cylinder #6 not firing

[mike209]

I've swapped cdi with another unit, no imptovement, I have another cbx with c5 ignition, maybe I could swap this and see if it helps, also my compression gauge is $20 crap and I am not sure if I can trust it, if you guys can recommend some good leakdown tester I would appreciated it, I will have to make a list of things to check and go over everything again, mayba I've missed something.

[herdygerdy]

At the risk of appearing somewhat of a pedant, our CBX ignitions are not technically CDI (Capacitor Discharge Ignition). They are in fact TPI (Transistorised Pointless Ignition) - some may ask "What's the point?", but I digress.

To have it explained beautifully in layman's terms, check out this excellent article from the inimitable Mr Mike Nixon.

http://www.motorcycleproject.com/text/dohc_ignition.swf

Because you "have the bonnet" up at the moment, I am sure this will aid your understanding and diagnosis to either prove or disprove you have an ignition issue. As an aside, the only part that is not done in pairs for your ignition, is the lead from the coil down to the plug. Me thinks a failure of any other ignition component would also necessarily take out cylinder No. 1 as well?

And when you have a spare hour or seven, grab yourself a six pack of your favourite coldies and lose yourself here...

http://www.motorcycleproject.com/index.html#101

Should keep you quiet for 10 mins... : )

Enjoy and keep us posted on developments.

Cheers...Tony

[Mouse]

OK Mike, swapping in the C5 ignition likely won't make any difference.
Looking back at the photo of the N0 1 and No 6 plugs you posted. No1 appears clean No 6 appears to be sooty so ... possibly, No 6 fuel to air mixture maybe the issue.
Tony, your not being pedantic, my bad mind you, even the people who supply TPI replacement units call them CDI's .
It's Friday
have a great one all.

[mike209]

Mouse, my bad, plug on the left is plug from cyl#6,
If fuel mixture is the issue, would it create problem at higher rpm?

[Mouse]

Mouse, my bad, plug on the left is plug from cyl#6,
If fuel mixture is the issue, would it create problem at higher rpm?

Yes.
A too rich fuel/air mixture can cause all kinds of issues. One issue is that it can work like a rev limiter. A way to rich mix can drown the cylinder spark plug. The drowned cylinder is now a drag on the other cylinders and the engine won't rev to its potential. You can have an engine that will idle, but give it throttle and it will die.
It can also cause backfiring and or mis-firing at any rpm.

Fuel/air mixture is controled by jet sizing, the mixture/pilot screw, and air flow characteristics of the carb. If you pull the carbs again check that your jets are the correct sizes in the appropriate places and that they are the same on all carbs. The shop manual will give you the base mixture/pilot screw setting.(section 4-26)

It needs to be said that, Syncronizing the carbs does not alter fuel to air mixture. Syc,ing the carbs balances the variable flow characteristics of each carb with the throttle input.
Getting a perfectly running engine is a delicate balancing act between fuel/air ratio's and flow characteristics of each carb and then syc-ing all carbs with the throttle input.

This is easier said than done.
I have to have this done by others as my attempts have resulted in a worse running engine.