Kawasaki Sportsbike Riders Club - Australia - Online Forum

I've got a new project on the go, it's an oldskool wheelie bar Dragbike from the 80s powered by a Z900 engine with an alleged MTC 1200 kit & all the fruit in it, the motor was set up running twin 40mm DCOE sidedraught Webers, I have the carbs & manifold but the carbs are missing the jets & emulsion tubes which are ridiculously 'spensive so I'm looking at using bike carbs on it.
I've got a few sets of 4 cyl bike sidedraught carbs here & the spacings are pretty close but I'll need to source some inlet manifolds because the Weber manifold bolts directly to the head so I don't have any which brings me to my questions -
What is the I.D. of a standard Z9 inlet manifold?
Are there any other model/year Kwakas that have a larger I.D. & use the same mounting flange (he he, flange...snigger) eg. Z1000, GPZ 11, etc.
Does anyone (APE, MTC, V&H, etc) make an aftermarket manifold to take big carbs?
If I can't get a manifold that bolts straight on, I can get some flanges laser cut, turn up some stubs, weld them together & use some silicone hose but time is a factor so I'd be happier with the easy option if there is one.
Or does anyone have any DCOE jets & E tubes laying around?

I'm itching to get this thing running & point it down the 1/4, it'd sposed to make 140 HP & the chassis weighs next to nothing so I reckon a low 10 isn't out of the question.

Cant help u with what ur asking... but back in 1980 when i built my A comp bike, we toyed with the idea of what u got... but at the time was decided not to go down that path, as setting it up and tuning was a bitch...... we opted for big smoothbore carbs, way easier to tune... tho at the end we were on meth fuel..

But what we did do in 82 was go altered, as u can then run different fuel supply.. we fitted a hillbourne mech fuel injection... on meth, that was A ok... tho never got to sort it properly.... it sort of fell over at speed.... but getting 10 or low 10s on bars should be no probs...

Kwak addict wrote:.....I've got a new project on the go, it's an oldskool wheelie bar Dragbike from the 80s powered by a Z900 engine with an alleged MTC 1200 kit & all the fruit in it, the motor was set up running twin 40mm DCOE sidedraught Webers, I have the carbs & manifold but the carbs are missing the jets & emulsion tubes which are ridiculously 'spensive so I'm looking at using bike carbs on it.
I've got a few sets of 4 cyl bike sidedraught carbs here & the spacings are pretty close but I'll need to source some inlet manifolds because the Weber manifold bolts directly to the head so I don't have any which brings me to my questions -
What is the I.D. of a standard Z9 inlet manifold?
Are there any other model/year Kwakas that have a larger I.D. & use the same mounting flange (he he, flange...snigger) eg. Z1000, GPZ 11, etc.
Does anyone (APE, MTC, V&H, etc) make an aftermarket manifold to take big carbs?
If I can't get a manifold that bolts straight on, I can get some flanges laser cut, turn up some stubs, weld them together & use some silicone hose but time is a factor so I'd be happier with the easy option if there is one.
Or does anyone have any DCOE jets & E tubes laying around?

I'm itching to get this thing running & point it down the 1/4, it'd sposed to make 140 HP & the chassis weighs next to nothing so I reckon a low 10 isn't out of the question. .......

I have all the specs to run DHLA 40mm DellÓrtos on z-based motors up to 1200cc. These are close but not quite the same as Weber specs. I have bought all my jets/emulsion tubes/air correctors etc from a bloke on ebay in Italy - great service, quick postage - the guy is a legend. But I don't have an inlet manifold .......yet..... - the Italian connection also does Webber stuff if you need it....

None of the US manufacturers make any aftermarket kits to bolt up side-draft carbs to zed heads. The biggest problem is the spacing of the standard inlet manifold bolts. The maximum size carbs you can bolt up to any air-cooled zed head - using OEM inlet rubbers - is about 36mm. Z1000J or GPz1100 inlet manifolds are the go. But they are no good for anything bigger. The biggest carbs used back then were 34mm CV carbs on the J models, and 36mm throttle bodies on the injected models.

Debben Performance in the UK have a great site and they offer large inlet manifolds for Z heads, but I have not sourced these as yet to determine the ID of the inlets. If they are up around 42-44mm *ID* - then you could conceivably bolt up some 38 or 40mm FCR flat slides. These would be a better carb for a drag bike. Apparently the Debben manifolds also have the right bolt spacing for a Z head. Here is the link to these manifolds - just scroll down to the bottom of the page for these .. Debben Performance

Do you have the inlet manifold to suit the Webbers ? Last year I sourced a big slab of billet T6061 so a mate of mine who works at the ANU could turn this into an inlet manifold to suit the Dell'Ortos. He can do this with a bit of work ........but if you have a manifold that could be used as a template that would make this job heaps easier......

Standard Z inlet manifolds have an ID of between 32 and 34mm - depending on wether 26mm or 28mm carbs were being used. The largest inlet manifolds - those to suit injected 1100's - are about 38mm ID.

Interestingly - one of the most succesful sidecars that ever campaigned back in the 70's - was the Chesterfield Wedge. This had a z900-based motor - and also used 40mm side-draft carbs !! They knew a good thing when they were onto it even back then . This motor just used real simple steel manifolds that bolted from the carbs straight up to the head. Flanges and stubs - easy E.

Would be great to see if you can get these carbs working on the drag bike. I reckon the Dell'ortos will be the ducks guts on my Period 5 bike.....just need that manifold !

You're a legend Gos, I knew you'd be the man in the know, thanks for all the info. I'm definitely keen to know about the Weber jetting specs.

Yep, the Weber manifold came with the bike, funny you should mention about the sidecars, the motor & carbs that came with this dragbike chassis is out of a roadrace sidecar from back in the day, old Les - who I got it off - raced the outfit with some success then retired it (he still has it), pulled the motor out & bought this ex Pommie Pete rolling drag chassis to put it in.
That's as far as it got until I rescued it.

Speaking of the old bloke I got the bike off, I'm gunna get some pics of his garages nextime I'm there, you should see all the GOLD he has laying around -
The first Lamborghini Countach imported into Australia plus a Urraco, a brand new Cosworth Sierra racecar shell, a Hilborn injected Formula 5000 Chev race motor, a Mini Cooper S, The first TZ 700 in OZ plus a spare motor, a TZ 250 with a Kwak 750 triple in it !! (one day it will be mine ) an old Kwaka W650 race engine ??!? & that's only what I've seen without digging - the place is jam packed.
All these cars & bikes are unfinished projects & are in various states of repair or disrepair (yes, including the Lambo's) & there's another garage I haven't even been in yet. It's a scroungers dream!

It might be quicker/cheaper/cleaner/easier if you use my manifold as a pattern to get one cast instead of carving one out of billet, of course it's up to you but I'm happy to send it up to you so you can have a look at it & decide then.

Kwak addict wrote:.... I'm definitely keen to know about the Weber jetting specs.....

no probs mate I will dig up the specs and post them here for you. The book I am using to get me through all the weirdness that is side-draught carbies - is This Book

Kwak addict wrote: a TZ 250 with a Kwak 750 triple in it !! (one day it will be mine ) an old Kwaka W650 race engine ??!? & that's only what I've seen without digging - the place is jam packed....

there was a TZ750 fitted out with a H2 in Sydney many years ago - it was registered !! I could spend a week in a place liek this

Kwak addict wrote:.....It might be quicker/cheaper/cleaner/easier if you use my manifold as a pattern to get one cast instead of carving one out of billet, of course it's up to you but I'm happy to send it up to you so you can have a look at it & decide then....

Mate that would be awesome if you could - will pm with details