Z900 black smoke from all 4 pipes and wont idle

[BIGVERN]

Hi guys, I have dragged the old lady (a 1976 z900a4) out of the garage after a very long time (at least 3yrs) and thought I would get her up and running again and spend a couple of shillings on her.
Started with a the usual service items ( plugs, air filter, oil filter and oil)
remembered that she was boiling the battery last time I used her so got a new battery and a regulator/rectifier unit from z-power. finally as she deserved a treat I purchased and fitted an electronic ignition.

Fired her up and set off to get an MOT

Passed with flying colours so next stop was the post office for TAX.

She was now ready for a sunny summer!!!!!!!

First trip with 13yrs old son on board and she was flying. Then about 20miles into it we stopped at some lights and she cut out. fired her up and off we went. she then started to run rough and I was having to give her a big handful to keep her going.

Got home and decided that it must be shite in the carbs due to being laid up for so long.

Carbs off...... float bowls had a bit of shit in them which was cleaned out and Idle jet on no.4 was blocked. All cleaned and blown through with compressed air.

Carbs back on...... air screws out to 1 + 1/4

Then the problems started

Would not fire up at all and flattened the battery trying

Charged battery over night

tried again...... finally fired but would not idle

when reving over 2500 let go of throttle and revs stay they gradually drop to 900 then coughs and stops.

I have tred all differents screw settings from 1 to 2+1/2 but no help.

checked the electronic ignition which is bang on

checked the coils which are fine

fitted brand new inlet rubbers

checked plug gaps fine, although they are now soaked with fuel

cleaned and dried them
put back in .... no change

So can anyone help PLEASE

This is the problem........

Will not start with choke
When running will not idle
Holds revs then drops to nothing
black smoke from all 4 pipes

I have just been into the garage to remove the carbs again so that I can give them another clean and found a large amount of fuel had leaked onto the lower engine casing.

last time they were off I checked the float levels and they were perfect

PLEASE PLEASE can anyone point me in the right direction

The carbs are obviously chucking far too much juice into the engine and it is killing the spark.

Sorry its so long winded

Many Thanks
Graham
(I was a member many years ago no.730 and will be joining again especially if i can get the bike back on the road)
or
Anyone want a standard and unmolested bike with an agreed value of ?4000

Only kidding, would never get rid

[Pigford]

Hi BIGVERN,
where you based
As you've rightly deducted, running rich All you can do is get those carbs thoroughly cleaned out
Re check float valves & heights.
Sounds like pilot system is blocked. When you had the first run, the gunk in the carbs probably loosened & is now blocking the air ways in the pilot jets. These may need ultrasonic cleaning or similar as the fuel residue can be a bugger to shift on a DIY basis
If she ran OK for the first few miles, gotta be shite in carbs (95% sure)
Modern fuel can bung up carbs in less than a year if left standing

[BIGVERN]

Thanks for the quick reply

I am based in Cheshire near to Chester

Carbs are now off again and I am on my way to the garage to do the big clean up.

cheers
Graham

[chrisNI]

Also take your tap out of the tank and make sure it's not got a lot of crud gathered up round it that is making it's way into the carbs. You'll probably have killed your plugs too get some Densos.

[Russ]

A mate of mine used to throw a piece of rag under his seat (to polish his bike every time we stopped...sic) until it blocked his air intake. Took us a while to figure this out in a layby in the poring rain. Sure your not this dumb though. I concur with the other guys... got to be a carb situation.

[BIGVERN]

Carbs have been been stripped and completely cleaned then air screws set to 1 3/8.
Tank has been drained and cleaned out.
New set of Densos fitted

She roars like a lion and idles lovely

Just need a break in the weather to a road test her, but I think she is back to her former glory, if not better.

Thanks to all those who have advised me

Looks like I will have to rejoin now

Definately worth it though and look forward to seeing some of you in the future

Cheers
Graham

[Pigford]

Glad to hear shes A-OK now
Watch out for those DEEP puddles tho

[BIGVERN]

Cheers, I have printed off the membership application form and written the cheque.

post if off on monday

got the bug again

[davejames]

Is that you Mr Clayton ?? This is your area rep here, give me a shout when it stops raining and we'll go out for a run

[BIGVERN]

Dave long time no see,

got the bug again and spent a small fortune getting the bike back on the road for the summer.

going to rejoin the club and would love ride out.

will drop you a line when the rain stops, probably some time in 2009

should have spent the money on an arc!!!!

all the best Graham

PS will give you your kwaka book back next time I see you. Found it in the garage the other day....... oops sorry

[davejames]

Nice to see you got it sorted, you can come and help me get mine sorted now. It's been sat in the garage for the last 15 months, whilst I've been cruising around on a Zrx

I hadn't forgotten about the book, hope you enjoyed it

[Phil50]

hi Graham
sound very like my original problem when I first posted for some help from the members. My bike had also been standing for a year or so

I renewed all the jets with kit from http://www.nrp-carbs.co.uk/
Cheap and a really full kit of bits.

Did help but still smokey and fuel in the oil system I went round in circles until I checked the compression with a gauge from Halfords for ?18.00. All the rip off local garages wanted ?40 + for a test.

I found the compression down to 70-80 PSI. It should be 145-150PSI ideally but never lower than 110 PSI. I had to strip it all down and found the head coked up the valves all oiled and gritty. But most important was the rings were shot and the pistons scored badly and beyond help.

I hope your problem is less trouble but I ended up paying ?400 for pistons/valve oil seals/gasket kit ( Z-power) and ?100 for a rebore as I had to get 0.5mm oversize pistons. I did get so many ideas and help in here but I think the most important sugggestion was to check the compression. If that is far down nothing is going to work correctly.
Good luck
Phil
PS I am putting the head on Saturday and firing it up. hope it works for me.