Unofficial Royal Enfield Community Forum

Royal Enfield Motorcycles => Bullet with the UCE engine => Topic started by: Drifter on June 24, 2010, 08:56:45 pm

Title: Smaller Rear Sprocket on C5?
Post by: Drifter on June 24, 2010, 08:56:45 pm
Well it seems that you cant change the front sprocket to a larger size. So i was thinking just drop the rear 3 teeth and get the same result, NOT  Talked to the local dealer in frostproof yesterday and was told you can only go larger not smaller on the rear....if that is the case i guess all of those with a C5 are stuck with what they got.

 Not sure what if any logic was used in that decision just like the no kicker, seems rather stupid to me to build a chain drive bike and no option for taller gearing, maybe they thought they would never leave India. We in America and Europe need taller gearing!

Any idea why the chain was moved to the right side on the UCE?
Title: Re: Smaller Rear Sprocket on C5?
Post by: ace.cafe on June 24, 2010, 10:09:56 pm
You could change to 19" wheels.

My guess about the drive chain being moved to the right side, is that the brake actuator and linkage is on the side with the chain, and it eliminates the weakness of the cross-over bar in the brake pedal system which has been a hated thing for years.
Now, they actually have the  brake pedal on the same side as the brake  linkage, which makes for better braking, and no low-hanging brake pedal hanging down under the exhaust pipe.
Title: Re: Smaller Rear Sprocket on C5?
Post by: r80rt on June 24, 2010, 10:18:45 pm
Maybe we'll see a belt drive kit someday, that might offer gearing changes.
Title: Re: Smaller Rear Sprocket on C5?
Post by: singhg5 on June 24, 2010, 10:59:53 pm
............     Not sure what if any logic was used in that decision just like the no kicker, seems rather stupid to me to build a chain drive bike and no option for taller gearing, maybe they thought they would never leave India. We in America and Europe need taller gearing!

Hello Drifter:

RE has been selling old style 1950/60s carburetter Bullets in USA and Europe for many years.  They are history now.

If you look up the development of newer EFI UCE models (C5, G5 etc) which were introduced in 2009, there was a tremendous amount of input from USA importer, UK designer, Italian body maker and Japanese and Indian companies.  The result is what you see in current models.  I am quite sure that lots of brains with many years of experience in motorcycling and knowledge of international markets have created these well received models.

If someone wants a ninja, or kawamotosaki and buys an RE he will be surely disappointed.  If someone buys a Goldwing expecting it to be a great dirt bike, he will surely be disappointed too.  RE does its best what it is designed to do.  RE will not turn into a ninja or a Goldwing  ;).

WE in America and others in Europe happily ride regular size sprocket RE bikes and smile for what it is - It is much more than the speed that you expect from a smaller rear sprocket - because the whole system was designed and optimized with that sprocket size   ;D
Title: Re: Smaller Rear Sprocket on C5?
Post by: Drifter on June 25, 2010, 01:19:16 pm
I have a Ninja along with 9 other bikes, the point about gearing changes is many myself included would like the option of taller gearing for a more relaxed ride and safer speeds on American roads, better gas mileage and longer engine life.

I know of no other chain drive bike Including the 2 Brits i own that you can not alter the gearing. The standard gearing on the C5 seems to be for slower paved or dirt roads. Even 2 lanes around here people run 70+  so even 1 front or 3 rear would make a big change. The ability should have been designed into the new bike!
Title: Re: Smaller Rear Sprocket on C5?
Post by: 2bikebill on June 25, 2010, 03:40:47 pm
""The standard gearing on the C5 seems to be for slower paved or dirt roads.""

You got it in one.

""Even 2 lanes around here people run 70+ ""

Bullet's the wrong bike for 70+ - it aint that happy at freeway speeds. It does like doing around 60 on the old roads.
Title: Re: Smaller Rear Sprocket on C5?
Post by: Ducati Scotty on June 26, 2010, 02:43:33 pm
Maybe we'll see a belt drive kit someday, that might offer gearing changes.


Not likely.  Belts are far wider than chains and it's often hard to find the space to retrofit them.  Also, since you can't easily add and remove links to a belt the way you can with a chain, you have to consider the whole system of both gears and the distance between them on any given bike.  Lose or gain too many teeth on either side and you need a whole new belt size.  And the gears take a lot more machining to cut than chain gears, making them more expensive.

Also, for all their maintenance free advantages I think belts are less efficient than chains which means more power loss.  While most here consider the humble 500 single's output adequate, I don't think anyone would volunteer to toss horsepower away.

Lastly, do you realy think a belt drive would look at home on a vintage British single? ;)

Scott
Title: Re: Smaller Rear Sprocket on C5?
Post by: Ducati Scotty on June 26, 2010, 02:47:34 pm
I know of no other chain drive bike Including the 2 Brits i own that you can not alter the gearing.

There are often limits high and low to what you can do to the front sprocket due to space.  On the rear, I don't know if there's a space issue but the sprocket is specially made to mate up to a hub.  You can take the rear wheel completely out of the bike and the sprocket stays behind.  This leads me to believe that it's not a stock part that fits anything else.  If you wanted to get some machining done I'm sure you could adapt another sprocket to the rear end of an Enfield but it seems at least for now that no one offers them off the shelf.

Scott
Title: Re: Smaller Rear Sprocket on C5?
Post by: ace.cafe on June 26, 2010, 04:23:57 pm
There are often limits high and low to what you can do to the front sprocket due to space.  On the rear, I don't know if there's a space issue but the sprocket is specially made to mate up to a hub.  You can take the rear wheel completely out of the bike and the sprocket stays behind.  This leads me to believe that it's not a stock part that fits anything else.  If you wanted to get some machining done I'm sure you could adapt another sprocket to the rear end of an Enfield but it seems at least for now that no one offers them off the shelf.

Scott

On Bullets, the rear "sprocket" is a set of teeth machined onto the perimeter of the brake drum. There is no separate "sprocket".

To get a separate sprocket arrangement, you have to put a different hub on there, from some other kind of bike.
Title: Re: Smaller Rear Sprocket on C5?
Post by: The Garbone on June 26, 2010, 05:31:44 pm
Eh,,  CMW sells an aftermarket rear sprocket that you can put different counts on. Thinking its roughly $200.   I am at work so I don't know if it fits the new UCE bikes but I imagine it will.   

They need to make a pocket catalog so we can quick reference these things,  weather that part has a diamond and spade next to it or not...
Title: Re: Smaller Rear Sprocket on C5?
Post by: ace.cafe on June 26, 2010, 06:27:17 pm
Eh,,  CMW sells an aftermarket rear sprocket that you can put different counts on. Thinking its roughly $200.   I am at work so I don't know if it fits the new UCE bikes but I imagine it will.  

They need to make a pocket catalog so we can quick reference these things,  weather that part has a diamond and spade next to it or not...

With the CMW aftermarket sprocket kit, you can only go larger with the add-on spockets. Not smaller.
The brake drum O.D. is the limiting factor in going smaller.
That kit could be nice for dirt bikes or applications where you want to use larger  sprockets, though.
Title: Re: Smaller Rear Sprocket on C5?
Post by: Ducati Scotty on June 27, 2010, 11:01:47 am
So when the original rear sprocket wears do you just replace the entire hub?

Scott
Title: Re: Smaller Rear Sprocket on C5?
Post by: ace.cafe on June 27, 2010, 01:06:13 pm
So when the original rear sprocket wears do you just replace the entire hub?

Scott

No, just the brake drum. The brake drum is removable from the hub.
The sprocket teeth are actually machined on the outer rim of the brake drum itself.
I know it's unusual compared to other bikes, but that's what the situation is.

That's why everybody always changes the front sprocket on Bullets to make gearing taller. It's a pain in the butt, too.
The UCE  restricted front sprocket clearance is a limiting factor, then. But it appears to be easier to change the UCE front sprocket, than it is on the Iron Barrel models.

However, due to the low power of these bikes, they need to be relatively high up in the "powerband"(if you could call it that), to produce enough hp to overcome the wind resistance at higher speeds. If you lower the rpms, then you have to widen the throttle opening position to make more torque at the lower rpms, so that you have enough hp. So, the supposed "benefits" of "improved fuel economy" and "lower engine wear" become dubious.
In most cases with Bullets, 18T front sprocket will give best results because otherwise it starts getting over-geared too much for a stock bike. By "over-geared", I mean it can't reach redline in top gear because of not enough power with that gearing.

When people make the move to a Bullet from larger displacement bikes, sometimes it is a surprise to feel the bike riding at higher rpms on highway cruising.  You need to be making nearly 3/4 of your total available hp to just do 70mph. It's not so much the gearing limitation, as it is the power limitation. It tops-out around 80mph, and not because of under-gearing.  The little hamsters are running in that exercise wheel almost as fast as they can go. :D
The UCE only makes about 21.4hp max at the rear wheel. The advertised 27hp is hp at the crank. Rear-wheel dyno tests show about 21.4 at the wheel.
And on top of that, if you use taller gearing, it reduces the torque-multiplier of the gear ratio, and that further cuts actual power to the road at the rear wheel. We don't have much power to "burn" with losing torque-multiplier in gearing changes.
Title: Re: Smaller Rear Sprocket on C5?
Post by: Drifter on June 27, 2010, 01:43:39 pm
 Any motorcycle can pull a 1 tooth higher front sprocket the C5 can for sure. I have changed gearing on 90% of the bikes i have ever owned from large cruisers to 80cc 2 strokes and none had any problem pulling the gearing.

Its not uncommon for a motorcycle to reach higher speeds in a lower gear like 5th on a 6 speed bike due to a high overdrive top gear, that has little to due with the engines ability to use the overdrive or higher gearing.Many cars and trucks will run faster top speeds out of overdrive. Case in point i changed the gearing on a Kawasaki 500 Ninja the max available which was 2 higher on the front and 9 lower on the rear a massive change!!  The bike ran fine at 65-70 in 6th but it would not pull redline in 6th so a downshift to 5th and WFO indicated 132 MPH on a stock 500 cc bike. 

The point im making is if this bike could easily handle a massive change a UCE would have NO problem with 1 tooth. My AR 80 pulls 2 larger on the front and it will do an indicated 75 Mph with 80cc in 6th with the taller gearing,
Title: Re: Smaller Rear Sprocket on C5?
Post by: ace.cafe on June 27, 2010, 02:27:50 pm
I''m sure it could pull another tooth, if there was some way to get one in there.

I didn't mean to divert the thread with technical stuff.
If you want one, then I think you should be able to have it.

However, given the need to modify the crankcase and have sprockets made, probably the easiest route would be to use the larger wheels and tires.
Title: Re: Smaller Rear Sprocket on C5?
Post by: Drifter on June 27, 2010, 04:57:56 pm
Ace, i agree the easiest way it seems is to change wheel and tire size.
Title: Re: Smaller Rear Sprocket on C5?
Post by: Ducati Scotty on June 29, 2010, 04:30:28 am
So a little thread jacking here now that my curiosity is piqued...
1) How often do you need to change the rear sprocket/drum because the sprocket wore out?  How expensive is the part? 
2) On the new UCE bikes can you still remove the rear wheel and tire without taking off the chain?

Scott
Title: Re: Smaller Rear Sprocket on C5?
Post by: SSR on June 29, 2010, 02:06:49 pm
So a little thread jacking here now that my curiosity is piqued...
1) How often do you need to change the rear sprocket/drum because the sprocket wore out?  How expensive is the part? 
2) On the new UCE bikes can you still remove the rear wheel and tire without taking off the chain?

Scott

Rear sprocket is usually changed alongside the chain and front sprocket. Depends how well you have looked after the chain. So far what I have heard is that the set can last up to 10-12kmiles but some have reported twice the lifetime in CI bullets. Dont know about the price.

Removal of the rim/tyre is still the old style without touching the chain and pads.
Title: Re: Smaller Rear Sprocket on C5?
Post by: Ducati Scotty on June 29, 2010, 09:18:00 pm
That's the mileage I expected/feared. RE parts are generally affordable so this probably doesn't cost too much.

I guess this was one of their innovations like swingarms suspension, maybe it just didn't work out as well.  Still nice to be able to remove the wheel but leave the chain in place.

Scott
Title: Re: Smaller Rear Sprocket on C5?
Post by: Ducati Scotty on July 04, 2010, 05:38:26 pm
Just poking around the parts site, saw this:
http://store.royalenfieldusa.com/maintenance-repair/driveline/chain-and-sprocket-overhaul-kit

Not a bad price for all the bits I suppose.

Scott
Title: Re: Smaller Rear Sprocket on C5?
Post by: Ice on July 04, 2010, 06:09:21 pm
 I should think with careful and regular maintenance a street ridden Bullet should get more than 12,000 miles out of a chain set.
 
Title: Re: Smaller Rear Sprocket on C5?
Post by: Ducati Scotty on July 04, 2010, 06:26:58 pm
Good to know.  Do some people replace the front sprocket while keeping the same rear and chain?  Just trying to gauge maintenance before I buy.

Scott