Passing Gear?

[motoman]

There would also be a difference if the 750 or 850 final drive was installed of like 700 RPM also at this speed. So who is running what rear end is very important too.

Original stock final drive, Continental Go tires on both ends that are new. Conti's DO run a bit wider and taller to comparable size other brands. At 75mph, lost 259-399rpm. The Venturer having 17in. rear NOW runs dead-on 5,000rpm at 75mph. BTW,stock final drive that's NEVER been removed as that is why 30pumps os the standard grease gun is done every other oil change. Also, the rear Conti Go has .015 clearance from driveshaft tube.

[Bigfoot]

If the ratios hold true, using 58 as a median, we could say that at 80 mph, we would be turning ( 80 X 58 ) 4640, and we would be doing about 85 at 5 grand.
Hooo boy, are we having fun yet?

CZ

So, with your final drive swap, you are seeing around a 400 rpm difference as compared to my stock setup.

Hmmmm, isn't that about the difference Tod has been saying it would make all along?

[red bandit]

Yepper.... At 60-70 it's about 400 difference at 100 it's about 800 difference.

[motoman]

Yepper.... At 60-70 it's about 400 difference at 100 it's about 800 difference.

Sorry, but ain't happeneing my friend..........400rpm loss IS gonna be constant thru ALL speed ranges..

[Bonz]

In a direct drive system with a non-slipping clutch, if the bike is 400 rpm lower at "60-70" mph, then the bike would have an 800 rpm difference at "120-140" mph. True story, in fact. Just as if a bike is doing 4000 rpm at 60 mph in 5th gear, it would be doing 8000 rpm at 120 mph in 5th gear.

It doesn't matter WHAT the tach says, that is a 35+ year old device reading rpm, and reporting back that a bike does "this, that or the other" is a moot point. Gearing rules are what they are and non-negotiable with respect to variance that is being posted here.

You guys need to trust math and quit the debate!

[Bigfoot]

Look at Bonz whipping out the logic on us.

[Bonz]

Yep! Love the logic of math. .

[trbig]

Bonz, you're wrong! Mama said that just slapping on the 850 final drive will reduce your idle by 800 rpm!

Oh.. and H2O is GOOD!

[red bandit]

Yep, the numbers don't add up. Should have put that in my post. Was typing from my notes with out brain engaged. That's my story and I'm sticking to it. But now I wonder what is my actual rpm when the tach says 8K.

[trbig]

Little digital rpm meters are cheap if you don't trust your bike's tach.

[XJOK2PLAY]

Bonz, you're wrong! Mama said that just slapping on the 850 final drive will reduce your idle by 800 rpm!

Oh.. and H2O is GOOD!

"... and mama is wrong again!"

"... No, Colonel Sanders! You're wrong, and Mama's right!"

Hehehe.....

[Bonz]

Period tests when tachs were working and gear ratios not in dispute had the Special running 3943 rpm at 60 mph and the Standard turnng 3790 rpm. 150 rpm difference between the two for practical purposes.

When I owned an 80G (stock FD) and the 80SG (FD Mod) at the same time, the G felt a bit quicker because the gearing of the SG (FD mod) was taller than the G (stock FD). Interesting though, both bikes were SO similar in feel, I would have a hard time telling them apart blindfolded in terms of shifting, engine vibration (lack there-of), etc. Yamaha made a winner in either one!

Personally, I would not have done an FD mod on the G had I kept the bike. It felt "right" vs the SG that always felt "too busy" with the stock FD when running 75-80 mph on the interstate and 60-70 mph on open back roads for extended periods.