Possible fuel line issue?

[shopteach]

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.

[JeffH]

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.

It would be HELPFUL if you could provide some detail on "Still isn't running right".

Start OK? Idle OK? Takes throttle OK? Revs up OK? All 4 pipes heat up equally?

What about the Vacuum ports? They capped or open?

A bit more detail would be helpful to get started. If pooping out on the highway it could be Tank Venting but if it barely runs that wouldn't do it.

Jeff

[DEEBS11]

So many modifications. So many opportunities for issues. Could be carb problems (most likely). Could be ignition. Could be off a tooth on a cam. Who knows. Is that gas cap vented? Does gas flow freely from the petcock?

[bikerphil]

Running single fuel tap should not be a problem, I run both my XS11's like that.

[DEEBS11]

Yes, me too.

[cajun31]

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.

I typically don't get too involved with modified bikes. As Deebs stated so many modifications it is very hard to give creditable advice. Just looking at what you have it raises a few questions. Once of which Deebs pointed out. Is the gas cap vented? You have the original carbs on the bike so the second question is they vent to the atmosphere so am assuming you know that but where are the vent lines routing too? You are running pods. Are they blocking the air intakes on the backside of the carbs. Many do. You mentioned you got a jet kit. What exactly was included and assuming they accounted for all the mods when selecting the jet sizes. Last but not least you are running straight pipes. Are they baffled or open. These bikes from the factory with stock pipes were balanced. Meaning the backflow had a lot to do with how they run. Minus that can cause issues and jetting change requirements. We need to know more in order to help.

[Larrym]

Iffin the bike runs like THIS at idle and it's spitting, popping, and SNEEZING? (O_o)

Then go HERE and read this-

https://xs11.club/forum/idle-talk-forum/xs11-xj11-discussion/884261-idle-circuit-running-lean-after-mods-need-advice?p=884277#post884277

a Vid showing just wut yur bike runs like would be a good startin' point. ( •_•)

[shopteach]

Part of the problem is it has run well, and then it won't.

Starts ok. Idles pretty good. Then it doesn't take throttle well and won't rev well. Seems like pipes are heating up pretty similar. I can do a better check on that.
Vacuum ports have caps on them. I have tried running it with the gas off and doesn't seem to change anything so I don't think its that.

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. Pipes are straight with no baffling. I told Sigma that when they sent the jet kit.

Again runs good sometimes, not sure why. Here is a video of it running great. I tried to go out a week later could get out of its own way. Sorry, I don't have a video of it running crappy. I have no idea what is the difference in it running well and then poorly.

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



https://youtube.com/shorts/mTmdooZ6JVU?feature=share

[Larrym]

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)

[DEEBS11]

Part of the problem is it has run well, and then it won't.

Starts ok. Idles pretty good. Then it doesn't take throttle well and won't rev well. Seems like pipes are heating up pretty similar. I can do a better check on that.
Vacuum ports have caps on them. I have tried running it with the gas off and doesn't seem to change anything so I don't think its that.

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. Pipes are straight with no baffling. I told Sigma that when they sent the jet kit.

Again runs good sometimes, not sure why. Here is a video of it running great. I tried to go out a week later could get out of its own way. Sorry, I don't have a video of it running crappy. I have no idea what is the difference in it running well and then poorly.

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

https://youtube.com/shorts/mTmdooZ6JVU?feature=share

This possibly sounds like classic vapor lock perhaps caused by that suspicious looking gas cap. Try (carefully) riding it around without the cap installed. If it runs well, you have a simple gas cap issue.

Also, those filters look like "blocking" cheap Chinese filters. Take them off and try riding around without them for a test.

[shopteach]

I am going to try the choke trick tonight. I will report back on what I find out. If that doesn't work, Ill figure something out for the cap scenario. Thank you guys for the help so far.

[Larrym]

Fingers crossed fOaR you on the test ride as in the choke usage wuz the one/only issue. ┐(°,ʖ°)┌

Part of the problem is it has run well, and then it won't.
Again runs good sometimes, not sure why. ....../...... I have no idea what is the difference in it running well and then poorly.

Iffin' during the test ride the bike bounces back-n-forth between running great and then running like the prior mentioned Ford Pinto? (O_o)

<SPOILER ALERT>

Common point of failure is the P/U coil wires. (^_^)

We'll cross that bridge iffin' we come to that. (_Oo)

[shopteach]

Well tried to test the choke full on. Didn't want to run. I had to go about half throttle just to get it going and ran very poorly. It sounded like it wasn't running on all cyinders. Every once in a while it seemed to try and fire on another cylinder. I finally desided to pull a plug wire to see if I could figure out which cylinder wasn't running right. When I pulled either of the two outside cylinder plug wires nothing happened. When I pulled either of the two inside cylinders there was a drastic change.

Sooooo, tell me more about this P/U wire? And how do I check to see if it's that or the coil itself? Where do I go from here?

I do feel like we are getting somewhere finally. I have been spinning my wheels on this for a while.

[DiverRay]

Pickup coil wires usually break at the clamp under the left cover. Yamaha had the clamp way too tight since day one. I know, as I had a dealer send in something to them in 1978 when I had my first XS1100. Here is the repair posting: https://xs11.club/forum/repairs/batt...il-wire-repair

[DEEBS11]

Air filters.