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'87 XL600 running ruff

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Hey all. Been a while. So, the '87 started running rough a couple months ago: popping upon deceleration, getting harder to start, etc. I never had to choke it before to start it, but now that is the norm. When running, verrrry light throttle will get the motor to spin up. If I gas it, the motor cuts out and will die if I don't back off on the throttle. When I can get it to spin up to high rpms, I check for black exhaust: none. I tried riding it to work a couple weeks ago and the damn thing died on the freeway. Like it ran out of gas, but it wasn't. And yes, the gas was on. Even tried flipping to reserve as I'm coasting on the freeway. No worky.

 

Previous experience suggested the air cutoff valve. So I pulled the carbs out, because I hadn't cussed and threw tools in a while. Pulled the ACV out and it looked new, with no pin holes. I reassembled the set and toss 'em back into the bike. No, I didn't pull the carbs apart and go through 'em, as it had been done professionally right before I got the bike, and it has only had about 1k miles on it since. Put it all back together (including tearing off all the California Emission crap) and tried it again. Absolutely no difference whatsoever. Someone suggested the airscrew was out of whack. So I played with the airscrew adjustment (See above mention of the emission control crap, only way you can get to the airscrew with the carbs on the bike). Again, no difference. And oddly enough, I moved the airscrew from buried; 1 turn out, two turns out, three turns out, and yes, ALL the way out, it it made virtually no difference. It ran only slightly worse with the airscrew removed. Blew out the airscrew channel just for the heck of it. Nada.

 

I also put fresh gas in and cleaned the air cleaner prior to all this other hocus pocus I tried. Anyone have any ideas? I'm thinking maybe main jet cloggage. The weather's finally getting ride-worthy here in the Pacific NW and I'm getting an itchy throttle wrist...

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I'm thinking maybe main jet cloggage.

I'm thinking you're right. The duals are a PITA to work on but it's probably got the idle circuit and pilot jet plugged up. When you pull them out replace all the bowl screws with allens. At least then you can pull the bowls off and blow things out with the carbs still on the bike. Edited by valvesrule

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 consistent spark? plug cap on tight? fuel filter? theres also a screen above the petcock inside the tank. you can get at it by removing the petcock from the tank. relief line on cap clear? no problems there, head to the carb.

bark.

Edited by garthr

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Both main jets need to come as does both the tubes they screw into..Pilot jet needs to come out,,It's in a hole in the left hand carb.,,thinnish slot head screwdriver is needed for it. When you have them all out look at the sides of both the pilot and the tubes the main jets screw into.Running up the side and on both sides of all items are tiny holes. Get a strand from a wire brush and run it through all the tiny side holes and obviously the central main hole. Possibly give both the orifices they came out a blow out with compressed air if you have access to it,

 

What was on this airscrew in the way of components when you pulled it out???

 

Dunno if it wouldn't maybe be a blocked gas cap breather..Undo the tanks cap and try running the bike like that and see if anything changes.

Edited by Horri

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The "air screw" is a fuel mixture screw on XLs. Either one should have a spring, tiny washer and o ring that usually stays in the hole. Be careful all of them are there. Missing any piece can make the bike run poorly. All the passages in the carb bodies should be wired, washed and blown out just as the jets are.

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Plugged jet. Most likely left carb main or pilot. Clean em like Horri says. On my 87 xr, i can change all three jets without removing the carbs from the bike in about ten minutes. swapping to allen screws can make life easier but if you have the right size screwdrivers and a little finesse its doable with stock phillips heads. That is if there not too tight.;)

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Garth: Didn't check the spark. Probably should do that. Put a new RIcky Stator in this thing right before I bought it from Famous Dave, the XL Crasher. Fuel venting is good, as is the filter. First thing I checked was that gas was getting to the bowls. It wuz.

 

After removing the air screw it had the spring on it. In my infinite wisdom and frustration I took the air hose to the air screw hole hoping to blow out any chunks. Nothing ricocheted off my forehead, so hopefully the metal and rubber washer are still in there. This thing ran fine until recently, so the original problem shouldn't be missing pieces. In the past I have used brake cleaner and compressed air to clean out my jets. Running wire through 'em seems so... harsh. I bought me a new-fangled 90-degree Craftsman ratcheting screwdriver. Should work on the bowl screws. I like the idea of using allens.

 

Thanks, Boys!

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Dangerous Dave is still with us, Bruce. Still gobbling up all the precious OT too. I've sworn off ocean fishing with him, and will only let him escort me to catch Salmon and Steelhead on the mighty Columbia River.

 

I've used 'ol D-Ray's videos for tips before. But I'm sure all XL600 owners like us would like to know this: How the h-e-double-hockey-sticks do you get the airbox back a whole inch??? I'm lucky to get it back a half inch. And that's removing the battery and using crow bars. They probably edited out the cussing and swearing that I have personally experienced doing carb work on these bikes. 

 

If I can't get the bowls and jets out with 'em on the bike, I'll call up D-Ray and have him stop on by and have him do it for me. I'm sure he won't mind.

 

Oooh, almost forgot. Anyone tried to gear one of these bikes down? I did a little single track riding last summer, and it was geared way too high for that. Constantly feathering the clutch at slow speeds. It has a 15-tooth counter sprocket. What would be better? a 13 or 14 tooth? I'm okay with losing a little top end speed. But I don't want to lose too much. 

Edited by Kerchak

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I had the same issues as the original poster. I've found out it's my piston.

So I need to buy a new piston for my '83 XL600R.

The old one is an aftermarket and says 0.40 (I'm in Arizona) I believe that to be the 101.00mm. I will measure to double check.

I'm of the understanding that I will need to buy say the Wiseco 102.40mm piston and bore the cylinder chamber to fit, is that correct?

What jet size should I use when I do, 55-150?

Thanks in advance to both questions and if anyone knows of a cheap piston somewhere!

Rossi

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I had the same issues as the original poster. I've found out it's my piston.

So I need to buy a new piston for my '83 XL600R.

The old one is an aftermarket and says 0.40 (I'm in Arizona) I believe that to be the 101.00mm. I will measure to double check.

I'm of the understanding that I will need to buy say the Wiseco 102.40mm piston and bore the cylinder chamber to fit, is that correct?

What jet size should I use when I do, 55-150?

Thanks in advance to both questions and if anyone knows of a cheap piston somewhere!

Rossi

did you swap to a single carb head? What exhaust, mods etc? Your bike had dual carbs stock so it has one pilot and two smaller main jets.

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Hey buddy, thanks for the reply. I have the standard dual carbs, no air box just two uni pods. To say I have a basic exhaust is an understatement, headers into a $35 back box with holes galore (not the best setup) I have two jets which I think are standard, but I have an '83 and for some reason I think there is a pilot jet, but some part of me thinks there isn't. I live in Phoenix, so hot as hell and about 1800ft above sea level. I think I'll do the piston and run with the jetting I have and go from there. Sound sweet?

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I do believe .040 over equals 101 mm for this bike. Stock bore is 100 mm. I'd say have a shop mic the bore, make sure it is not tapered or scored. If it's still square and not scored, you should be able to do a piston/ring kit after honing the cylinder. On the '85 that I'm rebuilding, I found a ton of Wiseco kits for around $150. That's the cheapest I've found. What was wrong with the piston? I haven't done a compression check on my bike, but in trying kicking it over, it sure seems to have enough.

 

I pulled the plug and it looked okay. Re-gapped it (it was within tolerances - .032) put it back in and the bike ran the same.

 

So I removed the carbs and went through them. The main jet did have some cloggage. When I viewed the jet after removal the hole was really tiny. I went to take a photo of it and suddenly the blockage was gone. So, if all it took to unclog it was merely removing it, I'm not so sure it was really a problem. I cleaned the entire set out, blasting all the jets and channels with brake cleaner and then compressed air. Tossed 'em back in and it seemed to run better at first, but still had that mid-throttle blaaaahhhhhh. Keep it open halfway and the bike dies. I fiddled with the air screw settings-no difference.

 

Took it for a run down the street. Got to the end of the street (tenth of a mile) and she just flat died. I was able to milk it home.  Because it got noticeably worse after getting warm/hot, I'm now of the opinion that it may be electrical. Pulled the CDI off for a quick swap out with the one from the '85, but it's in a box somewhere in the shop. Thought I had all that sh*t in one spot.

 

I'm running out of ideas. Valve lash? Pulse generator? It's got a newer Ricky Stator so that should be good. Fires up just fine.

 

I'm getting close to *gasp* "taking it in to have it looked at".

Edited by Kerchak

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Kerchak, did you ever varify good fuel flow from the petcock all the way to the carb? I know it was mentioned earlier but i never saw a response. When you pulled the jets did you also pull and clean the tubes that the main jets screw into with the tiny holes in it?

Not doubting your work or anything, just trying to be thorough.

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Rossi, yeah your bike has three jets, a pilot jet and a main jet in the left carb and just a main jet in the right carb. Your bike should start and run with the stock jetting after you do the piston work but even at your altitude and temps i would bet you could benefit from slightly more fuel. A good starting point is 55 pilot and 125 in both mains. The size is stamped on the side of the jets. After that just post any questions and someone will help you get it dialed in right.

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Well, she's a runnin' again. Here's how it came about: I knuckled under and dragged the thing to the local Honda shop. They were willing to give it a listen. "They" being a twenty-something kiddo who had never heard of an XL600. My confidence waning, I fired it up and was witness to a series of "Hmmmm's", "Huh's", and scratching of a pubescent chin. Junior had couple quick conferences with the main man, who was hiding around the corner, and they concluded that it was definitely a carburetion problem, due in fact to the air screw issue. That being it didn't matter where the thing was set (or even installed), the bike ran the same: uber crappy.

 

Armed with this wealth of knowledge I dragged the thing to a local privateer mechanic, the same dude that rebuilt the carbs when Demon Dave was the proud owner. Yeah, he recognized it, even remembering it needed a stator. After a short reunion of reminiscing, Dude listened to it, ran it down the street and after experiencing no issues, pronounced it fit for duty. He did say that I should check the petcock screen for gunk.

 

I decided at that point to stuff a new spark plug in, just for fun. That done and seeing no improvement, I decided to pull the carbs off, again, and replace them with the set off the '85. After all, I already had gone through them and that bike ran well for the four minutes it took me to decide it needed rebuilding. So that I did, finding that if you do something over, and over, and over, and over again, you get pretty good at it. An hour later I had the new set in. I also cleaned out the petcock screen (it was fine). 

 

Lo and behold, it fired right up and after a little coughing and puking, ran like a top. Ran it up and down the highway for a couple miles, and gave it the stamp of approval. Looks like the bowl gaskets leak, but I'm okay with that for now.

 

Do I know what was wrong? Nope. Don't care at this point, but I will tear the original carbs down, again, and clean 'em out, again. I've heard of some guys removing the jets and related paraphernalia and dropping the whole thing in a big pot of boiling water for eight hours or so. I may try that. Mama will love it simmering away right next to the Alfredo sauce.

 

But for now my Baby's back and I'm going riding. Now that the sun is gone and given way to more typical Washington Springtime weather, that is.

 

Thanks for all the suggestions, guys!

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Here's a plan: slap the bad carbs on the rebuild project bike, sell it to Dave for a premium, and take out an insurance policy on Dave. Profit.

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Diamond Dave has sworn off bikes for good. Being laid up for four months in recovery will do that to some people, I guess. When I mentioned "his bike" had died on me and left me stranded, he announced the 90-day warranty was up, a wry smile etched on his face. Didn't plan on the project bike being a parts bike, but that's how it's turning out. 

 

Did I mention how much I love the dual throttle cable set-up on this sucker? Oh, yeah, love in the first degree. Intermixed with all this other hocus-pocus, I determined that the throttle cables needed replaced. The ones on Dave's bike clearly weren't the right ones. Instead of routing through the forks, they went to the right of the whole steering set up. All fine and dandy unless you make a hard right turn. Tends to put the 'ol pinch on the cables. Tried re-routing them through the forks, but they were too short. Since the bike was gonna be torn apart anyway, I decided to replace the cables. The first set I got from the Honda shop, Parts Unlimited brand, did not fit. They were longer than Dave's cables, so I thought I was golden. I was more like pewter. The pull cable was okay, but trying to get the push cable on was a friggin nightmare. The cable mounts at three points: Throttle grip, cable mount on the carb body, and carb assembly. I could get any two points attached just fine. The third point, regardless of where I tried, was nearly impossible. When I could get it on by using the stronger back muscles and a great deal of strain, the throttle was bound like a convenience store clerk after a robbery. Honda swapped out the cables for a set of Motion Pro cables. Their length was a little longer, but it made no difference. I finally decided that a single pull cable will work just fine for me. And it does.

 

Any opinions on the single cable set up, or how to get the push cable on? And yes, they are different cables with different part numbers.

 

Ma halo. 

Edited by Kerchak

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