Low RPM Miss

[Lloydo]

This just started out of nowhere. '79 XS Special, just started kind of missing or sputtering at low rpm, like pulling out from a stop. Misses untill around 3500 rpm, then smooths out & goes like normal. Searched & read a few posts about pick-up coils, clogged jets, etc., don't know where to begin. Just changed plugs, hoping it was that simple, but to no avail. Where should I look first. Thanks.

[FJ111200]

Just changed plugs, hoping it was that simple, but to no avail. Where should I look first.

Air filter or pods.

[motoman]

Air filter or pods.//////makes no difference as he stated it just started doing what it'a doing. Pull left ignition cover off and using BOTH hands pull and try and seperate each of those wires a section at a time. If one is broken internally the sheath will stretch like taffy. If one is found broke, do NOT soldier. /use a SMALL piece of butt connector to re-attatch with a tiny piece of shrink tubing over exposed metal. Those wires have to freely move for advance to work corrctly. Also, while there, make sure the advance assembly rotates FREELY with absolutely no resistance. Let us know what U find.

[FJ111200]

The geezer asked where to look first.
We all know where the next steps are.

[motoman]

The geezer asked where to look first.
We all know where the next steps are.
----------------------- The suggestion was given...........re-read if necessary

[TopCatGr58]

The geezer asked where to look first.
We all know where the next steps are.

Hey FJ,

Lloydo is only 1 year older than I am, and I don't consider myself a "GEEZER", and I'm sure he doesn't either. I don't know how old you are, but seems like you're not old enough to have learned how to post POLITELY!

This is NOT the UK site. You've been warned previously about your posting style. This is your second warning, and yes, it's a PUBLIC one, none of this hiding in private PM's stuff. I am posting this in a manner to provide transparency for all members to see what is being done, said, etc., to maintain proper decorum and order on this site. If you can't participate according to the guidelines,then your privileges will be revoked!

[TopCatGr58]

Hey Lloydo,

As Motoman said, the Pickup coils are a likely culprit, but the carbs are also suspect. A quick test for the coils without actually disassembling much is to take the vac. adv. hose off of the #2 carb, cap the carb port, and then run the bike and see if it still misses. If it doesn't then it's more likely the PU coils/wires since the vac adv isn't rotating the timing plate and the PU coils wires aren't flexing. If it does still miss, then it's now more likely the carbs, the pilot circuit since it comes alive above the 3k rpm range.
T.C.

[b.walker5]

Hey TC, not sure how you view the term Geezer in the States but in the UK, and indeed here, it's not a derogatory expression.

http://en.wikipedia.org/wiki/Geezer

Theres no doubt that poms are different but i'm pretty sure FJ didnt mean anything insulting with his post, or at least that's the way I read it.

[scrapvalue]

Sounds like you have some crap in one or more of the low speed jets.
Sounds like the problem disappears as soon as you get into the high speed side of things.

Had the same symtom on my rejetting project. As soon as I put the bigger pilot jets in, the problem went away.
Not saying you need bigger jets, just that it sounds like something is restricting the flow down low.

[TopCatGr58]

A matter of perspective.

Hey Walker,

Thanks for the link.

Geezer is a term for a man. It can carry either the connotation of age and eccentricity or, in the UK, that of self-education such as craftiness or stylishness.

Hey FJ,

I stand PUBLICLY corrected, and publicly accept the correction and my interpretation error...biased on MY USA perspective and experience with what some man called the difference between the USA and England.....2 countries separated by a "common" language!

I received your email to the Admin contact us link, and will reply there as well, incase you don't come back here to see this "Apology".

Just another example that shows that I'm far from perfect, almost human!

T.C.

[James England]

Searched & read a few posts about pick-up coils, clogged jets, etc.,

Begin here. Sudden misfires which appear out of nowhere don't start with air filtration. More like fuel contamination or electrical problems. The usual culprit is the pickup wires where the timing plate moves or under the bike where they link into the harness. There could be allsorts floating about in the fuel system which have clogged something suddenly. The key thing here is the suddenness of the onset. That is not a symptom of air filtration at all.

[motoman]

The key thing here is the suddenness of the onset. That is not a symptom of air filtration at all.////////Thanks for the +1 James!

[natemoen]

I wild have to agree witj all the possibilities that have been mentioned.

More importantly though, I see you don't live to far away, I think we need to try to get all the local XS's together at some point!

[Lloydo]

Miss at low RPM

Seems to have been carb related. I put a half can of seafoam in a tank of gas two weeks ago today, burned through that & refilled it that day & added another half can of seafoam. I got involved in a bathroom remodel at home & haven't had the bike out since. I thought about it a few days ago & wondered if it just sitting in the garage might not be a bad thing, with the seafoam maybe dissolving the clog. Well, I got it out this morning, & at first the miss was still there. After a few miles, the miss was gone, & now it runs fine again. We put on a good 150 miles today. Thanks all for the suggestions! Again the forum comes through. BTW, no offense taken about the geezer thing!

[fredintoon]

- - - no offense taken about the geezer thing!

Hi Lloydo,
there are advantages to the language difference, you can call TC a wanker because he don't know what it means (TC, it's Britspeak for jerkoff and you ain't one) you can't call him ******* because the bad word auto-sensor spells in US English but we can indeed metaphorically kick his arse.
Likewise, I have given up on explaining to my Canadian wife that while Bitch is an insult, you poor little bitch is an expression of affectionate sympathy.