice but pops a lot on the way down again as you described.

A few things I have been thinking may be causing it are incorrect float levels, need of a valve adjustment or air/fuel screw not set right.

I don't know if this is right, but a friend of mine told me that the best way to adjust the air/fuel screw is to set the idle speed screw to your desired idle RPM, then adjust the air/fuel screw till the idle raises and you get it to the fastest idle possible. When the idle is at the fastest RPM, bring down your idle speed screw back to your desired idle and the air/fuel screw is then adjusted right. Don't know if this is true or not but im going to give it a try. I'm also going to check all the grounds on my bike, clean em off, clean the contacts on the coil ect... as there is a lot of dirt and corrosion. I ordered a remanned carb for 50 bucks, so after all this is done and the new carb is on...if i still have the problem im moving to the valves. Figured i'd share as it seems like our bikes may have the same issue.
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Just a little update on the problems I was having:

  1. I now have the carb adjusted at 1.5 turns out and it runs fairly OK
  2. I had to shave down the brass throttle ramp thingy that rests on the idle speed screw. I think the erratic fast, then slow idle problems were caused by the fact that the idle screw had worn a groove into the brass throttle ramp thingy so that it wasn't always coming to rest in the same spot on the idle screw. I used a file to smooth it out again and it seems to have helped.

It now idles OK sometimes and sometimes not and it still backfire-gurgles on the way down. I am at about the same point where I think it has to be either air/fuel mixture or valve adjustment or both. Is there someone who can post the valve adjustment procedure and specs from an FSM?

On a separate note, mine is also having this problem where it seems to build up pressure in the carburetor when it gets really hot. I'll be riding around for 1/2 hour then it will suddenly just not have any fuel. It seems like the air pressure in the fuel line stops the gas from coming down the gas line into the carb bowl (and I can see bubbles coming up out of the carb up the gas line. If I open the line and let the pressure out, then it will go again. It is a really weird symptom that I may be misdiagnosing. Maybe I am just still getting limited flow through the in-tank gas filter, but how can I replace that? Do I have to buy a completely new fuel/reserve valve?
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Hey jode can you take the petcock off the tank? If so just spray it and blow it out with air and if I remember correctly there is a screen in that petcock that can get plugged up. I have had to poke a wire into them before and break the screen to get proper gas flow but if you do that make sure you put a filter inline to take its place.

As for valve adjustment, I never did a Recon but it shouldn't be much different than any other Honda, biggest thing is getting to the valve cover and removing the threaded caps for the valve adjustment holes. For a couple of years, they didn't put the threaded caps on and you had to remove the valve cover which is no big deal (4 bolts). I don't know what setup is in the Recon.

You can look at the valve adjustment procedure in the Foreman section just to get an idea of what's all involved. Most Hondas are .006 +-.001 so I usually set them at .005 ON A COLD ENGINE. And also you must have the piston at the top dead center on the ignition stroke. Some guys use a screwdriver in the spark plug hole and turn the motor over to find it or there should be a plug on the side of the motor you can take out and turn the motor over until you can see a "T" on the flywheel.

Hope this info helps you get it back on the trail. Good luck.
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Sorry jode it was in the how-to section here
We have 2005 TRX350TE Rancher, rebuilt carb, put all back together, started it up set the idle. got on to ride it, get going it seems to be fine till I try to go full throttle. it just doesn't get up to speed, pull choke out seems to run like it should. I know this isn't right, need some help on this
We have 2005 TRX350TE Rancher, rebuilt carb, put all back together, started it up set the idle. got on to ride it, get going it seems to be fine till I try to go full throttle. it just doesn't get up to speed, pull choke out seems to run like it should. I know this isn't right, need some help on this

Sounds like there's still dirt in the main jet or main jet circuit.
sounds like I need to clean again and see how it acts.
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