81 Z650 F2, carbs, fuelling, jets and pipes

[m1ks]

Hi all,
First time on here, I was recommended to this site by a friend who has a Z1B engine propelling a Harris frame around.
I've been a Kawasaki fan ever since I started riding having had various models.
I've just gotten a Z650, (as per the title), as I was leaning to a more classic style and always liked the Z1000's (Mad Max, Goose and Toecutter have a lot to answer for).
I was led to believe it was an 82F3 though in fairness to the guy selling he wasn't very model or tech savvy.
Frame / engine numbers indicate it's an F2, (likewise the flatslides).
Now the bike has clearly been 'rebuilt/restored' at some point before the guy I bought from had it.
It has K&N type pod filters on, Motad silencers, (4 into 2), aftermarket headlight, no indicators, and non standard front mudguard.
Inside the tanks not the prettiest but clean enough and not sure on the fuel tap, (it's a ON / RES / PRI vacuum feed type), and the seller told me he didn't think the reserve worked.
It's pretty tidy all round and starts well on the button.
However, the problem and questions:

Starts and runs fine, accelerates well up to about half throttle
in 5th e.g. it'll run steady up to 5000rpm, 65/70mph, then open the throttle and it goes
Bllllllllaaaaaaaaaaaaarrrgggghhhhhh!
It just stops pulling, in relation to throttle opening this happens above half throttle in any gear.
Blueing of the headers indicating leaning at higher revs.
First thoughts to my mind were that the carbs had been changed because I thought it was an 82 which should have CV carbs, (now revised that after checking frame numbers etc)
I'm guessing that when it was restored the filters were replaced with the K&N's but the carbs were left with stock jetting, also the pipes are bog standard aftermarket replacements.

If anyone knows the stock jetting for me to check against mine that'd be great.
On the carbs there are the overflows as per and then looking from the left each second carb, (2 and 4), have an inlet / breather / vacuum style pipe attached to nothing, theres a vacuum there when running but not sure what these are for?
Also what looks like an air bleed screw at the air inlet.
I'm not familiar with flatslides and setting up as mainly have had CV carbs so would appreciate pointers to jetting, needle positions and mixture screw locations, (is there just an air bleed or a low running mixture screw too?)

I've just bought a standard airbox off eBay so will see if this restores order, (not bothered about the pod filters and other than when good breathing and balls out performance is required I have always found them to be an unecessary pain to get set up without flat spots), standard performance will be plenty adequate for the use I need, lazy riding, commuting, pillion, luggage.
Apologies for the lengthy first post but wanted to get as much info in there for you zed experts as possible.
Cheers,

mike
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[zedrider]

thats a very tasty z there my freind . i will have a look at my zawa book of words tomorrow see what it says . best wishes Ian

[GUYZED]

Hi Mike and welcome to the club - your first post should have been on the NEW HERE bit, so go on introduce yourself

Nice looking Z650 you have there - are you going to put on proper clocks and junk the little custom ones.

I know it just might be me but the front mudguard is on the wrong way round

[compo z1r]

hi' and welcome mike can only find info on the 24ss mikuni's
main jet 100 pilot, 16 needle jet 0-8 pilot srew setting3\4+1\8 turn out from stop, float hight 30mm+1mm nominal. on the flat slides first get them balanced and a dyno run for the fuel set up.

[kev edwards]

Hi Mike,the carbs look like standard carbs to me, the pipes between the carbs as you describe them should be breather pipes which go into the standard air box prior to filter, the single screw on the outer side of the carbs is the pilot circuit air screw these as a rule are 1 and 1/4 turns out plus or minus 1/8 of a turn,the needle height is normally on the middle groove, but on the needle itself the last number relates to the groove it should be, working from the top down. If someone has just put the k&n's on without re jetting this will create problems, also check that the vaccum take offs on the inlet stubbs have caps on them and that one goes to the fuel tap. It would probably wise while it is runnin to spray wd 40 on the inlet stubbs to see iff there are any air leaks if the engie dies off you have a leak, as you have a new air box fitting this first may sort the problem out anyway,
If you have the VM24SS carbs these are the specs for them

UK MODEL -------------------------- US MODEL
Main jet 102.5 ---------------------- 92.5
Needle jet 0.4 ---------------------- 0.5
Jet needle 5cn15-4----------------- 5cl30
Pilot jet 15 ------------------------- 15
Starter jet 40 ---------------------- 35
Float height 23mm + or minus1mm

Good luck

[m1ks]

That's fantastic, thanks guys for reponding, Hopefully the standard airbox will be here for the weekend and I can chuck it on and see how it goes.
With luck the fella who rebuilt will have left everything standard and the fitment of this will sort the lean running.
I fully intend to clean the carbs anyway and set the mix and balance them so the above info will be invaluable, I guess i'll have to bite the bullet at some point and fork out £25 for the Clymer manual as that covers up to 83, (the haynes only up to 78 I think?), i'd so much rather spend that on shiny bits for the z though.
I'm assuming that the model only used the one type of Mikuni Flatslide before changing to the 32mm Mikuni CV's?
The inlet rubber vacuum pipes are blanked as they should be and theres a vacuum feed pipe to carb 2, from the petcock, i did wonder if the other two would have fed to the air filter so, good to know that, thanks.
Will update when i've tried the replacement box.
Can anyone who's set these up confirm whether theres a slow running / mixture screw or just the air bleed screw, if that's what it is of course?
I can post a close up pic of the carb is that'll help?
Re the mudguard, you know, you're right, it is fitted back to front, It never even twigged, I don't know if that was deliberate or not? Doesn't look bad as is that said but if I can get a genuine chrome one at a decent price i'll probably go that route, in the meanwhile i'll switch it round and see if it looks better like that.
Thanks for the kind comments and as a closer i just have to show you the reg, I was quite pleased with this

In fact, heres a close up of the carb too.

[m1ks]

Incidentally i'd love to replace the little custom clocks with genuine ones and an idiot light display, it's a bugger guessing when you're in neutral, I'd forgotten how annoying that was when I had my Z750 hardtail chopper, surprising how you miss a simple light.

So, if anyone has a set of cheap original clocks? let me know please.

At the moment the rev counter bouncing between 5K and 6K is amusing, not sure how long for.

[kev edwards]

Hi Mike , there is only the one slow running circuit srcew on these , this adjusts the air intake for slow running , also your year of bike should have the accelerator pump type carbs on it , if not they would be the earlier model type , my brother has an 82-83 csr , that has cv carbs and it runs sweetly with those on it , if yours continue to play up it may be worth sourcing a set of these.

Kev.

[mick znone]

Mick say's...."So, if anyone has a set of cheap original clocks? let me know please.

At the moment the rev counter bouncing between 5K and 6K is amusing, not sure how long for. [/quote]"


I wouldn't advise a cheap set of originals if you don't like bouncing needles Mick, they are mostly past their sell by date. may have to have a set restored mate.

[BShaw]

If you cant sort it with the carbs check the valve timing it wouldn't be the first one that's been put back together one tooth out.

Welcome BTW

regards

[Taffus]

Hi
Try here for info http://www.kz650.info/
or here http://www.kzrider.com/ pm me your email address and I can let have some pdfs re servicing.

I'll be away from the computer until Sunday evening as I am going to Wales and the SW west meet

[m1ks]

Taffus, thanks for the links, PM sent.

Bshaw, will check everything as I go, full service on the cards too, something always do when I get a new un, don't think the valve timing is at fault though, from experience it seems like a fuelling problem, (have had similar with electricals but batterys new and everything appears OK that side)

Mick Z1A, how much does a refurb go for on a set of clocks?

Thanks again all for the responses

[irhobotolo]

[quote="m1ks"]

I was led to believe it was an 82F3 though in fairness to the guy selling he wasn't very model or tech savvy.
Frame / engine numbers indicate it's an F2, (likewise the flatslides).



First thoughts to my mind were that the carbs had been changed because I thought it was an 82 which should have CV carbs



mike
Mike, The 650F2 had slide carbs as standard as did all Z650s except the 650F3 which was the last model made for 83 which had CV carbs. Your bike looks like a 82 650F2 with the original carbs.

[zed1015]

Yep those carbs are std z650 ROUNDSLIDE mikunis NOT flatslide and will be easier to set up with the aftermarket filters than cv's would.

[m1ks]

Right,
Thanks again, not having had experience with roundslides or flatslides I wasn't sure, I was basing my guesstimating on bits of info i'd googled, most sources state all models prior to the CV fitment state flatslide, hence thinking that's waht they were, so thanks for clarifying that.
Other than the slide shape between the two does this have any bearing on the operation?
The thing I knew for definite was that the F3 had CV's so immediate throughts were that the 'rebuilder' had sourced different carbs until i'd checked the frame and engine numbers which proved it to be the F2.
Still awaiting the airbox, so will update asap.