XR200 Won't Idle

squeaky

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#1
Hi Guys, I need some help please. My 86 XR200 Won't idle. It starts up beatifully, it has a new pilot jet, the main jet has been cleaned out, the carb has been cleaned, the idle adjusted up and down...it just won't idle. Once you get it going it runs really well, but as soon as you let off of the throttle it dies. Any help or suggestions would be greatly appreciated.
 
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#2
Two things to check are your float level and your clutch adjustment.

Swiss
 

biglou

#3
Why did you change the pilot jet? Did you change sizes? Did it idle before that change? Too small of a pilot jet will cause poor/no idle. Was there any other maintenance done to the bike or changes made that might have caused this, or did it just stop idling?
 

squeaky

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#4
I changed the pilot jet because Keith told me to. It didn't idle before that change. I don't think I changed sizes, I went into the motorcycle and asked for a pilot jet for an 86 XR200 and they gave it to me. The only maintenance I had done before having this problem was changing the oil and air filter. I took the air filter out to clean and Keith told me that it I oiled it too much, so I am cleaning it and replacing it to see if that is the problem. Other than that, it didn't idle before any other work was done to it. Actually, it didn't even run so at least we've gotten that far.
 

biglou

#5
Hmmm, sounds like it just needs a little tweaking. Clean carb, clean and properly oiled air filter, fresh fuel and it should be able to be tuned in. That might involve a larger pilot jet, but I would have to do some research on your particular bike to come up with any numbers. If it is still acting up by DW, there will be plenty of people to help out with getting it dialed in. :thumb:
 

squeaky

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#6
Ok...I believe Keith said he was going to take apart and clean the carb again, and I am going to finish the air filter and replace that as well. I'll keep you posted.

I hope it's not still acting up by DW, but Keith had told me that if it did by the time I found a tool for the job I'd have 40 people working on it. :thumb:
 

Papakeith

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#7
Alrighty, here’s what I know so far.
The bike in question is a 1986 XR200
Last year I replaced the piston/rings/valves, cam chain , and gears (cam and crank).
The bike has run smoothly since November of 2002.
Since this problem has started, I’ve replaced:
  • plug
  • plug cap
  • pilot jet

The last time I personally rode the bike, before the trouble started, it was easy to start, and even pulled me around OK. :silly:

Last Saturday, Squeaky went on a ride without me, and when she came back she complained that it was very hard to start, but otherwise ran OK. Sunday, she went out for another ride, or I should say tried. The bike would not start.

Here’s where I get back into the picture. I kicked until tired, and barely got a burble outta the old girl. I took a look at the plug cap, and the plug. The cap was cracked, and the plug had seen better days. I suggested changing both of them and trying again in the morning.

The next day, Squeaky obtained the parts, and I installed them. The bike fired up, but was smoking, first black, then whiteish smoke. The smoke did seem to clear out a bit after a while, but, when I let go of the throttle, the bike would immediately die. I took of the ignition cover, and found that the pickup plate was loose, and was probably(definitely) making the timing bounce all over the place. I centered the pickup, and started the bike again. It now starts up famously(if I crack open the throttle), but is still very choppy, and almost like a surging sensation.
At this point I decided to do what I probably should have from the beginning. Clean the carb.
The bowl was coated with a white powdery substance (fairly thick in places. As I was cleaning I found the pilot jet to be completely blocked. When I was finally able to see daylight through the jet, it was all egged out. A replacement jet was in order.

Today I installed the new pilot jet, and fired up the bike. Still I’m getting no idle. The idle screw is in as far as it goes.

The odd thing is, that at a stand still if I bring up the RPMs, the bike will almost sound like it is cutting out intermittently. But, when I rode the bike around the field a couple of times. It felt just fine! It would pull me out of corners as well as it ever had. There was no hesitation, no misfiring, or backfiring. Again, though, as soon as I let my hand off of the throttle, the engine would die.

I had work to do on the farm, so I left it like that. Squeaky came over to me and showed me the air filter. It seemed like she may have been a little over zealous with the filter oil, but nothing that would make me expect the type of symptoms that this bike is displaying.

At this point, I am stumped. I really don’t know what the next step should be in my diagnosis.

The intake boot from the air filter does have a crack in the rubber where it seats on the flange of the carb. But that it is not cracked far enough to be past the flange of the intake. I suppose to be sure, I should replace it and probably will.
Any ideas people?
 

Jon K.

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#8
Keith;

Crank it up and spray some WD-40 on the manifold crack. If it is sucking air; the WD will dramaticaly change the way if runs.

Before you try to re-jet or tweak it in any way; check the intake valve clearance. A tight valve will cause all manner of grief. .002 clearance.

The white chalky stuff is aluminum oxide; probably the carb had a bit of water in it over the winter. Nasty stuff; you must get it all out.

Something that is easy to miss on the XR200 carb are the air passages in the back of the bore. This air passage leads to the idle jet, and if it is clogged, absolutely no fuel will pass through the jet. Look into the rear of the carb; the idle air passage is the one on the lower left. The one in the center is the main air passage; but from the sounds of things that one should be OK.

With the idle jet and fuel screw (in the bottom of the carb) removed; spray some carb cleaner (watch your eyes) into the threaded area that the idle jet just came out of. The spray should come out in the bore of the carb, the fuel adjustment screw hole, and the air passage in the back of the carb.

Sometimes it works better to spray into the fuel screw hole. But basically there are four exits for the fuel in the idle passage. Three out of four will not work.

A wear item on the XR200 is the needle jet (the one that the metering needle works in, not the float needle). They come in a set with a new needle and jet. On an '86 model I think I would change the needle and needle jet regardless.

Please keep us posted! :)
 
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#9
" I took of the ignition cover, and found that the pickup plate was loose, and was probably(definitely) making the timing bounce all over the place. I centered the pickup,"

Did you use a timing light to set the timing after this? Make sure the ignition advance works freely and isnt getting stuck, and check valve clearances as mentioned above. Our XR wouldnt idle when we bought it, it ended up being a combination of timing (replaced worn cam gears/chain) and valve clearance. probably wouldnt hurt to check the starter decompressor to make sure its working correctly also.
 

Papakeith

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#10
OK, here's what we did tonight. Basically we went through and rechecked all that had been done already, and a few others.
I pulled the flywheel weight to confirm that the woodruff key was not shorn. This will ensure accurate timing when I actually get my hands on a timing gun.
I re-re-re cleaned the carb. I wanted to be sure that I hadn't missed any journals, or orafices. While there, I replace the two O-ring seals that are on the intake flange.
I re-checked the exhaust valve clearance, and checked the intake clearance. Exaust was fine, the intake needed a bit of tweaking(was too tight).

We didn't reassemble the bike last night. Probably tomorrow night, time permitting, I'll finish reassembling it, time it, and see what happens.
 

Papakeith

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#11
Alright. The bike seems to be running. Although something is still not right.
The rough running is gone, and most everything seems well, except I still have no idle.
I can get it to idle manually (holding throttle open a bit) at what I consider a good RPM range. but as soon as you completely release the throttle, the engine will shut off. I took a look at the plug, and it is covered with a sooty black powdery stuff. Granted, some or most of the soot should be from earlier in the week when it was puffing blackish smoke and sputtering and popping. I will clean the plug thoroughly tonight, and/or replace as necessary
Keith- No timing light, I just dead timed it. The ignition advance is free and in good shape.
The bike will now start on one or two kicks.
Jon, maybe I am missing the passage you are referring to. But I only saw two brass tubes on the intake side of the carb. Is there another passage that I'm not seeing?
 
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#12
Papa / Squeaky.

Check the intake manifold again. On the older XR's the rubber on the manifold can get hard and seperate from the aluminum flange. If it is a small crack, the bike will start and run at a higher rpm, but at idle, there will not be enough vaccum to operate the pilot system properly.

I would remove the manifold and inspect it very closely for any cracks or holes.

Like Jon K suggested, check the pilot air system. Blow air into the pilot jet orface and make sure air is coming through the rest of the connecting air passages in the rear of the carb and also out of the air screw hole.

Good luck. :thumb:
 

Jon K.

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#13
Originally posted by Papakeith

Jon, maybe I am missing the passage you are referring to. But I only saw two brass tubes on the intake side of the carb. Is there another passage that I'm not seeing?
Yup; that's them. The one on the left is for the idle. The one on the right is for the main. They allow a bit of air to flow through them into the fuel passages. They must be clear.

Spray some carb cleaner into the left brass tube thingie. It should exit out of the slow jet, the mixture screw hole (after the screw is removed), and into the bore of the carb toward the engine side.

You can see that hole in the bore if you look in the floor of the carb bore toward the engine. The mixture screw actually protrudes from this hole (and sticks slightly into the bore) if screwed all the way in. You can also see just a tiny bit of light through it if you sight through the screw threads and through the hole.

Come to think of it; I have seen a few cases in which the tip of the mixture screw has broken off in that hole, plugging it up hopelessly.

That black sparkplug could be causing you all manner of grief; get a fresh one in there quick! If the plug continues to blacken; change the previously mentioned needle and needle-jet to clear that up.

Happy trails! :)
 

Papakeith

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#14
OK, Both of those passages are clear. I agree about the spark plug being an issue. It was new a couple of days ago, but due to the problems it has gotten all carboned up. For the 2.00 I'll just replace it, and get some spares while I'm at it :)

89er- I just want to get my terminology straight. When you say intake manifold, are you reffering to between the carb and the cylinder head? Or the airfilter and the carb? The piece between the carb and the cylinder head is metal, and uses O-rings to seal. The piece between the airfilter and the carb is a rubber "boot" for lack of a better term. I will be replacing that piece because it does have a small crack right where it meets up with the carb. I don't believe that the crack goes past the flange of the carb, but at this point I don't want to leave anything to chance.
 

Jon K.

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#15
Originally posted by Papakeith
The piece between the carb and the cylinder head is metal, and uses O-rings to seal.
Ummm . . . . it is? That's news.

Please look again and assure me that I haven't lost my mind. :)