Z1200 runnin 6 miles per litre..

My z1200 uses 1 litre for 6-7 miles when just driving on small roads between 30 and 55 miles per hour.
It has stock 28 mikuni Vm carbs with 122 main jets 20 pilot jet and 395 webcams.
feul bowl level is within specs although a bit on the high side.
Main jet is still a bit to small but running to rich in the low's and mids (stock needle 3 clip).
cams set at 104,5 and 108 degrees (gives torqeu)

should lower feul bowl help feul economy and better low+ mid range???

or what does your big bore burn???:dry:

i'm running 117.5's and a 20 pilot on the 4th clip. i have vm24's. I get crappy mileage but i'm on the throttle a bit.
I don't think lowering the float will help you. unless you are running rich because of the floats.

Oh boy. Litres and miles :woohoo:

Lets see. Rough calculation using 6 miles that would be about maybe 24 miles per US gallon or 10 litres per 100km which would be quite thirsty. Thirstier than my Pontiac minivan but not as economical as my daughters Toyota Yaris :laugh:

What type of bike is being discussed? A KZ1000 with big bore kit? Is it a 1015 or J motor? What carburetors are being asked about? Z1 carburetors? 28 w/pump? What type airbox? No way to answer this type question intelligently without some basic info.

It is a kz900 engine with kz1000 jugs bored to 1200cc. Has stock carbs, Vm 28mm, no pump, stock needles on 3rd clip, only bigger 122,5 main and 20 pilot jets.
Stock airbox and filter. Exhaust are stock pipes which are made to a 4 in 2 systeem with reasonble universal long mufflers (cilinder 1 and 2 togheter and 3 and 4).
395 webcams, cams lobes set at 104,5 (intake) and 108 degrees.
Hopefully this is more info

more info .. dyna ignition and coils. She starts at the first kick

I really don't think you can bore a 1015 cylinder to where it will have 1200cc displacement. Perhaps new sleeves were added to make the displacement that large.

When you say the airbox is stock and the carbs are stock, I assume you have a stock 76 airbox? The carbs for a 76 KZ900 are VM26 so if there is no pump, the carbs are either from a Z1R OR from an early Z1. If the carbs are from the early Z1 (73/74) they will have two screws holding the tops in place and external sync adjustment. If this is the case, the jetting is a bit much for the main jets but not by a whole lot. I would stay with #120 or #117.5 mains and the pilot jet doesn't have a lot of options. If you have Z1R type VM28s with three screws holding the tops on, you should try #17.5 pilot jets and about #112.5 main jets. Hard to rejet carburetors when you are not sure about them plus you have a lot of engine mods.

your correct George, it has bigger sleeves which can be put in a z1000 jug. Carbs are with the 2 screws on top, early Z1 B type and z1 B airbox.

Thanks for your reply!! I'l try something tonight.

If you have Z1B carbs w/Z1B airbox, you should not be terribly rich... sounds like it is jetted about right although I think you could go back to the OEM stock size #17.5 pilot jets... I would start looking elsewhere for the source of your somewhat poor mileage. Cam timing? Tire pressure? Ignition timing? The jetting just doesn't sound terrible... pretty much what I would expect to work. The only thing that comes to mind are the needle jets. If they are worn, it is difficult to see and they will ruin gas mileage. The needle jets are the metal bits that sit atop your main jet holder tubes that the jet needles fit into. They can get oval shaped from wear and ruin your fuel mileage. It wouldn't hurt to replace them, if you can find new ones. I am not sure where you can find them... you will have to get their part numbers as the kawasaki.com website doesn't have fiche for any of the Z1 models. I can't recall off the top of my head whether the Z1B needle jets are the same style and size as the VM26 carbs from the 76 KZ900... I do recall for sure that the needle jets are significantly smaller and shaped differently than the earlier Z1/Z1A carbs. You might try contacting Jeff Saunders at www.z1enterprises.com as he MAY be able to get a set of needle jets for your Z1B.

the needle jets are different O-6 for later models and O-8 for previous. Difference seems to 0,1mm or so.
I swopt them earlier with indeed the 26mm....
Changed also pilot jet back to 17,5. Now dark up here and rain so the test ride has to wait. I'll let you knoa the results.

Please send some rain our way. Drought is tiring... although once it starts raining in South Texas, it never seems to quit.

did make a testride this evening for about 40 miles and twisting the throthle in differnet ways after rejetting to 17,5 pilots and O-6 jet needle. Main is still 122,5 and it pulls great up to 11.000 rpm. Difficult is that it did the same with the 130 main jet on 4th clip but then it was running way to rich in the mid (up to 7K).
It now picks up much better in mid, top is unchanged....

But It is now pinging when I open the throthle wide open at 4000 rpm and pinging occurs between 6-8500 rpm. When gently opening the throthle and quickly opening to full throthle at 8-8500 there is no pinging so it seems to be a needle issue?:blink:
Is this to solve using a bigger main jet or just simply reclip the needle to 4th or 5th???

even retarding ignition 5 degrees was no cure....