Intro and Problems Running

[Laptop_geek]

First off, HEY!

I bought a 1979 XS1100 Standard a few weeks back from a guy in Arkansas (right outside of Memphis, TN). He had it listed on craigslist for $300 for several weeks and wasn't selling it. I called him up and went to go look at it. When I got there it was in a VERY sketchy neighborhood. Pretty sure 3 or 4 drug deals went down in the house across the street in the 45min we were there. When I got out I just wanted to go look at it quick and get out of there before I was caught in cross fire, but I started looking at it and it looked like it was in pretty good shape, the PO looked like he took care of it and did regular maintenance. He said he stopped ridding it about a year ago. The story he told was the starter button broke (the little plastic button) so he put in push button to start it with. Some where along the line it fried the wiring to the fuse block and he stopped riding it. He started to fix the wiring (took out the old fuse box anyway) and said it was too much for him to play with and was now selling it. There was an old fuse wrapped aluminum fold in the place for the spare fuse so I'm thinking that maybe he had that in several other fuses and that is what cause the wiring to fry. Anyway...I told him I'd take a shot at it and see what I could do, he gave me four other racks of carbs, another starter (not sure if its new or not), Four rebuild kits for 79 carbs, an extra tank for a special(rusty holes for the petcock but clean inside), some misc parts for the carbs, the standard seat (I think its for a standard anyway), a king and queen seat, a service manual, and bags and a fairing for a special. Not too bad of a deal if you ask me. It does have the tank, carbs, and octopus like a special would. Not sure why he changed them over to that mess as I'd rather have everything from a standard anyway.

First thing I did was order new starter and horn buttons ($12 shipped). Then I took off the carbs and took them inside and cleaned them up over the next few weeks (took so long cause it was during finals). I got a new fuse block and wired that in, and replaced the battery (old one wouldn't even think about taking a charge).

Good news is it turned over as soon as I hit the switch, all four plugs have spark, and the oil pressure is building fine. Also the coil pick up wires seem to be new, everything looked really clean down there and they didn't seem to stretch when I pulled on them.

Bad news is it wont run. It will fire on one or two of the cylinders, but thats it. I had it studdering under its own power for a second but thats it. The only way I could get it to do anything is leave the throttle closed and open the enrichment valve half way. Most of the time it will only hit two or three times then not do anything. I've taken off the carbs and re taken them apart, checked the float levels, taken off the octopus and replaced it with fuel lines running straight to the carbs and plugged the vacuum port on the carbs to get rid of that problem.

Here are my thoughts. Because it is only firing with the throttle closed and the choke half way open that would tell me it is running lean. I have the stock air filter and snorkel as well as the stock exhaust on it. I did take out the idle mixture screw, but reset it to 1.25 turns out when I put it back together. All the carbs have the float heights set to the standards in the clymer manual as previously stated.

Question is this: Am I correct in thinking it is not getting enough gas and that is why it is not running? Would something else simple cause this? Because it was running when he fried the wiring (or so I'm told) I am assuming it is in time enough that it would fire and run some what. Could there be something I am missing when I cleaned the carbs? One other thing to note, I have yet to completely clean the tank out (it has some rust as well as varnish in it, but fuel still flows freely), I was hoping to get it running before I spent alot of time and money on fixing it up nice. Could the petcocks be clogged enough so that it wouldn't flow enough gas or is that not probable at an idle? Any ideas on why it wouldn't be running? Most help is appreciated.


PS: I've been reading these forums non-stop for the past month or so trying to learn what makes these bikes tick and so forth and have gone back and read most of the posts in the repair, maintenance, and modification sections. Lots of good info on there.

Below are pictures of the bike.


This is how I bought it.



What a mess



That was easily fixed...



Pretty sure these aren't the stock carbs.

Here is a link to the rest of the pictures.

https://picasaweb.google.com/mustang...eat=directlink

EDIT: Sorry, I didn't realize this was such a long post...

[crazy steve]

Well, from looking at the pics, hard saying what you've got for carbs on that. The pic of the 'box-o-carbs' show a couple of types that aren't for a XS11.

First, those aren't original carbs; those are '80-81 types. Both types have that 'angle iron' brace on the bottom, but only the late type have the upper brace. And they're quite different internally, even if superficially they look the same. If parts have been mixed/matched between types, that can cause all sorts of problems. These carbs are also notorious for clogging easily; if you haven't pulled all the jets out and cleaned everything until it's spotless, you can expect issues. On the '80-81 carbs, replace the o-ring around the float needle seat as that's a known trouble point.

You can run different year carbs on any motor, but you have to jet the carbs according to the year of the carb, not the motor. Make sure all the jets match. Check to see which needles you have, and use the right main jets to match; 110 if they're out of a special, 120 if a standard.

Also clear out that foam over the intake bells in the filter housing... I don't know what's going on there, but that's not right. You may need to buy the correct filter.

Good luck! And congrats on a pretty good looking Xs for $300..

[XS1100_OEM4ME]

Lean or elect

What you discribe is either a lean or elect. problem. Don't know how well you did the carbs, did you remove and clean the emulsion tubes? all jets and ports in the carb bodies clean and clear. The carbs seem to be the hardest thing to get right on these (I know, 30+ years of mechanical experance, and I still needed to lean alot to get mine right) But, as you have said, the elec system was fried, I would start there, check your timming and your pick up coil wires, if all good, check your coils and all grounds. What caused it to melt down, something had to short or cross wires some where Do you have a new battery, or just trying to jump it from something The fact that it will run at all is a good thing, sounds like the motor is sound. The crap in the tank, even if you rebuilt the carbs then hooked them up to a rusty varnished fuel supply, they could need rebuilt again right after start up, very small fuel flow ports / jets on these

[crazy steve]

..The pic of the 'box-o-carbs' show a couple of types that aren't for a XS11.

Looking harder at that pic, it appears that the sets in the upper left and lower right corners of the box are correct '78-79 carbs, so you might want to drag those out and take a good look at them....

The ones that are loose on top are for a twin of some sort and won't be usable, probably even for parts other than screws...

[XS1100_OEM4ME]

Wow!

Wow, I think with the help of the smarter guys then me on here, you will get that very nice bike up and running But any way you look at it, the parts alone are worth 5 times what you paid for the whole lot Good find, and good luck with your bike, love to see more pic's as you go

[ViperRon]

simple tests

Not sure what tools you have to work with but have a few simple sugestions to make sure you go in the right direction. First remove all four plugs and do a simple compression test. IF you do not have a compression guage you can go to most advance auto stores and put a deposite on one and use it for free. You can also fit a finger tight over each spark plug hole and cranking the bike feel for pressure. It should blow your finger off the hole. If you have small fingers do not put them in the holes. Even if the pressure is low like 80 lbs the bike can run. If you do not have good compression you can squirt a small amount ( less than half a teaspoon please ) of heavy oil into the cylinder and compression will increase if its rings. If not then you can have a valve or timming problem. Valve problems can be as simple as sticking valves or carbon deposites expecially if the bike has been sitting. If compression is there make sure the plug holders are tight and put one plug at a time in find a good ground on the cylinder head and in a very dim lit area see if you have spark from the plugs. With the plugs out the bike should crank quickly and you should be able to see a good blue spark. You can also get a tool to test for spark. If you do have spark check the wiring to make sure that the wiring to the plugs are correct and not swapped. This simple amount of testing can give you some confidence that fuel is your problem. These bikes are notorious for bad wiring connections and damage by previous owners. In the troubleshooting and maintenance facts here on the site there are step by step electronic troubleshooting tips. No matter how much fuel if the compression is bad or no spark it will not run. When faced with a problem I try to identify tests to ensure I am headed in the correct direction. I would not want you to spend days going over and over the carbs and find the problem is elsewhere. Hope this helps.

[Lonerider62]

Welcome to the best info on the XS1100 you'll find at your fingertips. Now, ViperRon had some good advice about checking your compression which may be an indication there are problems you're not ready to screw around with (like zero comoression in any cylinder). You said you had spark in all four holes but that doesn't mean you necessarily have spark uder compression if you were checking with the plugs ouside the engine like most of us do. Even the PO's who think they are telling the truth usually are confused about the facts themselves so don't take everything the PO said as the gospel truth. That, you have to determine for yourself. You've already been reading the forum so you are a step or two ahead of most newbies and the journey towards a good running bike has just started. IMO, if you want a bike you can trust to get you to the store and back, you have to check everything, and I mean everything. You will more than likely have to get the carb issue eliminated by either just totally swapping out the bank of four after giving them a REAL GOOD cleaning or just redoing the ones already on the bike. If the tank is rusty, you have to correct that with Kreen or whatever method you want to use. Not much use in pouring more foul fuel into a bunch of clean carbs. You'll also have to eventually check cam timing, valve cleanance, etc,etc. Take it one step at a time and as you go, you'll eliminate each possible problem. Good luck, ask as many questions as you have when they come up.

[James England]

Look at it this way. The firing cycle is 'suck, squeeze, bang, blow'. ie fuel/air in from the carbs, compression from the piston, spark to ignite the fuel/air mixture and then exhaust. In order for the bike to run, you have to get all these elements correct.... the correct mixture of air and fuel, a spark at the right time, valves working correctly to allow the mixture in and the exhaust gases out.

There are some very simple and free tests to check the basics. Remove all the plugs and turn the engine with the starter whilst pressing your finger hard on each plughole in turn. You should feel compression and hear a pronounced hiss when the piston is on the compression cycle. A compression tester will give you a reading but the finger test is enough to establish that there is compression and no holes in the piston or stuck valves etc. You can get sidetracked on compression readings if you use a gauge.... I don't even know what mine are and don't care... the bike starts and runs perfectly.... that's enough.

Next, as you appear to have done already, check that there is a spark at each spark plug by grounding the plug on the head (connected up to the HT lead of course). You can check the spark timing approximately by doing the compression finger test and grounding the plug nearby. You should get pressure on your finger, a hiss and then, almost immediately, a spark at the plug. These bikes have a 'wasted spark', so you'll find you get a spark on another plug (when the relevant piston on on the 'blow' exhaust cycle). The main thing is that there should be a spark when the finger test shows compression and hiss.

Right, so hopefully you now have sparks on all plugs, at the right time and compression on all cylinders. So you've verified the easy squeeze & bang side of things enough to rule out disastrous mechanical problems or disconnected ignition wires etc.

So, you're left with the 'suck' side of things and this can be more complicated. Each piston sucks fuel through the carb. If there any leaks at the manifolds, then it will suck air in and the mixture will be wrong. Check the manifolds visually for cracks all the way through. The manifolds are double skinned and the outers are often cracked but not leaking. Sometimes they are leaking though. I'd take them off and have look inside them. If they are smooth, then that's fine.

Next is the carbs. They will be full of filth, fine rust possibly etc etc. There is a division of thought on this forum re rebuild kits. Many people advise not using them but I used 4 sets and had absolutely no problems whatsoever. You can clean the originals though and many people prefer this. Each carb has a rubbery diaphragm which pulls up the throttle slide when the throttle is twisted. It does this in reaction to a partial vacuum acting on the diaphragm. These are usually old, perished, with pinholes or cracks and they need to be replaced in any carb rebuild/cleaning. On your carb rebuild, the object of the exercise is to get the insides of the carbs scrupulously clean, all the jets clean, the float valve needles should work correctly and the floats be not leaking. These bits are what maintain the correct level of fuel in the float bowl. If the floats levels are wrong, then the fuel will be wrong. Everything has to be just right in order to work. This forum has many threads re rebuild, float levels etc...

[TopCatGr58]

Hey there Laptop Geek,

First of all, lots of great advice and troubleshooting tips already given.

One of the tips not specifically mentioned is to ensure that the small pressed in jets in the float bowls are flowing freely and not clogged. They feed the Enrichment circuit which enables being able to start when cold, but if clogged= no gas, no start!

Secondly, hopefully you didn't soak the entire carb bodies in harsh carb cleaner, that would have damaged the butterfly shaft seals, causing severe vacuum leaks, which would also cause problems with the engine not being able to suck in fuel from the carbs due to excessive air leaks, so only sucking air and not fuel.

Putting some inline fuel filters would be a prudent thing until you get a chance to clean out the tank a bit, but keep them even after you get it cleaned/derusted!

You'll want to check fuel flow to make sure the carbs are getting fed. The Special petcocks are just gravity feed, the OCTY is the vacuum control valve, but can be bypassed by just using the PRIME position on the petcocks. Other impediments to fuel flow can even be the "T" fittings between the carbs...can corrode and get gummed/varnished up. Also a screen under the float needle seat can clog.

As stated, you have spark, but after cranking and cranking, etc. a new battery can get run down, not to mention the old wiring can cause a drain/resistance to the voltage to the ignition coils or TCI, if drops to 10.5 volts, TCI won't work. The 79 uses a ballast resistor to power the coils once the engine is running, but is bypassed during starting. If it's damaged, cracked, etc. and not flowing electricity, then the bike can act like it will start while the starter button is engaged, but won't provide spark when released, so can't keep running.

I can't tell from the limited views of the carbs what year/model they are? As Steve said, any carbs, but jet according to carb style/year.

Good luck with the diagnostics and hope you get to hear it roar real soon!

T.C.

[jetmechmarty]

You cleaned the carbs and that's good. Then you put fresh gasoline in a tank full of rust and varnish. Your carburetors are not clean anymore. They're full of crud. You have to do that job over, and run on a CLEAN fuel source.

[XS1100_OEM4ME]

Rust

+1, not trying to beat a dead horse to death, but it is what it is

"The crap in the tank, even if you rebuilt the carbs then hooked them up to a rusty varnished fuel supply, they could need rebuilt again right after start up, very small fuel flow ports / jets on these"

You cleaned the carbs and that's good. Then you put fresh gasoline in a tank full of rust and varnish. Your carburetors are not clean anymore. They're full of crud. You have to do that job over, and run on a CLEAN fuel source.

[Laptop_geek]

Ok guys, Finally getting around to replying.

As far as capabilities go, I am a mechanical engineering student and my brother is a fabricator. I have or can get access to most any common tool that is needed for working on motorcycles.

Yes, the tank and carbs are both from a special (later model I'm assuming). I have another rack of the same carbs and two racks of the earlier carbs. I'm going to clean/rebuild the earlier carbs cause I have the kits for them. I might also take and paint/polish them to make them look good.

I am looking for a standard tank with the petcocks to replace the special tank, I realize it might clog up the carbs, but the couple of times I've pulled off the carbs and taken them apart they have all been clean and clear, so I'm not too worried about that, I will take TC's advice and add some inline filters.

I've got a maintainer on the battery that stays on it while I'm working on it. I try not to crank it over too much at one time, gives me time to think about whats going on with it and try any fix it.

I tried the trick with the oil in the cylinders, it didn't change anything. I also put my finger over the spark plug hole and checked the compression and timing. Everything looks like its in order there. The rubber intake manifolds were replaced by the PO and look like there new.

The carburetors were cleaned by disassembling then cleaning them. Each piece was taken out, cleaned, and put into the same carb it came out of. I'll take it apart again and make sure all the jets and needles match the carbs.

The 79 uses a ballast resistor to power the coils once the engine is running, but is bypassed during starting. If it's damaged, cracked, etc. and not flowing electricity, then the bike can act like it will start while the starter button is engaged, but won't provide spark when released, so can't keep running.

That is the kind of info that I need. I understand the basics (and the not so basics) of an internal combustion engine and the basics of the carburetors, its the little things like that which help me.

[Laptop_geek]

I took out the oxty and put a fuel line running down from each petcock to the carb set on that side. Nothing changed.

Does the resistor that powers the coils commonly fail?

[crazy steve]

Does the resistor that powers the coils commonly fail?

Generally, no. But they have been known to once in a while. Try bypassing it; just plug the two wires that go to it together and if the bike then fires, that's likely the problem. Don't run it like that for more than a minute though, as the additional current draw will toast your ignition box.

[XS1100_OEM4ME]

Capabilities

We are not doubting your capabilities. Many on here have vast mechanical experance but you will find your XS can be a fickel b!tc# at times The carbs can be very troublesome (did mine 5 time before I got them perfect, and that is with 40 years of mechanical experance) The electrical system can have hard to find gremlins also, we all just try to help if a fellow XS member ask, good luck with your bike

Ok guys, Finally getting around to replying.

As far as capabilities go, I am a mechanical engineering student and my brother is a fabricator. I have or can get access to most any common tool that is needed for working on motorcycles.

Yes, the tank and carbs are both from a special (later model I'm assuming). I have another rack of the same carbs and two racks of the earlier carbs. I'm going to clean/rebuild the earlier carbs cause I have the kits for them. I might also take and paint/polish them to make them look good.

I am looking for a standard tank with the petcocks to replace the special tank, I realize it might clog up the carbs, but the couple of times I've pulled off the carbs and taken them apart they have all been clean and clear, so I'm not too worried about that, I will take TC's advice and add some inline filters.

I've got a maintainer on the battery that stays on it while I'm working on it. I try not to crank it over too much at one time, gives me time to think about whats going on with it and try any fix it.

I tried the trick with the oil in the cylinders, it didn't change anything. I also put my finger over the spark plug hole and checked the compression and timing. Everything looks like its in order there. The rubber intake manifolds were replaced by the PO and look like there new.

The carburetors were cleaned by disassembling then cleaning them. Each piece was taken out, cleaned, and put into the same carb it came out of. I'll take it apart again and make sure all the jets and needles match the carbs.



That is the kind of info that I need. I understand the basics (and the not so basics) of an internal combustion engine and the basics of the carburetors, its the little things like that which help me.