Spark plug diagnosis

[jack02]

Well I went out for a lengthy spin this morning on my '89. Been laid up for ages so I'm in the process of identifying and eliminating niggles,but the one I encountered wasn't so little. During the course of the ride I became increasingly aware of a general malaise in the motor,which increased proportionally with the revs. Being something of an old hand I figured that it was running a bit lean (bear in mind that I recently fitted a 4-1 exhaust and I've changed nothing). Whipped the plugs out when I got back and according to all the diagnosis charts I can get my hands on,my motor is running absolutely as sweet as can be - I've never seen such a textbook example of how plugs should look in the flesh! No deposits whatsoever and a nice even tan colour,all of them,to the point where you can't tell them apart.
Anyway,I won't get the chance to ride again for a few days,but I did get time to whip the tops off the carbs and drop the needle circlips one groove,thus richening the midrange-on a tad. Any thoughts anyone,and have I opened a can of worms by fiddling with the jet needle position? Gotta go!

[Arnie]

Not in my opinion.  Change anything you want to, one item at a time.  Take notes of what you did when and why.  Then make follow up notes on discernable changes in performance and indicators.
This is the way you learn.
If you have time, report it back to us.  Then we can also learn or argue about it :-)

Cheers,
Arnie

[andyb]

A plug chop vs taking old plugs out?  Not the same thing so much.

Also note that you can't get a decent read on a plug without either a magnifying glass and good lighting or (easier and better) an angle grinder.

[jack02]

Got a little time to go for a spin this morning (UK,6.45am!) and the simple act of dropping the circlip one notch has worked wonders. Loads of instant power that had me backing off the throttle/looking for the next gear,depending on the road situation. Just need to sort out the slipping clutch now,which has suddenly become apparent with the new-found full-blooded power! Still short on time and I've not bothered to check plugs (and tbh I'm now not inclined to),but as a matter of interest where does the angle grinder come in,andy??

[andyb]

Chopping them up so you can read them clearly.  The main/WOT area is down low.  If you "read" this like most folks, you'd think it's either a little lean or ok, but it's actually a touch richer than it needs to be.  Should be a safe tune, though.

[jack02]

Cool! I'd say the colour of my electrodes that I noted the other day (before I raised the needles a notch) was the same as that in your pic immediately above the bright white portion. I finished my night-shift four hours ago and just sat down from getting the nipper off to school etc,so I really can't be ***ed to go get my plugs out to see the difference the raised needles have made to plug state. But..... I did go to work on the bike last night. Took the opportunity to whip out the baffle (yes it's one of those sorts of exhausts) just to see what difference there was in noise  (!). Answer - not a great deal,probably just enough to cause irritation on a long run... I put it back in. Anyways,I happened to notice quite by chance when the light struck it at a certain angle,what appeared to be minute metallic specks on the baffle. Closer inspection revealed an extremely fine,even coating of said particles,which wiped off with one finger-stroke. What is this?? I'm assuming that's what you were getting at/looking for when you mentioned "good lighting/magnifying glass" earlier? Am I also to assume that this could also be found on the plugs? And the significance,if that turns out to be the case? Thanks...