Possible fuel line issue?

[oldyam80sg]

Never had anyone except me go through this bike and touch the carbs since about 1986 . I have had my XS since 1986 so I think I know a thing or 2 about these bikes. I do have a Dynojet recalibration kit installed in 1986 by a Yamaha mechanic and the jets are Genuine Mikuni. There are no shops by me that will look at a bike this old. I have done the work myself with help from this forum.

[Larrym]

Larry I think personally you are leaving the choke on too long-3 miles and then half choke? Takes me usually about mere minutes before I go half choke and the maybe 30 seconds before choke is pushed all the way in. My plugs are nice and have a slightly tan color.

Larry I think personally you are leaving the choke on too long-3 miles and then half choke?

Full choke is used only to start and then mebbe 30 seconds later I go to half choke and drive away. (･‿･)

I DON'T ride/drive wit' full choke on....ever. ( •_•)

Bike had OEM/Mikuni jets when I first got it YEARS ago and that's just how it ran. NEEDED half-choke and minimum of 3 miles riding before it got to operating temp so's I could turn the choke completely OFF and engine ran/idled properly. 彡໒(⊙ᴗ⊙)७彡

The "Tell-Tale" fOaR when to turn the choke completely off was/is when I come to a stop and the engine is idleing FAST. Turn the choke off totally and then it idles at the prescribed 1000-1100 rpms. (^_^)

BUT when I bought/installed the Taiwan carb kit/jets? (O_o)

After I fixed the fuel level problem I ran it fOaR less than 20 miles wit' the Taiwan jets installed. (－‸ ლ)

Symptoms are detailed in the post you quoted. Mebbe something fOaR others to look at to explain why their bike ain't running like a super bike... ┐(´ー｀)┌

Bike NOW has OEM/Mikuni jets and it's running just like it did when I first got it and fixed the ignition problem. GREAT! (^_^)

Takes me usually about mere minutes before I go half choke and the maybe 30 seconds before choke is pushed all the way in.

THAT is the symptom I got when I had the Taiwan Jets installed...plus it wouldn't start w/o cracking the throttle to give it more air. Ran strong even when cold and NO CHOKE but was totally LAME when it finally got up to operating temp. (´～｀)

It was like riding an XS850 instead of an XS1100. (￣ヘ￣)

That's me...but IIRC, didn't you have someone go thru yur carbs and put in some aftermarket jets/needles? (⊙_ʖ⊙)

[oldyam80sg]

Starts ok. Idles pretty good. Then it doesn't take throttle well and won't rev well.

Be aware that my very own "usual" XS1100 Starts and runs well on full choke. Then I switch to half choke for about 3 miles before it's up to operating temp so's it can idle/run right and I turn the choke OFF to ride around all normal like, again...takes about 3-4 miles of running on half-choke to get to the proper temp to run right without choke. ໒(⊙ᴗ⊙)७

WITHOUT the choke and BEFORE that 4-5 miles? (O_o)

GUTLESS as a Ford Pinto runnin' on 2 cylinders. (－‸ ლ)

TLDR version- Idling in the garage ain't NEVER gonna get yur XS up to temp so's it'll pull/rev like it's s'posed to. (O_O)

Seems like pipes are heating up pretty similar. I can do a better check on that.

Iffin' you don't got's an Digital IR Thermometer? (O_o)

THANK YOU. They's mostily made in China using stolen patents. (●´⌓`●)

Don't EVER touch those pipes wit' yur fingers. Use a water bottle to spray'em and watch to see how fast the mist boils/flashes off. OR NOT in the case where's one pipe/cylinder ain't playin' well wit' they others. ( ´ Д `)ﾉ

Original carbs, I assume the vents lines are the ports just to the right of my index finger in the 2nd pic. Open and no hoses on them.

Correct. (^_^)

Usual to put some kinda short line wit'a filter on'em but that's down the road a ways? (O_o)

It doesn't seem like it acts like the video from above.


That's GOOD. (^_^)

Mainly cuz the reason so many bikes run like the one in the video is due to cheap Taiwan Carb kits with bad needle/seats fOaR the floats. You set the floats to the right height like yur s'posed to yet the fuel levels in the bowlz are WAAAY off and usually so high the gas is just splattering in thru all the orifices in drops/splatters instead'a a fine MIST in the correct right ratio. (☉_☉)

Some of the "symptoms" when jets from the the Taiwan Kits be installed? (O_o)

1. WON'T start w/o cracking the throttle to give mOaR air. Leave the throttle closed and you'll crank till the battery just DIES. (*′☉.̫☉)

2. After 2 minutes of warm-up/idleing in the driveway you CAN turn the choke completely off and drive away all normal like. But that's only because the Taiwan jets are so RICH it's as if you NEVER turn the choke off anyways.... (－‸ ლ)

3. At around 5-7 miles of actually riding and when trully at operating temp? (O_o)

Below 4k rpm, twist the throttle a bit and it'll NOT accelerate. It'll try to STAY at the speed you are or even SLOW DOWN/BOG. ( ˶⚈Ɛ⚈˵)

4. Cut the throttle too quickly at 4k rpm or above? (O_o)


p-p-p-p-Buh-OOOM! As in much more than an annoying popping out the exhaust. A REAL ASPLOSION which iffin' you got's slide-on/clamp mufflers will blow'em off iffin' the clamps an't tight. ┐('д')┌


You SURE that the lips of the pod filter(s) ain't fully or partially obstructing any of the CRITICAL air holes around the outside of the carb inlet bell? (O_o)

My suggestion is to go fer a ride. 1/2 choke for about three miles then choke OFF.

Might be this simple. (O_o)

Larry I think personally you are leaving the choke on too long-3 miles and then half choke? Takes me usually about mere minutes before I go half choke and the maybe 30 seconds before choke is pushed all the way in. My plugs are nice and have a slightly tan color. OP should look at what the plugs look like. Are the carbs cleaned? Remember no carb cleaner in the bottle will help if other things are dirty. And then are the carbs even synced? What pilot and main jets are in the bike?

[oldyam80sg]

I have a 1979 XS1100 special. I hardtailed the rear and made a chopper out of it and put a harley tank on it. I have pods and custom 4 tube exhaust with no mufflers. I had Sigma get a jet kit for me and I installed it. I also put in new diaphragms and the bike still isn't running right. I currently have a on/off/RES petcock on it (not factory) into a 1/4" hose into a T into two 1/4" fuel lines and then into the carbs. Could it be the way I have the fuel lines running? I bought a Y to try, but I figured I would ask here first to see if anyone has run into this before. Do I need a different pitcock? Two petcocks into two fuel lines? I really don't want to do that, because I have a sick paint job on the tank. At times, like twice run pretty good so not sure if the fuel lines get air in them or don't flow very well. Here is a pic of the tank. You can see the petcock down on the left side. I will try and upload some pics of the fuel line situation tonight. I gotta think some of you have run different tanks and have a fix. Please help. So close to having this project ready to ride.

Looking at this pic-where is the vacuum cap? Bike will run like crap with this missing.

[Larrym]

Do not remove the pickup coils. You will not be able to just bolt them back in. They do not wire to the main coil. They wire to the ignition module who then sends grounding signals to the coils (the coils always have +12v when the key is on).

Very good and WISE advice, Deebs. (･‿･)

They wire to the ignition module who then sends grounding signals to the coils

Very important fact to know and use iffin' yur gonna do a functional test of the ignition coils on the bench or "in situ" (on the bike...).

I mean, you can make/break the circuit from the positive side of a GOOD ignition coil till the cows come home but NEVER get'em to make a spark. ( •_•)

[DEEBS11]

Do not remove the pickup coils. You will not be able to just bolt them back in. They do not wire to the main coil. They wire to the ignition module who then sends grounding signals to the coils (the coils always have +12v when the key is on).

[bikerphil]

The top P/U coil is cylinders 1+4, the bottom is 2+3.

This is the path of the harness starting at the TCI and ending at the P/U coils...

[Larrym]

I took the cover off last night and looked at the wires gave them a stretch and they seemed fine.

Umm....but did you do this whilst the engine wuz running? (O_o)

I do this while running but alls the poking/pulling ain't done wit my fingers. I use a crochet hook fOaR safety. (^_^)

Working theory is that iffin' the wire strands are making/breaking contact INSIDE the insulation where's you can't see? (O_o)

Yoinking the wires this way and that will cause the two cylinders affected by that wire to drop out/drop in. (O_O)

Suggestion- RETEST whilst RUNNING....... and do it CAREFULLY whilst the "questionable" Pod filters are removed. (_Oo)

AND iffin there's a hard failure of either ignition coil, P/U coil (or wires...)? (O_o)

RUN it and spray the exhaust pipes. If it's the left side coil then #1+#4 will be COLD. Right side coil then #2+#3 will be cold. AND on the opposite coils/cylinders that be working right they'll be Hot....EXTRA hot. （´＿｀）




Can you guy tell me which of the P/U wires runs the coil on the left side (the one that runs the 2 outside cylinders) of the bike?

NO! Not gonna do it. (￣ー￣)

1. Pulling the spark plug wires whilst the engine is running is a no-no. Aside from the likelihood of getting shocked and the corresponding warm/wet spot in yur underwear? (THAT'll learn ya....) These coils fire 2 (two) spark plugs at the same time so's you risk damaging the coil itself by pulling off even ONE of the high voltage leads while running. (︶︹︺)

2. Both P/U coils wire(s) is just as ANCIENT and been pulled/stretched equally. Do BOTH iffin' yur gonna have to replace even just one. (◕︿◕)



I was going to chase the wire up from the P/U coil to the main coil. I am thinking it is a wire problem to the coil or the main coil itself. This weekend I am also going to take the main coil off and check it as well. I do have a manual and will check the ohms on both sides.

That's gonna be fun. (^_^)

While yur at it this is a good time to twist/unscrew the spark plug caps from the high tension leads and get rid of any green CORROSION in the side that hooks to the high tension leads. ( ‾́ ◡ ‾́ )

(AND make sure they's actually screwed in all the ways which was the ONLY problem my special had when I bought it and the 3 owners befoaR me COULDN'T find/fix....)

Be warned... MOST folks at this point report back with Ohms readings within the repair manual's specs but they STILL get fixated on one or more of the ignition coils as the PROBLEM. They just don't trust a passive resistance check per the repair manual and even try dynamic function tests like pulling the plugs, laying them on the motor, cranking the engine, and looking fOaR sparks. (ಠ_ಠ)

DON'T!!! (⩺_⩹)

Iffin in yur case where you are accusing the left coil (1+4) of being the criminal? (O_o)

Swap the spark plug wires from 1+4 to 2+3 AND swap the Orange wire with the Gray/White wire. (Keeping the red/white wires where they originally are...) (^_^)

If you CAN (depending on the wire lengths and possibly unbolting the coil from the frame...) swap the 2+3 plug wires to 1+4. Otherwise just leave the gray/white wires unconnected but safely covered wit' electrical tape.

Iffin the SUSPECT coil is trully borked then the problem will X-fer as in 1+4 will now get hot and 2+3 will be cold. ヽ(゜～゜o)ノ

There's ways to test each ignition coil on the bench wit a battery, alligator clips, and using screwdrivers as the switch held up like you's holding a CROSS fending off a vampire but we're not there yet. ┐(‘～`)┌

[shopteach]

I took the cover off last night and looked at the wires gave them a stretch and they seemed fine. Can you guy tell me which of the P/U wires runs the coil on the left side (the one that runs the 2 outside cylinders) of the bike? There are 2 wires at the front top and 2 at the bottom rear of the P/U coil. I was going to chase the wire up from the P/U coil to the main coil. I am thinking it is a wire problem to the coil or the main coil itself. This weekend I am also going to take the main coil off and check it as well. I do have a manual and will check the ohms on both sides.

Awesome info on the air filters. When I get the bike running on all cylinders I will take it for a short ride without the filters on. I will either buy those filters or use one of the fixes you guys suggested.

Thanks a ton guys, I will report back after the weekend or sooner.

[LAB3]

I've seen videos of people modifying the cheap pods by taking a Stanley knife or similar sharp instrument and cutting away the lip on the filter to keep it from blocking those small ports, might be worth trying!

[DEEBS11]

No block design.

[DEEBS11]

Note: You may want black filters instead of red. These also do not block the air holes.

[bikerphil]

Some of us make velocity stacks out of the old air box inlet tubes in order to use the cheap pod filters. No blockage that way.

[DEEBS11]

Do you guys have suggestions as to what and where to get the correct pod filters?

Before you buy filters please try to remove your filters and take the bike for a short ride.

[DEEBS11]

https://www.ebay.com/itm/182441474639