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XR600R weird idle

27 posts in this topic

Alright, see if you can follow me. I did a few things to my 1997 XR600R and now it's running like crap. I cut the side panel at the airbox and replaced the stock filter with a twin-air. The bike also has a Yoshi pipe and 65 slow and 165 main jets (which were in it before the airbox mods). When I start up the bike with a new plug it idles fine until I give it some throttle. Then it idles high for a few seconds before coming down, but if I twist the throttle the opposite way when it's idling high it moves the carb and the idle returns to normal. However, sometimes when I twist the throttle hard it just bogs. i took the plug out to check it and it looked dry, but not too white. So, whats going on? Forgot to mention that when I pulled the pilot screw out their was no o-rings on it. Is that normal?

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The pilot jet sounds lean. As far as the pilot screw,I would bet the o ring is stuck up in the carb body.

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This a dumb question, but is the pilot jet the same as the slow jet?

No such thing as a dumb question.........yes the pilot is AKA the slow jet. Sounds like the pilot is lean. Peek through the pilot jet and see if maybe there is some debris in there, the orifice is very small and clogs easily. If that is not it, go up a size or two on the pilot and see if that helps.

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Sorry, I still call a slow jet a pilot jet. How far is your pilot screw out? any more than about 2 1/2 turns out you need a bigger pilot. Tape the holes in you side cover and see if it gets better. If so you know you're lean.

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Alright, so I'll take the carb apart tomorrow to clean and change the slow jet. If I do change the slow jet doesn't the main jet need to be change as well? And does the needle need to be moved?

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I finally got the jets in today and replaced them. There was a 65 slow and 165 main. I replaced it with a 68 slow and a 168 main. This helped a little, but didn't totally solve the problem. When I twist the throttle really hard and fast it bogs. Also, when I adjust the fuel screw in all the way it doesn't stall the bike and when I turn it out the idle doesn't increase. I can almost screw it out entirely. So, what's going on? :ride:

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Probably you have a dirty carb, try a good cleaning. Could also be an intake air leak. Check the carb adapter and make sure you are getting a good seal where the carb fits into the rubber boot. This is a long shot, but I have seen instances where the rubber O-ring between the head and the carb adapter was leaking, might be worth a look.

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I cleaned the carb before I put the new jets in, but it didn't do much. I'll check the o-ring tomorrow. Would moving the needle position help at all?

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The o-ring is fine, I cleaned the carb again and then moved the clip down on the needle to richen it. This made almost no difference. I put the 65 slow jet back in to see if this would help and it did a little. It still bogs after I get on it hard. For instance, when I'm in first gear and I'm just idling along and I give gas to go it just dies. Also when I was in second gear just about top out, the bike shut off. So just to recap, I now have a 168 main, a 65 slow and the clip is in the 2nd position from the bottom. One quick question about crankcase breathers, is the top hose supposed to connect to anything? I feel it pumping out a lot of air so I was just curious.

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One quick question about crankcase breathers, is the top hose supposed to connect to anything? I feel it pumping out a lot of air so I was just curious.

Yes, quite a bit of air goes in and out. When the piston goes up it sucks in 600c of air. When it goes down, that 600 cc goes out. Add any piston low by to the out. When the rings wear out, blow by increases. When blow by gets too much, oil starts blowing out. No oil usually means it OK.

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No, there's no oil blowing out yet. I just wasn't sure if that top hose connected to the airbox or anything. I think I'm going to go up on the main jet to try and correct the stalling and bogging problem. Will that help?

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I should also mention that I'm at sea level. If that makes any difference.

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Not to change subject but check to see if stock choke plate is still there & if so change it ASAP ! Did I say ASAP . YES ASAP ! Because you could put choke in 1/2 way position to see if the richening helps the bog & thus pointing in the direction of solution for richness or leaness.But I did not want you to do this with stock plate, as it might suck in a piece of it as it has with many others here . then you will have much bigger problem & skinnier wallet!

Good luck ! BB

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Yeah, I'm going to order that plate from XR's only as soon as I can along with that oil temp dipstick. I did try the choke when I was riding and it did help a bit. I put it to 1/2 choke and it seemed to run better. I know it's a lean situation, but would I increase the pilot or the main?

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Pilot is basically only idle & a tad above , Main does the rest. I'd say you have an air leak or still have a dirty carb inside.(clogged passage) But I could be wrong. I got an Edelbroke now. Also , cant remember , but is there a place on carb with 3 screws & little cover plate? diaphram ? Not sure if there is one & what it does.

Also do you know how to check float level? a low amount of fuel in bowl could also cause this condition. & make sure you have good flow from petcock while your at it.(petcock wont give your symptoms but good to know for later high speed stuff.)

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Also , cant remember , but is there a place on carb with 3 screws & little cover plate? diaphram ?

Yep, it's only got two screws, but yeah it's a diaphram. As far as the float, I know how to check it, but I don't think that's the problem. As far as the petcock, it flows pretty good so I don't think that's the culprit. I think I'm getting the hang of jetting (finally). I found a pretty helpful guide over at 4strokes.com where it said to place tape on both the throttle and throttle housing then mark off both pieces of tape at idle, at half, and at full. Then test the spark plug by riding at WOT and shutting the bike off. Then half and then at idle. Well, I pulled the plug on the first run and the core was white. So, I'm going to up the main, but first I have to order them and I don't know where to get a kit.

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I checked the float today and it was at factory settings, so I don't think this would cause it.

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You said the idle screw in and out did not change anything. Did this get resolved?

I am running a 155 main 68 pilot in a 94 xr 600 runs great except for a intermitent

stall at idle. Has a white bros pipe and a twin air with some holes in the air box.

I have the same issue with the idle screw not making any real difference.

The tip goes in the hole and never seals off even turned all the way in.

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My 94 idle jet ran best at 1/4 turn out. I cleaned out carb & still same. Even tried my bud's needle.( same result) I got the bike used , so who knows what was done in its prior life.

BTW, the needle controls gas flow not air.

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