misfire

[XSokieSPECIAL]

This will also show up on a compression test as a low cyl.
worth every penny?

[QUOTE=geniusloerts; even the compression is good its higher than all the rest..... QUOTE]

Hate to argue with a moderator but-----------------

[DiverRay]

OK, so don't!! We can't read and retain EVERYTHING! We try, but a lot of us on this board are trying......
I still think he may have a problem with the valves. IF it's higher, it may have a carbon buildup that is part of the problem!
Like everyone else here, I'm just trying to think things out.........

[XSokieSPECIAL]

OK, so don't!! We can't read and retain EVERYTHING! We try, but a lot of us on this board are trying......
I still think he may have a problem with the valves. IF it's higher, it may have a carbon buildup that is part of the problem!
Like everyone else here, I'm just trying to think things out.........

Ok Ray--- relax --- take a deeeep breath. Got one of those oxygen tanks handy?

EASY----EASY.

Just bringing that to your attention.

[ridingagn]

OK, since no one wants to try something else, it's my turn!
Check the valve clearance and timing chain tension. The valves on the XS1100 CLOSE after a while. You may not have the valve fully closed, so it can't fire properly. This will also show up on a compression test as a low cyl.
Again, we don't have all the facts, how many miles since the last valve check, etc.
Just my $0.02, and worth every penny!

Chain tension adjusted per spec. Valves checked 100 miles ago during engine out 2nd gear repair. Compression checks at 120#. 145# with oil in cyl. to eliminate bad valve possibility.
Papaloerts

[DGXSER]

You know, I had one cylinder that ran really rich right after I cleaned my carbs. I tried all the tricks to isolate it. tried changing mixture screw by as much as two turns and no change. Tried changing plug wires around, problem stayed on no 1 cylinder.

Anyway, in the end, when cleaning the carbs I had pulled out the needle valve and then reassmebled it in the wrong order, spring on bottom instead of top, but only on the one cylinder. Fixed that and she runs like a top ever since.

Yeah, not the likely suspect, but a suspect none the less.

[ridingagn]

You know, I had one cylinder that ran really rich right after I cleaned my carbs. I tried all the tricks to isolate it. tried changing mixture screw by as much as two turns and no change. Tried changing plug wires around, problem stayed on no 1 cylinder.

Anyway, in the end, when cleaning the carbs I had pulled out the needle valve and then reassmebled it in the wrong order, spring on bottom instead of top, but only on the one cylinder. Fixed that and she runs like a top ever since.

Yeah, not the likely suspect, but a suspect none the less.

Hey..... I respect all suggestions. I've been doing this for a while, so I have done a lot of the things suggested, but I do welcome the brainstorming. Sometimes another perspective on something I may have tried will be the answer. The bike has run fantastic up till a few days ago. Nothing happened, nothing was done or adjusted. It just all of a sudden, in the middle of a tank of gas during a 40 mile ride, started to run rough and here we are.
Please keep the ideas coming. I appreciate them all.
Papaloerts

By the way...... I'm Geniusloerts and Cloerts' (on this forum) Dad. I do the re-build and restore work on my son's xs11's along with them in my shop. Have my own xvs1100, xvs1300 and a shop full of my son's xs11's at the moment.
Happy to meet you all.

[DGXSER]

OK so you switched plug wires and tested temps and the misfire stays with no 4 cylinder correct? You have good compression and valve clearances on no 4 correct? The only thing left is carburationm but it is really rare for carburation to go south like that so instantly.

Have you swapped the actual plugs around to see if that changes it?

[ridingagn]

OK so you switched plug wires and tested temps and the misfire stays with no 4 cylinder correct? You have good compression and valve clearances on no 4 correct? The only thing left is carburationm but it is really rare for carburation to go south like that so instantly.

Have you swapped the actual plugs around to see if that changes it?

I agree...... the problem acts electrical, but diagnosis is pointing to carb#4 float.
I methodically swapped the plugs and wires and caps.
Did not follow plug, did not follow wire, did not follow cap.
Swapped out coil with a within-spec 1/4 stock coil. No change.
Used spark indicator tool on all 4 cyl's and the spark is same color / intensity on all 4. Spark on cyl 4 is strong and blue and steady when 5th pulg is grounded to engine case. Only indication there is a problem is rough running, puff back through carb and low temp on header pipe.
Will pull carb bank in morning.
Martin

[XSokieSPECIAL]

it really sounds like a fuel problem to me from what I have heard here.

if you have a spray can of carb cleaner or brake cleaner try spraying a little in the vacuum port on the boot of that cyl while it's idling and see if that makes any difference.

[Rasputin]

I had a somewhat similar experience when a jet I had installed backed out. It affected only the one cylinder. I somehow had not tightened the jet in its place correctly. It ran fine for a while and all of a sudden it started acting like what you are describing. It had backed itself almost completely out. JAT

[DGXSER]

If you have a colortune as it sounds, what did the flame look like in no 4 when you put the plug in there? Sounds like your saying you have good spark on no 4 when grounded with another plug. Could still be a break in a plug wire, only shows when twisted just the way it is when installed?? (yeah reaching a bit again.)

Can't hurt to pull the carbs and have a look.

[trbig]

It just sounds like the float valve got some crud in it and it's not letting the needle seat. If the carbs have brass floats, they do on a rare occasion develop pinholes, but it's not a common thing. If they are neoprene, you can rule that out.

I also had a pilot jet come out and it ran terrible.. but it ran terrible all the time, not just occasionally. By swapping the wires and it still ran bad on that cylinder but #1 still ran good, I'd rule the electrical out for now and concentrate on the carb. OR... make one of the geniuses concentrate on his carb! lol.

You never did say... Does the bike have an octopus on the carbs?


Tod

[Rasputin]

The bike has run fantastic up till a few days ago. Nothing happened, nothing was done or adjusted. It just all of a sudden, in the middle of a tank of gas during a 40 mile ride, started to run rough and here we are.

Trbig, not to question your abilities, as I am sure they far surpass mine but I dont read where he says it runs bad occasionally. The sudden loosening of the pilot jet on #4 could result in it running very rich and thus cooler temps on the pipe. I know mine ran like a bag of shat until I found it and tightened it back up.

[trbig]

You could be right, I was maybe misreading the

I still have the random backfire through the carb...


# 4 puffs back through carb randomly at idle, backfires randomly at 3,000 rpm

I guess that doesn't mean it isn't running rough all the time. BUT.. I have lost a pilot jet and the cylinder wouldn't run at all. It was simply too much fuel and not enough air to get a combustion and the pipe was cool to the touch.

It's all a guess until he pulls the carbs.


Tod

[dbeardslee]

Something else to chew on...

# 4 header idles at 105 degrees, #1,2,3 idle in 140 range.

When I check my header pipes using an infrared thermometer I get a reading that usually runs between 220 and 250 degrees F, depending on the ambient temp. I've checked several others using the same method, and this seems to be the normal operating range. If the numbers in the quote are correct (and in Fahrenheit) it seems like they're all running cool. Just throwing it out there.