Final Drive Swap Poll

[cywelchjr]

This crap about the same amount of energy being expended to go the same distance no matter what the gearing is just that, crap. Try going 150 miles in 1st gear. The do it in 5th gear. You won't use the same amount of gas. Now, it's true that once you get to the a certain point it is true that you will get no more efficiency once you hit the sweet spot, but frankly, these bikes IMHO and from what's being seen for the most part, don't hit that with stock gearing, they are just a bit short of it, so the swap does give just a LITTLE boost in economy for many. That is why frankly they put 6 speed trannys in new cars with overdrive trannys these days, and if it didn't make a difference, they wouldn't have done it, they wouldn't have spent the money doing it. If you gear a vehicle for speed, it's not going to get the same gas mileage as one geared for freeway driving/cruising. This is of course why I'll agree this mod is not for everyone, but those that haven't at least ridden one with the mod should not dismiss it with such disdain. It's like taking an old muscle car with 4:11 gears vs one with 2:11 gears. The 4:11 gears will tear up the 1/4 track, but get bad mileage, the 2:11 will get much better mileage, but won't do so well on the track, but will be a much better road trip car. Then along came overdrive 5 and 6 speed trannys, which let you have the 4:11 track times with 2:11 economy. We can't quite have that, we have to to some degree make a choice, although I'll admit, it's not really as big a difference for us.

[Bonz]

Looks like this poll has about run it's course...

Thanks guys for all the discussion. I'm loving my FD swap, it's the right ticket for me and my 80 SG.

[James England]

Looks like this poll has about run it's course...

Thanks guys for all the discussion. I'm loving my FD swap, it's the right ticket for me and my 80 SG.

Yep. I love mine too

[Mendizale]

Hi folks,

I'm hopping on this thread with a related question--from reading through the posts, it seems like you lot are the ones to ask.

I recently bought my Special, under the impression that it was OEM (though I'm not sure I care). Some posts have said that the Standard gets to about 5200 RPM at 75 mph, and that the Specials may even run higher. I haven't run mine at freeway speeds much yet, but I tested it today and got to about 4900 to 5000 on flats or slight uphill. In your opinions (this thread seems strong on opinions and evidence), might my final drive be converted already? How might I tell?

Many thanks,

Mendi


PS: interesting discussion...

[CatatonicBug]

What speed were you going on those flats? Generally, you'll see about an 800rpm drop at 70mph with the switch to the 750/850 FD. I'd say that if you were going 60-65 mph at 4900-5000rpm, you still have the stock FD. You can always pull the rear wheel and take it off to check.

[bikerphil]

If you shine a flashlight thru the spokes of the rear wheel from the right side of the bike, you can see the ID number on the top inboard side of the final drive. 2H700 is the number for the stock 11 drive, 1J7Y0 is the number for the 750/850 drive.

[Mendizale]

What speed were you going on those flats?

I was averaging 73-77 mph, I should think.

I'll look at that final drive number soon, bikerphil.

[jetmechmarty]

My bike is stock. At 3500 RPM, I'm traveling at 55 MPH. 4K @ 60 5K is around 70.
FWIW, my stock XS650 is geared very close to the same.

[Bonz]

Here's what I have to share... Stock with my Special at an indicated 75 mph, I was turning 5200 rpm, with the FD swap I am turning 4700 rpm. I used a GPS to check the accuracy of my speedo last week, and at an actual (GPS) 75 mph, I'm turning 4500 rpm after the swap (which would equal 5000 rpm at a GPS 75mph with the stock FD). To simplify the confusion over what I just said, my 80 Special is actually running 78 mph at an indicated 75, and an indicated 60 mph is actually 62 mph.

I don't know of a Standard with a close to properly functioning tach or speedo could be doing 5200 at an indicated 75 mph, IMO. At 60 mph, the Standard should turn 200 or so less rpm than the Special, and the rpm difference would be even greater at 75 mph.

If your speedo is accurate, then 5000 rpm at 75 mph is right where a stock Special should be.

BUT....

With that said, bikerphil shared the unequivocal way to tell by looking at the ID number. Thanks for sharing that bikerphil!

[bikerphil]

Hbonser, no problem. One thing I might add about the 850 (gen 2) final drives. I run those in both my Standard and Special and I've blown the front seals out on both of them. I don't know if it's coincidence, but I've never blown one out on a stock 11 drive before.

[Bonz]

bikerphil,

I assume the 850 and the 750 FD could be susceptible to what you said, not just the 850, corrrect?

I honestly can't remember if I have an 850 or 750 FD, I bought it already converted from papanovember here on the forum, so I had a really easy plug and play, but I knew when I bought it which one it was. I'm only 43 but CRS is taking hold!

I haven't heard of any seal blow outs on the FD conversion other than yours, but maybe it's happening more than we know, and simply not being stated? Interesting...

[Mendizale]

The results of hbonsers's impressive calculations are reinforced by the "2H700" graven on the final drive.

If only I had beautifully printed and bound owner's/shop manuals, I might not have to bug you guys every two seconds... (hint hint, catatonic...).

[Bonz]

No problem, it ain't a bother at all... Keep up the search for knowledge!

[James England]

My OEM FD has the word YAMAHA in raised lettering under the axle hole. Letters about 1" big. On my XS750 FD, I noticed there isn't the word Yamaha. I don't know if Yamaha is on all the FD's for all the different models but it's certainly on all UK ones.

[Bonz]

Just can't let one of my all-time favorite threads sit idle for TOO long...

Man, the 80 SG is running so nicely with the FD swap. The sweet spot is about 4500-4700 rpm where the bike just feels right, whereas I really never ran the bike in that range on the Interstate before, as I was turning around 5000-5200 rpm with the stock FD at the same speeds (around 75 mph).

In the overall picture, it is interesting to see how many more Standards had the FD swap done vs. the Specials. I would have thought it was 50-50 or even a bit shaded to the Special side. And that there was just one rider that changed back after giving it a try.

Looking forward to the Southwest Rally in Durango over the 4th of July weekend and getting a proper road trip under the SG's belt with the swapped final drive, Plexi III windscreen and soft luggage purchased recently.