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Discussion Starter #1
My 92 I recently bought has been having idling issues. I bought it and it wouldn't even run unless it was fully choked. I pulled apart the carb and rebuilt it. Night and day difference. I replaced the boots between the carb and the engine and the air box. I also cleaned the fuel tank and added an inline filter. Today I changed the oil, filter, and spark plug. I noticed a difference but it will still only idle for about 5-10 minutes max and then dies. It seems to struggle most of that time too. I also should note I adjusted the mixture screw to the factory 2 1/2 turns out. I live in Utah around 4500 ft above sea level. Could being slightly out of mixture be the problem of this? It seems more like it's struggling for fuel than air but you would think at my elevation it would be the other way around?
 

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More than likely your pilot jet is plugged again. One of the most common things people do is clean or rebuild their carb but don't clean or flush the fuel tank which is the source of the problems. Take your tank off and flush / wash it. I use a hose with a sprayer and flush it a bunch of times. Then take fresh gas and pour a half gallon in and swish it around. Empty the gas and let it dry out. Then change the fuel line and add a fuel filter. Clean the pilot jet again and you can at least eliminate the fuel system from the cause of the bad idle.


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Waymore, I to live in Ut, same elevation, Both mine 89, and 91 run and idle perfect, just like Deepseadan said its most likely the Pilot Jet or the Pilot Circuit.
When you clean that Jet you got to make sure you can not see anything when looking thru it. Both mine I could see thru them but there was a like spider web in the middle of them, I must of cleaned them 4 or 5 times before I finally pushed a small wire thru them and they ran perfect after that. I think its the Ethanol that make the web looking thing. It looked to me like it was meant to be there too.
 

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Discussion Starter #4
I just don't see how they could be the problem? I cleaned and sprayed the tank out while I was rebuilding the carb, replaced the pilot screw and jet, and the main jet and nozzle. And then I put in a new hose with an inline filter in it. I then put a brand new tank of ethanol fuel in the tank. That's why I do t see how it could possibly have gotten dirty. That's why I changed the spark plug. Maybe I need a new carb?
 

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The other thing that causes bad idle is an air leak in the intake boot. I know you put new boots on could it still be leaking there? Or maybe check your float level. Did you over oil the air cleaner? Or is it dirty?
 

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On my 91 I got a blockage in the Pilot passage Im pretty sure, I was just where your at with the same issues, I gave up on my self and took the whole bike to 2 different so called experts, both of them thought they had fixed it, no way! they just did not no how a Tw 200 purrs when its running right. I wasted a lot of money and time, I ended up buying a new Yamaha Carb.
Now I don't even have Ethanol Gas in the same Barn as the Tw's.
 

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Waymore its a good thing I don't live as close as you do to Rocky Mountain Atv, I would be in the poor house. :icon_thumbright:
 

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Did you remove the petcock assembly and clean or replace the in-tank screens? Also: "It only idles for 5 to 10 minutes"? Why do you need to have it sit and idle for so long? I either ride my TW or shut it off.
 

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Discussion Starter #10
I did not remove the petcock. And I don't need it to sit and idle for long periods of time. But I think it should be able to of need be.
 

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I agree with Tweaker about the air leaks, double check that the boots are seated and sealed correctly. I have a '94 and the PO put in a 108 main jet #288-14343-54 and ride this anywhere from 3000' to 9000' without a hiccup. Even though you did a thorough job of cleaning everything you might run a small wire through anything and everything with a hole in it just to be safe. If you have the carb off or can rotate it, I'd also recommend shimming the needle with a couple of washers. Your bike won't run so lean and will require very little to no choke once you do this.

Good luck!
 

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Discussion Starter #12
Thanks for all the replies! I checked for air leaks today and couldn't find any... I replaced the old air filter and still nothing. So I tried adjusting the screw and made it worse. Tomorrow I'm going to pull the carb apart again and make sure there's nothing I may have knocked loose and plugged up. I'm also going to adjust the valve clearance and cam chain if I have time. Hopefully between everything I'm doing I'll get some more positive results. So much for the engine and carb being rebuilt shortly before I bought the bike... lol
 

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Discussion Starter #13
So today I re-rebuilt and cleaned the carb, adjusted the valves, and cam chain. Fires right up and idled perfectly. So I took it for a little ride. After warming up once I quit riding it does instantly. Before I can even stop. This is getting really old...
 

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Waymore I keep wishing for good news from you. Maybe you will have to bite the bullet and put a brand new carb on it. If you do you better stay 1000 feet from Ethanol from then on.
 

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Waymore I'm still suspecting the pilot circuit / jet is clogged again. You probably had it nice and clean but debris got in there again.

I know, I went through about 10 carb cleanings and clogged pilots, two tank flushes, petcock cleanings, fuel filter that did nothing, on my daughters raptor 80 quad before I finally won.

You said the bike started and idled perfectly so that indicates to me it was probably clean for a bit. The pilot jet hole is so small almost anything soft or hard could partially block it causing major idle / running issues.

Also if you're running a fuel system cleaner like seafoam or stabil 360 that may be causing unseen debris to break free and clog the pilot.


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Is this a CA bike? Do you have the charcoal canister on it with hoses? When you put the new intake boot on did it have a vacuum nipple on it? is it plugged?

Now this is more no idle when hot. Would a cracked head do this? Bad valve? Thinking out loud here.
 

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I used Kreem tank liner in mine. Just a recommendation. Some say the coatings come off but in Texas mine has been on with no issues for about 15 years now. I have it on 2 bikes. This makes the entire tank coated so the only exposed metal is inside the filler neck. I just rebuilt my carb for the first time this year with over 40,000 miles.
 

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Discussion Starter #19
My tank does have a lining like that. And no it is not a cali model. So what did you end up doing deepseadan? Just clean and clean until it finally worked? I'd almost rather buy a new one and save myself the hassle and possibility of it not working. Would it be worth taking it to a professional to have it done? Or just be money ahead to buy a new one?
 

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My tank does have a lining like that. And no it is not a cali model. So what did you end up doing deepseadan? Just clean and clean until it finally worked? I'd almost rather buy a new one and save myself the hassle and possibility of it not working. Would it be worth taking it to a professional to have it done? Or just be money ahead to buy a new one?
When you pulled your float bowl off this time was it polished clean?

I was super fed up and hated dealing it. Knowing what I know now I'd throughly clean the tank before doing anything else. Maybe try filling it with white vinegar and soaking it or high pressure water with a nozzle and shake it hard. Do that a bunch of times. Check every part in the tank to make sure it's clean, especially the petcock. Then flush with some fresh gas and let it air dry. Then check your fuel source to be sure it's clean.




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