Gearing...................still !!!

[69chris]

hey guys,

i started a 'what sprockets' type thread before the meltdown and am no further forward....................... slack t**t eh

anyhow its a bit more pressing now as im having to use the 11R for work everyday and its.............well, its just wrong

iv got zrx1100 running gear on it, currently still using the standard 45t rear and have fitted an 18t up front,

its reving its head off at motorway (ish) speeds!!! it was fine before as i was working local but now its a pita, as most of my daily ride is on my very own private, highly secret test track its topping out at about 120, this isnt a huge problem, its just that its reving real high at 80-90 and fuel is going through it at an alarming rate!!!

iv ordered a 42t (smallest jt list) so hopefully that'll help, just wondered what size you guys are running with 17" wheels ??

cheers all

[FOZ1A]

Chris, snap! I am running zrx 11 rear end on the Rickman with the same gearing, and its revving its tits off!! So 18/45 give a final drive ratio of 2.5, original z900 etc is 15/35 gives 2.333 ratio, so if you go 18/42 it will give you 2.333! let me know how you get on, as i intend to do this over the winter.

foz

[Ginger Bear]

I guess a ZRX11 rear is 17"
My 1170R project runs a 17" rear wheel & 18/40 sprockets & is a little 'lazy' (Great on the motorway). I had considered going up one or two teeth on the rear, so 18/42 sounds about spot on.

[garyd]

Chris, snap! I am running zrx 11 rear end on the Rickman with the same gearing, and its revving its tits off!! So 18/45 give a final drive ratio of 2.5, original z900 etc is 15/35 gives 2.333 ratio, so if you go 18/42 it will give you 2.333! let me know how you get on, as i intend to do this over the winter.

foz

Just a comment...the gear ratio will be the same but you havn't taken into account of the different size wheel...a 17" will go less distance for each revolution so gearing will need an even smaller sprocket on the back to get it to go the same disatnce for equivalent revs of the engine.

Can anyone measure the diameter of the std wheel including the tyre & I'll try to work out what sprocket is needed....I'm suspecting it will need to less that a 40 tooth.

[garyd]

I know we can get 18 tooth 'off the shelf' but what's the biggest engine sprocket that will fit.

Could be time to bite the bullet and order a batch to be made of 19tooth from Talon.

[Ginger Bear]

I think there is a little confusion here.

69chris is referring to the later 'J' type engine that has a final reduction ratio of 2.733 41/15

FOZ1A is referring to the earlier Z900/1000 engine that has a final reduction ratio of 2.33

From my own experience when using 17" wheels on the earlier model, a 19t front sprocket with a 40t rear still left the bike a little 'revvy'. Ideally a 38 or 39t would have been spot on, but I had chain clearance problems with the chain running across the top of the swinging arm, because I'd 'jacked' up the rear end, to get back the ride height I'd lost fitting smaller wheels.

On the later 'J' type motors, (17" wheels) I fitted a 19t front & a 40t rear, it did 80mph @ about 3000 rpm, clearly not ideal. I now have an 18t fitted & it's still a little overgeared, but quite useable.

[sanderz]

Maybe of some help (for early Z1's although some valuable information in there)

Prev posted by Simon Grilling in '07
http://z1ownersclub.co.uk/forum/viewtopic.php?t=894

[Ginger Bear]

Good find that Sanderz

Interesting reading about even numbered sprockets.

[69chris]

thanks for the input guys and sorry for the confusion, as GB says i was refering to the later gpz/j type motor,

sprocket should be here by the weekend so i'll chuck it on and report back..... well, thats if my rev counter starts to behave itself, go over 5k and its started going mental, swinging all over the place,

i think the ole things objecting to being forced along the motorway daily, it clearly likes it even less than i do

thanks again folks