Z900 re-jetting required?

[tobro]

I am rebuilding a 900 engine and had planned opening up the capacity a little. However because the machine shop messed up with th rebore and scored one of the liners, I have now been forced all the way to Wiseco 1045cc. I will also be also running a Vance and Hines 4 into 1. The carbs are standard '76 26mm Mikinu's.
Can anyone tell me whether or not a re-jet will be necessary and if so, how do I determine the jet size?

[Pigford]

More than likely - try going up 10% on main jet and maybe raise needle a notch - pilots may need to go up a size too

Every engine is slightly different - same as those old aorn carbs

[hanskloss]

not 900 and VM28 carbs but might be usefull, when 1015 - 17,5 pilots, 115 mains, now 1075 Wisecos, previous setup turned out a bit lean reading the plug colour although the bike run OK, moved to 20 pilots and 120 mains and it runs very well and the plugs are proper colour now. Used to run VM26 (17,5+115), after fitting 28mm Z1R/ST carbs the bike pulls stronger around 3500-5000 rpm, worth trying

[tobro]

Many thanks for the info guys. Gratefully received. Cheers

[mikeyoz1]

all you need is this or28 smoothbores or you can use the 26 and bore out 20 mm. The original cams to me will not do it . the pipe is it chrome or black ?Has the crank been wielded ?
Keep this e bayer on you watch list . He is the z1 king on e bay
hanskloss on the jets and polit / Pigford on the needle but you going to have to play with them . Also you need to snyc them


http://www.ebay.com/itm/360497016297?ss ... 1438.l2649

[mikeyoz1]

Just found the smooth bores


http://www.ebay.com/itm/380492518279?ss ... 1438.l2649

[tobro]

Thanks Mike.
Pipes are chrome. Not sure about the crank as I have concentrated on the top end so far and have yet to split the bottom, but it is on my radar.

Thanks for the link. Would 29mm Smooth Bore make much difference?

[mikeyoz1]

Just found the smooth bores


http://www.ebay.com/itm/380492518279?ss ... 1438.l2649

The 28 ,Sorry posted the wrong link

[hanskloss]

the ones from the "wrong link" are VM28 I have fitted/jetted now - a cheap mod and good improvement over VM26, the 29 smoothbores will probably go for proper money, heard legends about how good they are but not sure if it's worth the price for everyday use

[mikeyoz1]

hanskloss take a look at the wrong link again

[hanskloss]

Z1R carbs ?

[mikeyoz1]

Z1R carbs ?

yes
Dragbike KZ Z1R Mikuni 29mm Smoothbore Carbs Drag Bike Vintage Z1 73-84 Kawasaki

29 not 28

[hanskloss]

worked it out, I thought you meant 29 smoothbores and posted 28 link, but you meant 28 and posted 29 link

[mikeyoz1]

worked it out, I thought you meant 29 smoothbores and posted 28 link, but you meant 28 and posted 29 link

Check out the price they went for

http://www.ebay.com/itm/380492518279?ss ... 1438.l2649

[Z1parR]

Kinell