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idle won't stay consistent

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My bike has been acting wierd lately :cry: If i let it idle for a few seconds it will rev up 500rpm like it's lean. I've adjusted the fuel screw but it doesn't help at all on the problem. I checked the throttle cables and hot start nither are binding. My valves are all in spec and i couldn't find an airleak. :cry: I pulled the carb apart and cleaned it out also. And yes the air filter is clean :cry: I can't find the culprit at all and have run out of ideas.

I'm hoping it was a common problem for a 2002 crf and i just couldn't find it in my search. :cry:

My jetting is a 42pj-172mj-4th from the top on the needle.

Thanks

Bill :cry:

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I'm no expert, but the first thing I would suspect is an airleak or the hotstart maybe sticking. Being that it just started doing this with no mods, narrows it down a bit.

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For sure... You did everything I would suggest doing. It sounds like a lean condition. I would suspect an air leak. The top cover of the carb is known to get loose. I'd also check the sealing rings where the airboot joins with the airbox. Of course the clamps on the carb. Clean the carb again?

What about something simple like throttle cable operation or fuel screw?

Does it pop on deceleration?

If that doesn't fix it I'm stumped. :cry:

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Do a search on (hanging idle). It seems that these newer crf's with the FCR carb idle real weak. I've read a few post where people had to richen the pilot jet up some , also where some lowered it to solve. My problem with the hanging idle was the carb slide plate had a bad seal. I had to spend $60 to get a new throttle plate that came with the seal I needed. My final jetting was a 45pilot 4th clip position and 165 main. ported head sea level trx valves heavy duty springs

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It sounds like the classic floating valve coming loose. I used gasket sealer to get it to stay put on my carb slide as the oring doesnt hold the two together over time.

This was a very tricky problem to fix when I encoutered similar issues as described.

good luck

Tin

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I've never heard of this, could you expand on it a bit more please?

Thanks,

Pat

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The floating valve is the removeable piece of the slide, take a look at the fish on service honda. It can be removed when the slide is taken out of the carb. It can also be installed up side down causing weird idle conditions as well.

I found on my 03 and a few months ago on my 04 that the oring stops holding the "valve" in place. When this happens it rattles around between the slide and carb body (engine side), which causes completely irratic idling. I tried all kinds of jetting changes and idle screw settings, but it was never consistent for long. I noticed on rough trail is when it would really change and that finally gave me the clue to check it. Sure enough after a nasty single track ride I pulled the top off the carb and the "float vavle" was leaning against the carb body! This allows air from the top of the carb to bypass the slide, causing a lean condition and very very wierd idling as it sometimes would seal then bounce loose again....

I took out the slide and used a bit of threebond gasket sealer to keep it attached. You cant order the oring seperate so this seemed like the best way to fix it. The threebond has held without issue all summer and no more probs.

If you use contact cleaner in the carb or pump gas I believe it makes the oring swell therefore allowing the valve to come loose from the slide.

This applies to all FCR carbs, at the local shop another guy on a Yamaha was experiencing the exact same thing....

This problem about caused me to get rid of the crf, but I finally got to the bottom of it and am happy with the bike again.

Tin

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It sounds like the classic floating valve coming loose. I used gasket sealer to get it to stay put on my carb slide as the oring doesnt hold the two together over time.

This was a very tricky problem to fix when I encoutered similar issues as described.

good luck

Tin

Just an update..

This seems to have been my problem. I sealed it with some gasket sealer and the bike will run and idle consistent again :cry: I'll be taking it out for a test ride tomorrow and will order a new slide on Monday.

Thanks for the help :cry:

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The floating valve is the removeable piece of the slide, take a look at the fish on service honda. It can be removed when the slide is taken out of the carb. It can also be installed up side down causing weird idle conditions as well.

Tin

I installed mine upside down and got the thing to run but it had a hanging idle on decel on the track and would only idle at high rpm's. Turning the idle adjuster down would slow it down graudually then just like a lightswitch go dead.

The hole in the slide plate needs to be at the bottom.

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Tinman.....Do I understand you correctly?......You bonded the floating valve to the throttle valve? Will you be able to get it apart if you take it out again? Does it actually float now that it's bonded?.....or did you just seal the oring to the floating valve?

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Boy am I glad I found this thread. I was strongly considering selling my '02, because of the now known "hanging idle". I could not find the problem! It made tight trails a muderous proposition.

Thanks!

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I have been meaning to post this same question for quite some time, my 02 has been doing the same thing, and in tight woods it is a killer. I just purchased a Recluse auto clutch, I was concered if the inconsistant idle would cause any problems.

Tinman_327 you seam to know what you are talking about, I looked at the service honda site and printed off the carburator parts list. Could you let me know which parts I would need to order to fix the problem. I would like to have the parts before I take the Carb. appart.

Thank you in advance :cry:

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I called my local dealer here in Vancouver to order the part, they wanted $160.00 + 14% tax, comes to $182.40 Canadian funds I called Service Honda they want $57+$20 freight USD at 1.22 exchange comes to $94.00 Canadian funds, delivered to my door.

Whats up with that :cry:

For that kind of money I sure hope it fixes the problem!

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Didnt see the thread pop up till now...

The status of my "floating valve" is that it is still bonded to the slide. I used Three bond grey I think 1011. It resists fuel and seems to hold fine. It has been probably 50 hrs since I did that without problem. Personally I wouldnt bother with replacing the floating valve seal, and floating valve.

I also think I cuased the problem by using brake cleaner on the carb.... it makes gaskets expand big time! I think carb cleaner is much more approptiate.

The auto clutch will be a disaster with the floating vavle problem! I know personally...

Tin

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