Stuttering while accelerating?
Collapse
X
-
1981 XS1100H Venturer
K&N Air Filter
ACCT
Custom Paint by Deitz
Geezer Rectifier/Regulator
Chacal Stainless Steel Braided Brake Lines
Chrome Front Rotor & Caliper Covers
Stebel Nautilus Horn
EBC Front Rotors
Limie Accent Moves On In 2015
Mike -
Yes, DiverRay, I am talking about the advance unit, nothing to do with carbs in my posting, thanks for noting that.
Question: What makes an iridium plug more prone to fouling if mixture is off?Howard
ZRX1200
BTW, ZRX carbs have the same spacing as the XS11... http://www.xs11.com/forum/showthread.php?t=35462Comment
-
Mixture screws
OK. I am officially confused. There are guru conflicts.
One says adjust to highest vacuum.
Another says turn towards closed until the RPM drops, then open 1/8 turn.
Third says adjust to highest RPM.
These all came from the most trusted and experienced sources on this board.
As a side note, I'm having economy/black plug issues. I had mine set by the highest vacuum method. That turned out to be 1.5 turns out on each. Thankfully, I don't think this setting is very critical because after review of what the most trusted gurus say, I don't know. 1.5 to 2.0 turns out is probably good enough.Marty (in Mississippi)
XS1100SG
XS650SK
XS650SH
XS650G
XS6502F
XS650EComment
-
Marty, We don't always agree because we all learned from different people. Highest idle and highest vacuum are both VERY CLOSE. The bike will run well set with either method, just chose the one you know best.
I do think if he has K&L jets, that could be part of the problem. There IS a difference in the jets, and Yamaha and Mikuni had things correct from the factory. Changing jet sizes should be just that, one step up or down from what is in there. The size is based of flow with the mains, and MIXING THE FLOW with the pilots. If they were not produced correctly, they will not work correctly, IMHO.Ray Matteis
KE6NHG
XS1100 E '78 (winter project)
XS1100 SF Bob Jones worked on it!Comment
-
They are all correct.
What each of those methods is trying to get to is the smoothest, slowest idle speed with the least amount of gas going into the engine. At that point, the engine is putting out the most power, (creating suction), with the smallest throttle opening, (fuel burned).
1: When using highest vacuum, you usually end up reducing the idle speed a time or two to get to highest vacuum and correct idle speed. This is the best way, in my book.
2: The second method assumes you are at lowest idle speed, and you choke off idle fuel flow until it stumbles, then open enough to smooth it out, and re adjust the speed up to specs.
3: The third assumes that the idle speed is correct, and you adjust the mixture screw to get highest idle speed, which means you go back and set the idle speed down and adjust mixture again, and again, etc. And there you are, back at two.
Just be sure that all others aspects of the engine are correct. Timing, valve clearance, ignition condition, plugs, compression, etc.
CZComment
-
Ray,
You're right, of course. I'm running rich when I used to be running lean. My jetting is nearly stock and all Mikuni. I used to be lean across with 110-120-120-110 that was in the bike when I bought it in '03. Now, it's 110-115-115-110 and rich. Mix screws at 1.5.
Folks are too quick to mess with jets when they should be left alone. As for me, my solution may yet be the spark and possibly my #4 float as I has a broken float post welded.
Point is, I'm not going to mess with the jetting and most folks should do the same, IMHO.
Back to the topic. Thanks!Marty (in Mississippi)
XS1100SG
XS650SK
XS650SH
XS650G
XS6502F
XS650EComment
-
I finally got back to the bike this week. Because of the fowling plugs on #1 and #2 and not #3 and #4 I decided to re-sync the carbs. When I hooked up my Motion Pro balancer it went nuts. Vacuum was extremely high on the left side. When I tried to balance it over the idle started to climb drastically. By the time I got the idle down it was too late. About half the fluid in the balancer had been sucked out. After doing some research on the web it turns out I probably had an air leak in the o-rings of the balancer. I took it apart and cleaned and re-seated the tubes and O-rings. I washed all the remaining fluid out. I had read in some forum somewhere that the fluid is glycol based and you could use auto antifreeze as a substitute instead of paying the rather pricey cost of the pretty blue replacement fluid from Motion Pro. I figured nothing to loose by trying it. So I refilled the balancer too the correct levels and it works great. Just like new. If anything the fluid seems a bit more stable. Less bounce in the readings. I re-balanced the carbs. Adjusted the idle mixture by ear and she is running good. Idle nice and smooth. But I still have the stutter @ 4500 rpm. Dam. Researching other possible causes. Maybe carb float level. Maybe main jet needle setting. I have never done a valve adjustment since I owned it. That's the next priority.Graham in Surrey, B.C., Canada
1979 XS1100 Special.
Mac 4 into 2 chrome exhaust.
Dyna high performance coils.
Drilled air box.
K&N air filter.
Pics https://www.dropbox.com/sh/4tpyuurw3...XjCLWeTVa?dl=0Comment
-
I have never done a valve adjustment since I owned it. That's the next priority.
You NEED to adjust the valves and check the timing BEFORE trying to sync the carbs! I would start with a valve check, then check the timing and advance per the Yamaha manual. After that, you can check the sync. That may NOT solve the problem, but it WILL get you closer to it.Ray Matteis
KE6NHG
XS1100 E '78 (winter project)
XS1100 SF Bob Jones worked on it!Comment
-
You NEED to adjust the valves and check the timing BEFORE trying to sync the carbs! I would start with a valve check, then check the timing and advance per the Yamaha manual. After that, you can check the sync. That may NOT solve the problem, but it WILL get you closer to it.1979 XS1100F
2H9 Mod, Truck-Lite LED Headlight, TECHNA-FIT S/S Brake Lines, Rear Air Shocks, TKAT Fork Brace, Dyna DC-I Coils, TC Fuse Block, Barnett HD Clutch Springs, Superbike Handlebars, V-Star 650 ACCT, NGK Irridium Plugs, OEM Exhaust. CNC-Cut 2nd Gear Dogs; Ported/Milled Head; Modded Airbox: 8x8 Wix Panel Filter; #137.5 Main Jet, Viper Yellow Paint, Michelin Pilot Activ F/R, Interstate AGM Battery, 14MM MC, Maier Fairing, Cree LED Fog Lights.Comment
-
I think once you have checked the valve clearance, you will no longer be intimidated by the task. The same goes for swapping shims. I believe there may be a lot of these machines out there that have never had the valves checked or adjusted, due to the intimidation factor.Marty (in Mississippi)
XS1100SG
XS650SK
XS650SH
XS650G
XS6502F
XS650EComment
-
"Back in the day"
OK. I am officially confused. There are guru conflicts.
One says adjust to highest vacuum.
Another says turn towards closed until the RPM drops, then open 1/8 turn.
Third says adjust to highest RPM.
These all came from the most trusted and experienced sources on this board.
As a side note, I'm having economy/black plug issues. I had mine set by the highest vacuum method. That turned out to be 1.5 turns out on each. Thankfully, I don't think this setting is very critical because after review of what the most trusted gurus say, I don't know. 1.5 to 2.0 turns out is probably good enough.
The procedure was simple - adjust screws to best vacuum, then turn each screw back in to drop the idle RPM by 50 RPMs (GM cars and trucks). The goal was to keep exhaust emissions in check (lean). I'm guessing that Yamaha was required to do same.Last edited by MPittma100; 04-16-2015, 03:18 PM.1981 XS1100H Venturer
K&N Air Filter
ACCT
Custom Paint by Deitz
Geezer Rectifier/Regulator
Chacal Stainless Steel Braided Brake Lines
Chrome Front Rotor & Caliper Covers
Stebel Nautilus Horn
EBC Front Rotors
Limie Accent Moves On In 2015
MikeComment
-
Back in 1975 when catalytic converters and the little plastic limiter caps on the fuel/air mixture screws invaded our automotive lives, there was an OEM prescribed method of adjusting these screws. It was called the "lean drop" method.
The procedure was simple - adjust screws to best vacuum, then turn each screw back in to drop the idle RPM by 50 RPMs (GM cars and trucks). The goal was to keep exhaust emissions in check (lean). I'm guessing that Yamaha was required to do same..
That same 'lean drop' method, if choosen is done same way on our Mikunis.
Once going back in with mixture screw listening for slighest rpm drop(low rpm tach is better), back mixture screw out 1/8 to 1/4 turn at maximan.
Having used this procedure for decades in the automotive world, it was brought to my attention several yrs. back by a local bike tech. here who was ironicly factory trained on the XS11 series back in the day, that clued me to the above procedure.
He now has his own shop with a large backlog of nice looking customer classic scoots to be worked on, and is very particular bout the work he does.
Knowing him for almost twenty yrs., and now having his own shop made me lazy enough to just pull my fairing, leave it there to cool overnite and let him swap out shims for valve adj. Best part, is he doesn't disturb cam journel caps changing shims.81H Venturer1100 "The Bentley" (on steroids) 97 Yamaha YZ250(age reducer) 92 Honda ST1100 "Twisty"(touring rocket) Age is relative to the number of seconds counted 'airing' out an 85ft. table-top.Comment
-
I'm having a very similar issue with my 1980 xs11 (SG). But I think mine is due to fuel starvation, though I can't exactly figure it all out.
First off, my bike has K&N pod filters. Cleaned within the past week so air should be flowing well. I did open up the carbs shortly after I bought it a few months ago and they were super clean. I mean, I'd eat off the surfaces, and no corrosion on the jets or other brass components. I also chopped off my exhaust shortly after I bought it.
I did NOT, however, think to look to see what size jets were installed, thought the previous owner said he was almost certain they were stock.
Now is when I'd expect someone to say "Well you're getting too much air due to the added flow from the chopped exhaust and pod filters, you idiot!"
But here's the kicker. At higher RPM's, I'm fouling out plugs. I have to turn the mixture screws almost all the way in just to keep from fouling them out at highway speeds (rich), but at idle, the exhaust is popping (lean). Does this make sense to anyone?
In my opinion, if I'm fouling out plugs only at high RPM's, it seems I have dirty filters, but I just cleaned them using the proper method.
Oh, and even though I'm getting the seemingly rich burn at higher RPM's, I'm still getting that stuttering problem when accelerating at highway speeds that the OP has described.
Thanks for all the help, in advance.XS SpecialComment
-
I'm having a very similar issue with my 1980 xs11 (SG). But I think mine is due to fuel starvation, though I can't exactly figure it all out.
First off, my bike has K&N pod filters. Cleaned within the past week so air should be flowing well. I did open up the carbs shortly after I bought it a few months ago and they were super clean. I mean, I'd eat off the surfaces, and no corrosion on the jets or other brass components. I also chopped off my exhaust shortly after I bought it.
I did NOT, however, think to look to see what size jets were installed, thought the previous owner said he was almost certain they were stock.
Now is when I'd expect someone to say "Well you're getting too much air due to the added flow from the chopped exhaust and pod filters, you idiot!"
But here's the kicker. At higher RPM's, I'm fouling out plugs. I have to turn the mixture screws almost all the way in just to keep from fouling them out at highway speeds (rich), but at idle, the exhaust is popping (lean). Does this make sense to anyone?
In my opinion, if I'm fouling out plugs only at high RPM's, it seems I have dirty filters, but I just cleaned them using the proper method.
Oh, and even though I'm getting the seemingly rich burn at higher RPM's, I'm still getting that stuttering problem when accelerating at highway speeds that the OP has described.
Thanks for all the help, in advance.79 XS1100SF k&n pod filters
emgo shorty mufflers (w/o baffles)
chopped rear
springer seat
led turn signels
led brake light
side mount verticle plate
drag bars.
86 Suzuki Intruder VS700
8" biltwell chumps
chopped rear
nasty twins drag pipesComment
Comment