K&L carbatrocity?!

[tommystinson]

OK, here's the deal. I bought carb rebuild kits from cycle recycle and installed them. It doesn't run well. Not horrible just off idle, hitches and coughs until just about redline, then moves out pretty well. Of course I read about all the K&L problems AFTER I bought and installed them. Then I started reading threads about tuning, etc. and read about diaphragm trouble. Hey, no big deal. I'll just replace them, and rule that out as a problem. Holy crap! $100! Each?! I think they "drop" at the same rate, but the outer (1 and 4) slides look higher than 2 & 3. I'm a little nervous at this point. I'm a decent mechanic (used to spin wrenches on Acuras for a living) but this whole carb situation is out of my element. The details: '79 xs11sf, K&L carb kits, generic 4 into 1, cone filters (for initial easy access to carbs, will eventually return to stock) Octopus removed and plumbed diectly to tank, the top 2 tee fittings on the carbs are not connected to anything (they are just for breathing, arent they?) And finally, two more questions. What do I do with the crankcase vent hose for now? and what is the small diameter hose that appears to go into the middle gearbox? I can't seem to find it in the manual. Thank you in advance. I'm going to go stumble around the block on my bike for a while. Oh yeah, as if I needed to mention it, there's enough carbon on my plugs to have a BBQ.

[Bill]

Re: K&L carbatrocity?!

Tommy Stinson wrote:

• bought carb rebuild kits from cycle recycle and installed them. It doesn't run well. Not horrible just off idle, hitches and coughs until just about redline, then moves out pretty well.
• The details: '79 xs11sf, K&L carb kits, generic 4 into 1, cone filters (for initial easy access to carbs, will eventually return to stock)

In my most recent trip through "carb hell" on my '79 Standard, I did many of the same things you did. Here's what I can share from that experience and ones previous:

• I've used most of the parts in a K&L kit, though I can't vouch for the jets. Most people recommend using Mikuni originals. They're available for about $10/set by mail order.
• Using a 4:1 exhaust and "cone filters" without re-jetting can cause a lot of problems related to a lean condition, which would be consistent with your smoother operation at WOT. See Denny Zander's Jetting Recommendations to get an idea of the difference between stock jetting, and what would be required with your 4:1 exhaust and individual filters.
• Since you plan on eventually returning to the stock airbox, I'd put that back on and see how the bike runs. Be sure that the filter element is clean. On my bike, a very dirty element turned out to be causing many of the problems.

Keep us posted on your progress.

XSively,

[MartyA]

Hey Tommy, I draped my crank case vent hose over the back of the tranny.

[Snow]

Marty, did you put a filter on the end of the breather hose? I only ask b/c not only does the hose blow out, it also sucks in and you don't need particles in yer oil

[MartyA]

No, thought that there might be enough oil lining the insise to trap most dust particles. It keeps the gas tank overflow and the battery hose company.

The only problem I had was one oil change I had a brain cloud and put 6 qts of oil in. The XS finally blew out the Xsess all over the rear wheel. But you won't do that.

[tommystinson]

Something of an update. I found a vacuum leak. Not sure how I missed it, but the manometer attachment tube (does this have a real name so I don't sound like a dope?) for synching was uncovered on # 2 carb boot. Cobbled cap is now in order. Am I correct in the venting of the top two tees of the carb assy., or do they need actual "vacuum"? So it stumbles at idle, runs OK? at 3-5K, then stumbles again after that. I'm going to pull them off again and redo the bread tie trick. I guess a question would be, how do I know if it"s running well enough to justify a "real" sync ? If there is anyone within a couple hours of Utica or Albany who might might be willing to offer an "XS 101", I'll supply the adult beverage of choice (not while riding,of course) or Mallomars or whatever. Not that I wan't to avoid it forever, but I think I'm going to check out Merriam Cycles for a quote on rebuilding the carbs. Thoughts/Ideas/Experiences? Cowardly but pragmatic? Boy, I'm sounding a little pathetic... Oh yeah, what is "LOL"?

"It is sometimes necessary for a smart man to be drunk in order to spend time with his friends" E. Hemmingway

[TopCatGr58]

Hey there Tom,

That "vacuum port" you found on #2 carb, hopefully you're talking about the one closest to the engine, attached to the rubber intake vs. the other one on #2 that is part of the carb: that one on the carb is for the vacuum advance hose that goes to the left side of the engine. You will want to inspect that hose to ensure it doesn't have any cracks or leaks, and inspect the action of the advance unit to make sure it turns smoothly without hanging up anywhere, and that the vacuum module actually moves the advance plate when suction is applied to the hose(your mouth).

Next, you can take a piece of vacuum hose, put a thick screw in the other end of it to cap it off and put that on that vacuum port to cap it off. You can also find these at auto parts stores...I've seen them in the "help" section....all those little parts they have hanging on racks out on the floor!!

That little hose on your middle gear box is also a vent, it was usually held up just to the air near and under the gastank by a clamp that was near the gas tank hold down bolt. The larger one as several folks stated, is the engine vent, I have it draped down the back with the battery tube also, but I will probably get a fancier filter to put on it eventually, like #66 has.

I have an '81, but from what I've read here, those upper tubes are vented, no vacuum to be applied to them.

You're setup is exactly like mine, I've got Indy Filters, and No-Name 4-1 pipes. I ran stock jets for over a year with them, and didnt' really notice any problems, it pulled strong to redline, but my plugs were pristine white. I tore my carbs down and put them back together myself. Prior to working on my bike, I had only rebuilt auto carbs....2 barrels. It wasn't really difficult at all. DO YOU HAVE A MANUAL? After I put them all back together, I didn't even use a breadstick/wire....I just eyeballed them to get the butterflies visually synched. I still haven't broken down and gotten a vacuum gauge set to do a "true" synching since it runs and idles well!!

The jetting guide recommends going up a total of 3 sizes with our setup....so I went from 110's to 117.5, didn't change the idle/pilot jet, but did back the idle screws out over 3.5 turns vs. the 1.25 recommeded by the "book"...this was recommended to me by my local bike machine shop/motorcycle racer tech that bored my jugs for my big bore kit. This seems to work well here at sea level, but I've noticed some bogging problems at altitude....so I'll be adjusting them back in a turn or so to not have it run so rich when I go to rallies in the mountains. The 79 carbs were to have the 137.5 mains, at 2.5 per increment, 3 sizes up should be 145.

You state that the plugs are black/carboned up, and you have the K&L carb kit parts in them. Many have noted that the jets were not correct. Do you have your OEM jets? If so, I would recommend putting those back in, both Mains and Pilots, set your floats a few mm's lower=closer to the carb body than the 25.7mm the book states, to help richen the "lean" mains a bit. You probably already have a good "eyeball synch"; Clean or get a new set of plugs, and I would bet it would run much better than the K&L jets! You'll want to get it out on the road for a little extended run, not just putting around the block, so that engine can warm up and burn off lots of the old carbon in the clyinders, then get it home and check your plugs(some folks recommend an on the side of the road check after an under load throttle chop technique!?). Right now, I think your K&L jets are really messing you up and running you way too rich; using the OEM mains and pilot jets you will probably be a little lean, hence the suggested float adjustment, and suggest turning the idle screws out an extra turn to 2.25 or so!

WOW...sorry for the winded reply!! I'm sure you can do the carbs yourself. Good luck...keep us updated on your progress.
PS: LOL is Net Talk shorthand for "Laughing Out Loud", there's a tech tips note about many of the abbreviations we use!!

[tommystinson]

Thanks for your detailed response, TC! I think I've been approaching this in the wrong way, trying to get it to run right with the new K&L kits. I do have the OEM parts, but probably won't put those back in as they are a little chewed up, and would be even more difficult to remove next time. I'll purchase new Mikuni stuff and throw them in. It ran well/long enough for me to cripple my right wrist with that monstrosity of a handlebar. I'll keep you posted!