misfire

[ridingagn]

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.

Yep, good strong spark. when jumped from cap to installed plug the spark is bright blue and will arc about 1/4"
Martin

[ridingagn]

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

Nope Tod, the octo is long gone. Genius and his brother are pertty smaer all right. They let dad figure it out. Meant to pull the carbs today, but got too busy.
Martin

[WMarshy]

JAT...No one asked so I though I would. Do you have inline fuel filters? Might be a glob-o-gunk came lose from that good'ol seamfoam, coulda made a mess in the jet...? It seems like one of the changes you made when the problem came about. GL

[ridingagn]

JAT...No one asked so I though I would. Do you have inline fuel filters? Might be a glob-o-gunk makin problems in a jet...?

No. He's running on the tank valve screens. They had good solid flow, and they have been removed and cleaned anyway.
Martin

[ridingagn]

You could be right, I was maybe misreading the



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

Yes.... it runs badly all the time, like on 3 cylinders. And as it's sitting there running rough, it puffs. When given throttle it puffs and farts. Pretty talented for a bike.....
Martin

[trbig]

I'm still thinking that it's getting flooded, which would be float/float valve. If it's not leaking any gas out of the carbs, keep a really good eye on the oil level since it may be running into the crankcase by the rings. This will ruin the bearings in a hurry.


Tod

[newc4]

Pilot jet

My money is on the pilot jet. Cool pipe, rough idle.

Darrell

[ridingagn]

My money is on the pilot jet. Cool pipe, rough idle.

Darrell

I should start a solution pool. Lets see.......
100 squares, $100 per square....... 50% fee = nice new bike.....
But not so much fun to work on.

Now..... if I can get the pilot jets out.....
Martin

[trbig]

If the pilot jets are all there and tight, I don't think you should have to mess with them.


Tod

[ridingagn]

If the pilot jets are all there and tight, I don't think you should have to mess with them.


Tod

Okay..... today I removed the carb bank. All jets were in place, all passages and orafices were clear and totally unobstructed. All needle valves were in perfect shape. Screens on float needle valves were all crystal clear, as were the tank valve screens. The inside of the carbs basically looked clean as a whistle. All floats are neoprene and measured 23.5mm as measured per page 254 in Clymer manual. The choke dentents work properly and all parts are tight, clean and function normally. So I think I have ruled out the carbs. However for kicks I moved the #4 float to #3 carb.

Just for grins I removed the intake manifolds. There were no gaskets, and on #4 there was WD40 between the manifold and the head. I suspect I was getting air between the manifold and the head. I made a set of "phonebook" gaskets and re-mounted the manifolds.

Well....... I am firing on all four now. Header temp is pretty even across all four cylinders and the idle is smooth. I had to re-sync because the apparent air leak on #4 was affecting balance. But...... I still have a problem.

The puff back has moved to #3 cylinder.
That means the puff problem followed the float, but not the cold header temp or the rough idle.???? @#$%*&.

Also, after 1/2 mile or so, it starves out, and will die. Choking will get it running again, then runs fine without choke for another 1/2 mile then repeats. Sounds like a vacuum valve issue (octo has been removed) and I will track that down.


So for those of you who like a challenge.....
why would the puff follow the float? (remember it runs super smooth and at proper temp otherwise)
Thanks by the way, for everyones input. You guys are masters.
Martin

[ridingagn]

If the pilot jets are all there and tight, I don't think you should have to mess with them.


Tod

Something I noticed was that the idle mixture screws are all across the board.

Cyl Turns out
#1 3
#2 4.25
#3 4.75
#4 2.5

Clymar says to not adjust these, but if you have to, set them at 1.25 out as an initial setting. What's the best way to get these at their optimum setting?
Martin

[Rasputin]

I like to use a colortune. Works well for me. This thread will show you how if you do not have a colortune
http://www.xs11.com/forum/showthread.php?t=13124

[XSokieSPECIAL]

Also, after 1/2 mile or so, it starves out, and will die. Choking will get it running again, then runs fine without choke for another 1/2 mile then repeats. Sounds like a vacuum valve issue (octo has been removed) and I will track that down.


Martin

Check the vent in the fuel cap. If you can, open the cap a little when it dies out and see if it picks back up.

[ridingagn]

I like to use a colortune. Works well for me. This thread will show you how if you do not have a colortune
http://www.xs11.com/forum/showthread.php?t=13124

Great write up !! Thanks
I followed it to the letter. That did make a good difference. The idle remains perfect. Everything synced and no puffs, farts or rough running. Until I give it a little gas. As soon as I gently throttle and hold it to around 1500rpm I start to get pops out the exhaust. Not consistant, but 3 or 4 every 5 seconds or so. This continues all the way up through the rpm's. Go back to idle and it's perfect. No hanging idle or dropping idle, so I think the idle mix and sync are right on. Checked for exhaust leaks...... all seems ok. Hard to tell which cyl since it's a 4 into 1 pipe. No puffs out the carbs at all..... just farts. And now it's hard to start. Have to give it throttle and turn it over 5 or 6 times before it starts. Then it idles fine.

Am I chasing my tail? I have a spare carb bank. They are an older set with the big idle mix screws on the top (no plugs). I am tempted to clean them up and mount them. See what happens, although I feel like its electrical now.
Martin

[XSokieSPECIAL]

Great write up !! Thanks
I followed it to the letter. That did make a good difference. The idle remains perfect. Everything synced and no puffs, farts or rough running. Until I give it a little gas. As soon as I gently throttle and hold it to around 1500rpm I start to get pops out the exhaust. Not consistant, but 3 or 4 every 5 seconds or so. This continues all the way up through the rpm's. Go back to idle and it's perfect. No hanging idle or dropping idle, so I think the idle mix and sync are right on. Checked for exhaust leaks...... all seems ok. Hard to tell which cyl since it's a 4 into 1 pipe. No puffs out the carbs at all..... just farts. And now it's hard to start. Have to give it throttle and turn it over 5 or 6 times before it starts. Then it idles fine.

Am I chasing my tail? I have a spare carb bank. They are an older set with the big idle mix screws on the top (no plugs). I am tempted to clean them up and mount them. See what happens, although I feel like its electrical now.
Martin

JAT---- picup coil wires? This drove me nearly insane (a short drive) when I got my XS.

It did nearly the same thing.

And later on after I had repaired them, I was having an intermittent problem on acceleration because of a P/U wire that had rubbed through the insulation and was grounding out on a screw head when the vacuum advance pulled the breaker plate back.