3k Stumble

[HalfCentury]

You should also consider replacing the enrichment (choke) shaft seals.

[HalfCentury]

And you may want to consider ignition coils. See the thread below.

http://www.xs11.com/forum/showthread.php?t=46678

[mschor]

I tuned my bike in the sidestand once not thinking, it makes a difference

[spectra]

You may be able to spray starter spray around the throttle shaft seals while the engine is idling to see if the idle changes. The idea is the the starter spray fumes get sucked into the leaky throttle shaft seal(s) causing idle RPMs to increase.

Oh I have already done the starter fluid trick as my boots were not 100% tight. Starter fluid sprayed at the carbs now does nothing.

I tuned my bike in the sidestand once not thinking, it makes a difference

I pretty much have the bike at about 98% level. I have to be careful as it will tip if I push it to hard........I just did that for tuning purposes......

[TopCatGr58]

Ok back together and it runs great in the garage.........take it out and falls on its face then goes but stumbles a bit till about 3 to 4 K. If I stay in the higher rpm range it runs fine.

Suggestions on where to go next ?

Hey Spectra,

Just reread this thread, gleaning key points.
1) Removed "kit" jets and replaced with OEM Mikuni jets/pilot and mains.
2) Cleaned carbs, replaced intake boots, NO vacuum leaks confirmed.
3) Carbs synched, ignition system working....however didn't see if ALL 4 pipes confirmed HOT after warmup by spritzing with water, should sizzle off almost instantly, if one doesn't sizzle, have a cold cylinder possibly not firing.

Engine will rev easily in neutral, but be weak under load if only on 3 cylinders.

However, when riding, says it comes alive at 3-4+K rpm, so probably hitting on all 4 at that level and above.

Configuration=aftermarket 4-1 pipes. They scavange very good, but most are tuned for increased performance in the upper rpm range, not so much for the lower rpms. Many folks over the years reported LOSS of low rpm grunt after putting on 4-1 pipes, but also Pod filters. This is mostly due to a change in airflow which seems to lean things out a bit.

The jetting "guide" states 2 jet size up for each MOD ie, pipes, Pods, and when more than one, add them, but subtract 1 size.

I got my 81SH NEW, and soon after I got it back to the USA from my Duty Station in JAPAN, like an ignorant "yute" I got a set of 4-1 pipes and put on it thinking that it would help it run better and stronger...WRONG. Yamaha put a lot of time, work, research into developing the intake and exhaust systems to provide the best "ALL AROUND" performance, not necessarily the fastest quickest TOP END, not the strongest tree trunk pulling LOW END, but a good compromise for a variety of riding styles for folks.

I didn't REJET mine for 9 years because I ONLY put on 4-1 pipes. It came stock with 110's across all four, and it still seemed to be able to get to redline, cruise, and still take off from a standstill decently. It then died/transmission, sat for 9 years until I gained both financial ability and GARAGE to be able to rebuild it. I did an 1179 cc big bore kit, and put PODS on it, so I THEN rejetted it but only to 115's. I then did a DYNO run after breakin, and it revealed that I could go up another main jet size, as well as pilot jet size. Prior to this, my spark plugs looked mostly WHITE with just a hint of color. I finally did the full rejet to 45 pilots and 117.5 mains, and have decent plug color, strong throttle response to redline, BUT it still isn't quite as strong at the very low 1500-3500 rpm range. But I know that the charging system doesn't start providing proper charging current until at least 2500 rpm, and so I never run it below that anyways. I like the quicker throttle response in whatever gear I'm in when running ~3000 rpm or more, as well as the engine braking affect when I back off the throttle vs. having to use the brakes so much.

SO...after saying all that, your PILOT circuits may still not be as clean as they should be. And you may need to increase your jets a little. After doing the lean drop method, see how it responds to low throttle. If still a little sluggish, try turning each pilot screw out 1/2 turn and repeat test. Just be aware that once you get to about 3.5 to 4 turns out, the guidelines say you should go up a pilot jet size. But even after that, just be aware that you may still not have as strong of a low rpm throttle response as a STOCK bike with OEM pipes.

T.C.

[spectra]

Hey Spectra,

Just reread this thread, gleaning key points.
1) Removed "kit" jets and replaced with OEM Mikuni jets/pilot and mains.
2) Cleaned carbs, replaced intake boots, NO vacuum leaks confirmed.
3) Carbs synched, ignition system working....however didn't see if ALL 4 pipes confirmed HOT after warmup by spritzing with water, should sizzle off almost instantly, if one doesn't sizzle, have a cold cylinder possibly not firing.

Engine will rev easily in neutral, but be weak under load if only on 3 cylinders.

However, when riding, says it comes alive at 3-4+K rpm, so probably hitting on all 4 at that level and above.

Configuration=aftermarket 4-1 pipes. They scavange very good, but most are tuned for increased performance in the upper rpm range, not so much for the lower rpms. Many folks over the years reported LOSS of low rpm grunt after putting on 4-1 pipes, but also Pod filters. This is mostly due to a change in airflow which seems to lean things out a bit.

The jetting "guide" states 2 jet size up for each MOD ie, pipes, Pods, and when more than one, add them, but subtract 1 size.

I got my 81SH NEW, and soon after I got it back to the USA from my Duty Station in JAPAN, like an ignorant "yute" I got a set of 4-1 pipes and put on it thinking that it would help it run better and stronger...WRONG. Yamaha put a lot of time, work, research into developing the intake and exhaust systems to provide the best "ALL AROUND" performance, not necessarily the fastest quickest TOP END, not the strongest tree trunk pulling LOW END, but a good compromise for a variety of riding styles for folks.

I didn't REJET mine for 9 years because I ONLY put on 4-1 pipes. It came stock with 110's across all four, and it still seemed to be able to get to redline, cruise, and still take off from a standstill decently. It then died/transmission, sat for 9 years until I gained both financial ability and GARAGE to be able to rebuild it. I did an 1179 cc big bore kit, and put PODS on it, so I THEN rejetted it but only to 115's. I then did a DYNO run after breakin, and it revealed that I could go up another main jet size, as well as pilot jet size. Prior to this, my spark plugs looked mostly WHITE with just a hint of color. I finally did the full rejet to 45 pilots and 117.5 mains, and have decent plug color, strong throttle response to redline, BUT it still isn't quite as strong at the very low 1500-3500 rpm range. But I know that the charging system doesn't start providing proper charging current until at least 2500 rpm, and so I never run it below that anyways. I like the quicker throttle response in whatever gear I'm in when running ~3000 rpm or more, as well as the engine braking affect when I back off the throttle vs. having to use the brakes so much.

SO...after saying all that, your PILOT circuits may still not be as clean as they should be. And you may need to increase your jets a little. After doing the lean drop method, see how it responds to low throttle. If still a little sluggish, try turning each pilot screw out 1/2 turn and repeat test. Just be aware that once you get to about 3.5 to 4 turns out, the guidelines say you should go up a pilot jet size. But even after that, just be aware that you may still not have as strong of a low rpm throttle response as a STOCK bike with OEM pipes.

T.C.

Thanks for the heads up and yes one of the reasons for taking the carbs off is I read about turning the pilots out a little and wanted to try it. I am not a fan of the exhaust but its whats on there so..........I live with it for now. Finding stock I don't think will happen.......

All 4 fire and pipes are hot as I checked that part and picked up a box fan and run it all the time while playing with it.

Hopefully I can figure it out this weekend. Just found a pile of parts on craigslist for 150 bucks........new 4 into 1 exhaust, OEM parts in bags.......they say its a complete bike in parts........will see......

[spectra]

Quick question if anyone is listening.......pulling the carbs apart t onight and wonder if I should adjust the fuel bowls? I did re adjust them to the clymers specs as they were off by a bit.

Thanks!

[TopCatGr58]

Not sure what you mean by adjust the FUEL BOWLS?? If you mean the FLOATS, then you can "play" with them until you get some larger jets.

From what Brant/Motoman has said, 1mm of float height adjustment can be up to 3mm of actual fuel level variation. Stock setting is 25.7mm +/-1mm. Setting them LOWER(carbs upside down going from 25.7 to 24.7) will richen up the fuel level, but I think mostly for the mains. The pilots get their fuel THRU the mains and the sharing tunnel between the main/pilot jet towers....that's why there's a sealing screw on the end of the pilot jet tower. The pilot jet air/fuel mixture is mostly controlled with the pilot jet SCREW on the top of the carb body.

T.C.

[spectra]

Not sure what you mean by adjust the FUEL BOWLS?? If you mean the FLOATS, then you can "play" with them until you get some larger jets.

From what Brant/Motoman has said, 1mm of float height adjustment can be up to 3mm of actual fuel level variation. Stock setting is 25.7mm +/-1mm. Setting them LOWER(carbs upside down going from 25.7 to 24.7) will richen up the fuel level, but I think mostly for the mains. The pilots get their fuel THRU the mains and the sharing tunnel between the main/pilot jet towers....that's why there's a sealing screw on the end of the pilot jet tower. The pilot jet air/fuel mixture is mostly controlled with the pilot jet SCREW on the top of the carb body.

T.C.

Stupid me............yes floats.........they were off and set them to what clymers said. that 25.7 sounds familiar. They were higher from what I remember so I think they were trying to lean it out maybe ?

[TopCatGr58]

X-pipe system

Here's the link to the website, it's actually in California!

http://www.x-pipe.com/japanese.html

Clicked on the LINK for Yamaha, lists 78-81 XS11 and 82XJ11. They want $899.95 for a set !

T.C.

[spectra]

Here's the link to the website, it's actually in California!

http://www.x-pipe.com/japanese.html

Clicked on the LINK for Yamaha, lists 78-81 XS11 and 82XJ11. They want $899.95 for a set !

T.C.

Those are MAXI prices

They cant even spell Maxim right Maxum................

I have one of those to but I only paid 250 for it.............not going to triple the price on exhaust.........

[motoman]

Not sure what you mean by adjust the FUEL BOWLS?? If you mean the FLOATS, then you can "play" with them until you get some larger jets.

From what Brant/Motoman has said, 1mm of float height adjustment can be up to 3mm of actual fuel level variation. Stock setting is 25.7mm +/-1mm. Setting them LOWER(carbs upside down going from 25.7 to 24.7) will richen up the fuel level, but I think mostly for the mains. The pilots get their fuel THRU the mains and the sharing tunnel between the main/pilot jet towers....that's why there's a sealing screw on the end of the pilot jet tower. The pilot jet air/fuel mixture is mostly controlled with the pilot jet SCREW on the top of the carb body.

T.C.

All true T.C., except for the fuel levels in bowls affect the flow RATE and WHEN through the pilot jets. Remember too, that pilot circuit just maxes out when venturi velocity determines the need for more fuel, then that velocity causes fuel to be added/drawn through main circuit ADDING fuel to the starving pilot circuit. In other words, pilot circuit is ALWAYS flowing fuel no matter rpm range, and main circuit is ADDING to the needed fuel depending on rpm range/venture velocity. So, with all that, fuel levels in float bowls DO affect fuel flow rate through BOTH pilot and main circuit. This all is also very true in the carbureted automotive world. I just state all this since in the professional automotive world for some 2+ decades I rebuild and set up carbs for many different applications(on-road,track, and off-road).

[3Phase]

Here's the link to the website, it's actually in California!

http://www.x-pipe.com/japanese.html

Clicked on the LINK for Yamaha, lists 78-81 XS11 and 82XJ11. They want $899.95 for a set !

T.C.

For roughly $1000 without shipping, there's a place in Germany that was building stainless steel exhausts for the XS1100 Standard and Special. Look on the left-hand edge of the page, click the on the "XS-Shop" button and a picture/link for their exhaust system is at the top of the next page that opens:-
http://www.xs1100-frw.de/

[spectra]

Well this thing is about to piss me off....................I cleaned the carbs put it all back together and it runs worse now............I think this thing is cursed and that's why I got it at such a good deal.........

Beating my head against the wall now.......carbs are off again and going to go through them one more time in the morning.......if that doesn't help well there may be a XS for sale cheap.........tired of dealing with it when its a simple fix I am sure.

Hell my other bikes were not half is hard to deal with.......

[DiverRay]

Get a new set of spark plugs and start from there.
Do a throttle chop, read the plugs. Rich or lean? adjust ONE item on the carbs, float level, idle mixture screw, etc., then try again.
If you are doing more than one thing at a time, you will NOT figure out what is wrong. Trust me, BTDT more than once.(I'm a slow learner sometimes)