It's winter and thought a little bar stool chat and questions would be interesting and informative

I'm curious about the real differences between having an 883 with a 1200 or 1250 kit. Let's assume for this question the bike is an EFI US bike. Let us also assume it's a basic conversion using the stock 883 heads. Also the air filter, pipes and a good tuning are all equal.

What are the quantifiable differences between using the 883 gear and the 1200 gear?

It makes sense that acceleration off the line will be better with the 883 gearing. But by how much? Has anyone ever compared what the two with 0-60 and 1/4 mile times?

It's also safe to guess that 5th gear passing from 60 to 70 mph will benefit the 883 gearing. But how much?

I would think that at higher RPM the 1200 gearing takes over where the 883 gives out. This will effect, among other things, top speed. Which the 1200 has the edge. I'd guess by about 7-10 mph but I have no hard facts.

Obviously the 1200 gearing lowers RPMs at highway cruising. By a few hundred RPM depending on the gear and speed.

My main question is; how much does the 1200 gearing effect acceleration compared to the 883 gearing? I'd like to see hard numbers and not just subjective guessing based on someone's *** dyno. lol

Any ideas?

Thanks all!

 

883 has a 24 tooth front sprocket. 1200's have a 28 tooth. XR1200's use the 24 tooth.

Either is okay. However the XR goes to 9K rpm so top speed is 125 mph. Never did the 1/4 times on either or top speed on the Low.

I plan to get a 24 tooth for my 11 XL1200L for more pick up and it will be smoother at highway speeds. To me the 28 tooth is too tall.

There is a 26 tooth available.

The Low at 55 to 65 with the 28 tooth just shakes a lot. It likes at least 70. but Illinois roads are 55 mph limit. The XR is smooth at 55 - 60.

 

Here are the two charts that show the difference in gearing as it relates to speed/rpm

If you are cruising at 80mph, the RPM difference is about 600. Pretty significant.

As you know I have the NRHS 1250 kit in my 883. I have done a bit of "abandoned street" racing with Devin on his Dyna. We had to use rolling starts. Reason being, I am not skilled enough to accelerate fast from a stop without the back tire breaking (sideways sometimes) loose and/or the front end coming up more than I was comfortable with. (I am too old to loop a bike on the asphalt...lol, or the dirt for that matter)

Even at 10-15 mph rolling starts, when I hammer the throttle the back tire spins and the front wheel comes up. 2nd gear same thing, and sometimes in 3rd too.

I am seriously considering changing my gearing to get it closer to the 1200 stock gearing. I don't think I will miss any of the felt power, my rear tire will last longer, and I will increase my MPG while on the interstate.

 

Depends on which year bike! My 2011 883 has a 34T front, 1200s of the same year have a 38T.

As for which gearing to use, bear in mind that recent bikes all have high gearing, to help them meet EPA regulations. So if we were to turn the clock back and optimise gearing, our bikes would have lower gearing than at present.

Changing gearing from 34T to 38T will reduce torque at the rear wheel by approx 12%, also lower engine revs at any road speed by the same amount. It could be said that changing gear will take away 12% of the good work the upgrade gave!

 

Here are the charts that will give everyone and idea as to the RPM differences. This will probably be a little different depending on the year of the bike. Yet it's solid ground to pick from.*

As can be seen, there is a significant difference in RPM at 70 mph between the two gearings. Which, to me, can be worth while on the highway. Yet, there are no charts showing the difference on how that effects acceleration.*

Obviously if one is trying to build an all out torque monster, a drag strip bike or wants to get the highest dyno numbers than the 883 gearing is the way to go. However, the vast majority of those that do a 1200/1250 conversion only do a basic one.*

I just haven't seen evidence that going with the 1200 gearing will be negatively effected to such an extent that it wouldn't be worth doing. Especially for average daily use.*

The power increase going from the 883 to the 1250/1250 will not be completely wiped out by moving from the 883 pulley to the 1200. The notion that it would is misleading. *

I'd just like to see the acceleration numbers.*

 

I love kick *** acceleration, usually experience it at least once on every ride (makes me grin all over) whereas top speed I have only experienced once since I purchased the bike a couple of years ago when my son decided he was going to beat me home.

 

Having recently gone from an '05 883 to an '05 1200 I can tell you I have the 1200 gearing. Seems like I have no need for 4th or 5th most of the time. I may end up gearing down my 1200 if I can.t get used to it once riding season starts again.

 

I can't remember what year the 883 got the 29T belt sprocket - same as the 1200. On prior years, the rubbermounts had a 28T. International bikes got a 30T. One tooth affects your RPM by about 3.5%.

The primary sprocket on the 883 is 34T, on the 1200 it's 38T. This is a difference of about 10%.

On my 1200 conversion, with the 883 primary and the 28T, I found first gear almost useless. I think if you're into burnouts and barhopping, it's probably fun to have that gearing. For highway driving, not so much.

I changed both the primary to 38T and the belt to a 30T international. Now my bike is great on the highway. At 70ish I was running 4000 RPM, now I'm down to something like 3250. HUGE difference on a trip.

And with the extra torque from the 1200/1250, first gear has plenty of jam around the city.

 

I can remember back in the 80s when Alfa Romeo improved a car's 0-60 performance by RAISING the gearing.
Shifting 1 less time made the difference.
Many vehicles also have a lower top speed in top gear than in the 1 below.

 

You're going to be hard pressed to find solid accel numbers. Motorcycle magazines and reviews click off a half second worth of ranges in 0-60 times for non-sport bikes. People don't buy cruisers because they're focused on 0-60.

That being said, the difference will be noticeable if you ride them back to back or ride one every day and jump to the other, otherwise you won't notice much unless you're paying attention (closely) to speed at redline. The biggest thing you'll notice is how wound up (or not) the bike is at particular speeds in particular gears (ie. 5th on the highway, or 4th at 45 in town). Though running through the gears WOT you most likely won't notice a whole lot unless a WOT drag run is a daily event for you.

If I was going with the NRHS kit I would most likely push the front sprocket up a bit to lower the ratios overall (lower revs). The main reason being that the 883 might be a bit too wound up and 5th gear on the highway is wound up enough stock. Not sure if it's necessary to push the ratios down to the point where it's similar to a 1200, though you can if you want.

Best bet is to throw a front sprocket on and see what happens.

You can't say whether it "is" or "isn't" worth it. Some people prefer tighter gearing, some don't. That's very preferential.

Sprocket is easy to change, wait until the 1250 kit is on there, then worry about the gearing. For all you know you may love it with the 883 gearing, so there's no point to lowering the ratios at all! .