TOPIC:

Today I have approx 4500rpm on 90kph / 56mph.

These a normal crusing speed in Norway for me.

The gas tank I have is around 16l I think.

I was thinking by reduce the rpm can also reduce the gas consumtion?

I maybe need to go down to 4’th gear to over take other....? Now can I just use the throotle.

Its a 750 engine with overborr 810 kit. Carbs in from a 650 engine.

I need to find the gear ratio I have right now.

Hey Gord! Just divide front to back. Like on a Z1/KZ900 15th front and 35th rear. The final gear ratio is: 2:33.
Too bad, Do you order from USA? Z1 enterprise has a 16th front on clearance for $10.00 bucks. I have no clue what your sprocket cover looks like or if it will acomodate a 16 front sprocket. but that will gear you down.
www.z1enterprises.com/maintenance-parts/...rshaft-sprocket.html

At JT Sprockets.com, go to the catalogue section & enter your bike or KZ750. Then choose a model from the list. Since your motorcycle has an 810 kit, I guess any 750-4 could be used. There should be a list of sprocket combination for the model you choose. Next, find your sprocket ratio which is dependent upon what sprockets you have.To lower the revs, choose a ratio that's lower than your current setup.

example. jtsprockets.com --- KZ750-L3
The stock sprockets & ratio are hi-lighted in red.

Click the sprocket part numbers to see what other models use the same sprockets. Then check eebbaayy.
Z1Enterprises.com should have the JT Sprockets you need, but the extra search may come in handy.

Not sure of the difference with a 650(750), but I'm at 4500 rpm at 70mph in fifth on my 1000.

What I have now is :
Sprocket - Front - 530 - JTF513 Series - 16 Tooth
Sprocket - Rear - 530 - JTR488 Series - 38 Tooth

16 / 38 = 0,42


My English is not so good
What I wondering about, can it be a good idea to decrease the rear sprocket to
get lower RPM and then save fuel ?


1. Will the bike be "dead" to use with another ratio ?
2. Will I save fuel ?

Carbs I have is : VM24
Piston kit is : Wiensco 810 big bore

The 1980 kz750E1 (4 cylinder) came with front 13 tooth and rear 33 tooth sprockets. (630 setup)
33/13 = 2.54

You have F 16 and R 38.
38/16 = 2.375 . This is quite a bit lower than stock.

I put a 530 chain and sprockets on my 750 two years ago
I have F 16 and R 41 sprockets.
41/16 = 2.56 . I would not want a lower ratio.
At 100kph I see about 4600 or 4700 rpm but my tach is crazy

Thank you, so I understand I`m already low on the ratio, so I should not go lower on ratio.
The bike feels fine with these setup I have enough power on whole range...

I see the gas tank could be bigger on longer trip...

But I have had to rich fuel/air mix, have improved that a lot so I hope I can get some some more km/miles on a tank now.

VTEC wrote: Not sure of the difference with a 650(750), but I'm at 4500 rpm at 70mph in fifth on my 1000.

What sprockets and ratio have you ?

gordone wrote:

VTEC wrote: Not sure of the difference with a 650(750), but I'm at 4500 rpm at 70mph in fifth on my 1000.

What sprockets and ratio have you ?

Never counted? But they're OEM. Bought the bike new and did chain n sprockets once with the same ratio.

Don't know if it applies on this bike, but I went aftermarket with the front sprocket (forget the brand?) and got a nasty chain whine. The offset of the sprocket wasn't even close, so the chain was out of line. Corrected with new OEM sprocket. Guy at a Kawi dealer said that's always the case on my bike. Have to use Kawi part.

By the way. Love the DuPont Chain-Saver lube!

First thing I would do is junk the VM24's way to small of a carb for a 810 motor. Find a set of VM28's so the motor will make the hp it should then look at gearing.
On my 810 GPz750 motor with a 530 chain I run 16-42 or 16-45 sprocket's

Save this in your favorites:
www.gearingcommander.com/

zukdave wrote: First thing I would do is junk the VM24's way to small of a carb for a 810 motor. Find a set of VM28's so the motor will make the hp it should then look at gearing.
On my 810 GPz750 motor with a 530 chain I run 16-42 or 16-45 sprocket's

Always nice to have some future project with the bike (increase power)

The RPM towards speed will not change with more HP.... but off course I can get even lower on the ratio then.