new sprockets..... is it too much?

i'm getting new sprockts for my 78' kz650, and
i was wondering if the sprockets i ordered are going to be too much of a change. the stock set up is 16 front 42 rear and i'm changing it to 13 front and 45 rear. will that be too much? i deffinatly am look for a drastic change as the stock just dosen't have enough
acceleration. i'm not too worried about top end as i never ride this bike much over 80.

Wow, that 650 should do power wheelies with the new gearing!

You are changing from a 2.63:1 ratio (Stock) to a 3.46:1 ratio (13/45), so now at 80 mph the motor is going to be running real close to the redline rpm (9k I think), but it sure ought to get there fast.

Yeah, I think you overdid it a little

Post edited by: steell, at: 2005/12/11 11:18

Welcome to KZR dixie...

Here's a post in the Archives with some gear ratio info: Gear Ratio Make sure you read to the bottom as some info was reversed.

Give us some pictures of all your rides. What others do you have besides the 650?

yeah i was hoping to get the wheel up in the air:laugh: :laugh: . i've got the kz 650 and a z1000.
here are some pics of them.



Post edited by: dixie789456, at: 2005/12/11 09:13

Welcome, Dixie.
Those are a couple of nice looking rides.

Too much of a change on front sprocket can be bad for chains. Wear could be excessive as it has to turn a small radius. That can cause your chain to wear prematurely and a worn chain will then wearout the rear sprocket. I don't like going down more than 1 on the front. Could get expensive.

I'm going to be changing my gear ratio soon too, but nothing that drastic. Stock is 16/38, I am going to go to 15/38 or 16/41

IIRC, Honda made a particular model that used a 530 chain and had a 13 tooth front sprocket, and I believe it was well known for destroying chains.

Maybe Z-doc will remember the model and chime in here

would a 14 or 15 tooth be better? or will the 14 tooth still be too small? i want what is best for the bike but still get neck snapping tire burning acceleration!!

Hey dixie-I put a 14 tooth on the front of my '77650 Custom and left the back stock at 42 (a brand new one along with new chain) I am very happy with the combination which I understand, gives about 12% better acceleration-all other factors being equal. This is according to an old racer friend of mine that has owned a Harlely/Honda shop for 25 years and he has forgotten more about performance than most will ever learn.

Along with the other mods I did, I am more than happy with my gearing choice and I have also retained a little top end pull for passing on the highway without revving the snot outta the motor.

My advice is go with the 14 and the 42. If this isn't enough low end grunt for you then drop another tooth on the front (front sprockets are a lot cheaper than the bigger rear ones.). Hopefully you will have enough adjustment in your chain to accomodate this mod without having to spring for another chain.


1977 KZ650 Custom. Brought back from the dead after 13 years of neglect. Totally rebuilt from frame up. Wiseco 700 kit. Ported, polished heads. Triple angle valve job. Properly re-jetted rebuilt carbs, Filters, MAC Pipe, Barnett Clutch, Shortened Signal Light Stalks, Sculpted Seat, Painted Speedo/Tach Collars and Brake Calipers, Recessed Licence Plate, Polished Headlight Bucket, Bridgestones, Bead blasted rims, 14 tooth sprocket front, Superbike Bars, Painted 2005 Chrysler Magnum Red with silver and gold stripes. Only 13,000 miles on bike. Runs and looks like new and does it ever jump off the line! Colin Firth-Ontario-Canada

steell wrote:

IIRC, Honda made a particular model that used a 530 chain and had a 13 tooth front sprocket, and I believe it was well known for destroying chains.

quote]

The first year CB 750 had a 13 tooth front sprocket. It was known for destroying chains and the sloppy chain would often come off and destroy the engine case.

Daniel

Better to go up on rear sprocket. What's more expensive a rear sprocket or broken engine cases, prematurely worn chain/rear sprocket,being stuck out in the middle of Butt F!@# nowhere, looking foolish when it snaps during a burnout/wheelie/testestrone show. One down on front (maybe two but I don't personally like) and go way way big on back.