black sooty plugs(its not on my storm)

[TonyW650]

Hey guys,
I know iys not storm related but it is bike related, so juat thought someone might be able to point me in kind of right direction, I've got a 35 year old z650 not been on road since 2009, engine has been turned ovwr on kixk start regular. Finally decided to get her running over week end, but the plugs are getting black and sooty is that a over rich mixture or what?
It dont look like oil deposit, just sooty?

[lloydie]

How long are you letting it run for ?
If its not that long the plugs will get sooty .

[TonyW650]

Left it running for about a hour, it used to be prone to sooty plugs but seems to have got worse, the z'd no wherr near standard.
Would old fuel or anything like that make a differance?
Its blowing out a bit of black smoke when you blip the throttle, like its running rich

[lloydie]

Yep sound like its running rich .
When was the last time the carbs were cleaned and new fuel can only help :-)

[TonyW650]

They are the old type slide carbs so not much in them, I stripped and cleaned thw float bowls, floats and needle valves at week end to get it running,
Had a set of b5es new ones laying around and they went black after running in it for half hour or so.
Would stuff like float height etc make it run rich, I have noticed the inlet rubnera are a little cracked but if more air was getting in aurely it would run lean?
Bear in mind its running pod filters aswell and has had them on since before I got it, would a standard airbox make any differance?

[VTRDark]

Yes float height if incorrect will make it run rich, also check the condition of the float needle valves and seat. If float height is all OK then move onto the jetting side of things. More air does not necessarily mean that it will make it lean. Because of the pressure differentials more air can sometimes draw more fuel up. If you have any air leaks then get them sorted as they will affect the mixture. If the bike has been sitting around for some time then the carbs will need a good strip down and blast through all the passageways and jets with some carb cleaning spray. The pod filters will complicate issues for you with jetting as the standard jet sizes will more than likely not be right for it. Also make sure that the choke is functioning correctly and nothing is sticking.

(:-})

[Golgother]

Hi

Previous replies are all spot on especially cleaning carbs with carb cleaner and the often overlooked float heights.

With 34 year old carbs and a long lay up there is every chance they will need an overhaul with, new jets, float valves, needles, also check the balancing and that the needles are all set on the same groove.

What ignition system are you using ?

Cheers
Matt

[TonyW650]

Matt its got a Boyer ic unit and stator plate.
I've cleaned the earth to the engine, cleaned up all the factory bullet connectors, checked the coils, its got later GPz coils fitted, cut back the hit leads and refitted the NGK screw on caps.
Clean and soldered on the leads from the ic to the coils, made a little sub loom up. Its sparking better that it was.
The carbs ain't that much of a pain to strip down, they are the old style Z slide carbs so no diaphrams etc....
I'm wondering about hunting down a air box and replacement inlet rubbers, but old z'd bits are getting expensive now

[Kev L]

If the rubbers have just gone stiff and not cracked you can evidently recover them by soaking them in some wintergreen oil (or some such). There was an article in Practical Sportbikes the other month. I will have a look and see if I can dig it out for you if you like.

[Golgother]

Hey Tony W650

You seem to have the ignition locked down just double check that it is sparking at the right time, the advance, if too early can cause sooty plugs but not at tickover.

Nearly forgot, check your pod filters are not clogged.

TBH you will not likely get pod filter to work unless you use a dyno to measure the fuelling through the complete rev range, whilst the motor is under load, then you will still most likely have to replace some carb parts.

I know what you mean when you say airboxes & rubbers are gettting expensive............

Cheers
Matt

[TonyW650]

Golgother
Even considered going back to points and condenser, but you try getting hold of the old stator plate now, they are like rocking horse poo!
I know when I press the horn lol the spark is better so wondering if I've got a crossed earth or something, did contemplate running a earth up from battery direct to coils , but I can't remember if it uses the frame/engine as neg or runs a neg through the boyer unit to the coils, I can't see if it does the latter part that it would do any harm.
Just kind of stumped.
Think the carbs are going to have to come apart and check all the needles etc against the chart, its got to be something g simple as there ain't a lot to these old Z lumps lol