rz350 gearing

[yamasukiman]

I have a rd350lc with a ypvs motor fitted.The bike also has rz wheels and sprockets.
It's an rz250 motor with rz350 topend.
It turn's an indicated 80kph at just under 5000rpm and this seems way too short.
What does a stock rz350 turn at 80 kph?
Any help will be appreciated.

[Sprint]

Paging g0zer...

S.

[g0zer]

im pretty sure the rz250 and rz350 are geared different, in the gearbox and front sprocket.

i run an 18 tooth front and 40 tooth rear with an rz250 gearbox/bottom end which gives me something like 190km/h at 10,000rpm with a vmax around 200km/h on over-rev so it could probably take a slightly higher gearing perhaps 18/39 or 18/38 depending on how strong your motor is.

im running rgv wheels tho which wont be the same diameter as yours.

easiest way to figure it is take your bike to 10000rpm in 6th gear and measure your speed with a GPS, then recalculate your sprocket ratio's for 190 to 200km/h at redline.

edit: you could do the same thing by measuring speed in 6th at a lower rpm as well i suppose

[Richie Rich]

RZ250 / 350 gearbox (in fact whole bottom end) is identical but as g0zer says likely to be different in the final drive sprockets (250 will be geared lower).

My 350 runs an extra 4 teeth on the rear sprocket as I reckon they're overgeared as STD. This gives about 6000 @ 110 km/h - and about 190 top end. From memory STD gearing is about 5000 @ 100...

Google search 'gearing commander' - great little site that has lots of gearbox ratios for many different bikes uploaded - incl the RZ - and allows you to see what effect playing with the sprocket sizes has on the final gearing - revs and speed. I used it to choose my gearing and it works a treat.

[yamasukiman]

Thanks guys,
I figured it should turn "about" 100kph at 5000rpm and what you have both said is about ball park.
I'll need to see that the speedo is correct as 80kph feels a bit fast by the seat of my pants.
I did not know that rz250/350 bottom ends were the same as far as crank to clutch ratios go! and gearboxes.
The aircooled rd250 and rd400's use a different crank to clutch drive ratio.
Thanks for the info.

[yamasukiman]

I just used that gearing commander Richie Rich, brilliant!
Thanks for that.

[Richie Rich]

I just used that gearing commander Richie Rich, brilliant!
Thanks for that.

No worries mate, it's incredibly handy - forgot to add in the post that it will even calculate gearing changes from tyre size changes. Good luck with your bike, post some pics when you get a chance!

[yamasukiman]

I'm not sure how to post photos!

[D.J]

hey Ian, upload to photobucket or similar and copy the photo link in the box after you click the insert image icon (little square picture frame thinky). clear as mud?

[yamasukiman]

Did it work?

[yamasukiman]

[D.J]

looks like your missing the rest of the link

[yamasukiman]

Third time lucky!

[D.J]

Third time lucky!

still must be missing part of it, on photobucket you should be able to click on the direct linke this VV



just put the cursor over the picture and it will bring up the box with direct link in it, then click in the direct link box and it will automatically copy, then you can paste into the psb link.

hope this helps mate.

[yamasukiman]

one more try!
Thanks all your help DJ.

[yamasukiman]

Last try!

[Richie Rich]

Email me the photos mate and I'll post them up - richmbc@hotmail.com