Plugs. What's wrong with this 1?

Bike was runnig a bit rougher than normal so it seemed new plugs might be in order. Imagine my horror when I found out I hadn't replaced them in a year or 12,000 miles.

My question is: What, if anything does the plug from the front cylinder indicate?

Next to it is a new one, and the pic below that the rear which seems ok if not a little sooty.

[Biker Biggles]

Front one looks just well used to me,rear looks a bit rich.No oil I take it? Rear choke plunger OK?

There are some pics in the very back of the haynes manual.... I'll have a look and see if I can match it up.


EDIT: its a match with Normal and a little bit of Worn. FRONT

EDIT 2 : the REAR plug is "Carbon fouling - Dry, black sooty deposits leading to misfire and weak spark. Caused by an over-rich fuel/air mixture, faulty choke operation or blocked air filter.

Originally Posted by Biker Biggles

Front one looks just well used to me,rear looks a bit rich.No oil I take it? Rear choke plunger OK?

Well I've just changed the choke cables today actually, together with the throttle ones. Probably never run again. I was told that the choke on one may have been sticking. Trouble is, after all that effort the old cables felt fine.

Doesn't the rear cylinder run hotter than the front?? That might explain the difference!

[yorkie_chris]

Bit rich, your's is quite free flowing setup, are you using split mains?

Can't see the colour of the insulator nose on the front plug, would be helpful.

Also choke plungers the cables not usually the problem, its crap getting into the plunger that does it or the splitter part, takes less muck to bind up there than at the cable. I always pack the spltter, plungers, cables and lever with grease to avoid this.

If its taken 12,000 miles to get to the point of running rough, I'd say it's alright, a set of plugs a year isn't going to break the bank.

Also a bit of copperslip on the threads might be an idea, doesn't seem to be any there in the pics and it massively reduces the chance of snapping a siezed one.

Cheers BB and DD

That sorta put my mind at rest, although I was thinking that the front was the problem not the rear.

Not sure if the rear runs much hotter than the front Billy. Tis watercooled after all.

Don't know if it's got split mains, ring mains or water mains YC. Was all set up for me by Jordans.

Yeah packed the splitter box and behind the plungers with grease. I always use copperslip on the plug threads, but I guess after all that time it's gone. The rear undid easily but the front felt "funny". Bit of corrosion and glup in there I'm guessing.

See how she goes now.

This is a complete guess - but might the front cylinder run slightly cooler because it's exposed to the elements and the rear one isn't?

That's a great tip with the piece of hoze holding the plug! Not seen that one before! I wish I'd known about that when I ran the FZR 400! They were a real bugger to reach!

Thanks for that!
C

IfI remember correctly, the rear cylinder is supposed to run slightly richer than the front one, because the front gets the benefit of a lot more air around it. If you think about it the rear cylinder is actually quite enclosed, and probably gets a lot of the heat from the front cylinder thrown its way!
They had a lot of trouble with the rear cylinders on the vfr's overheating because of this, even though they are also water cooled.