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Author Topic: Why retain a primary chain drive on a UCE.  (Read 1882 times)

chinoy

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Why retain a primary chain drive on a UCE.
« on: January 09, 2010, 11:28:53 AM »
Im just wondering what was the logic in retaining the primary chain drive.
If your anyway moving to a UCE design.

Why didnt they just drive the Clutch basket off the primary gear like 99% of all motor cycles do.

What would it take to dump the Primary chian.
A larger Primary gear with a larger gear behind the Clutch basket ?

t120rbullet

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Re: Why retain a primary chain drive on a UCE.
« Reply #1 on: January 09, 2010, 11:45:23 AM »

Why didnt they just drive the Clutch basket off the primary gear like 99% of all motor cycles do.


Gotta leave something for the 1% that's left.
CJ
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2012 Concours 14 (no name yet)
2013 Royal Star Venture S  "Jelly Roll"

ace.cafe

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Re: Why retain a primary chain drive on a UCE.
« Reply #2 on: January 09, 2010, 01:02:53 PM »
I don't know the specific reason why they did that.

However, I can say that with the chain drive, both sprockets would turn in the same direction, while 2 meshed gears would result in the transmission turning in the opposite direction.
Home of the ACE Fireball 535 Bullet,  Ace GP Hi-Lift Roller Rocker Head . Pistons, cams, etc. Highest performance Bullet engine mods available .  AVL mods. Redditch 700/750 Twin mods. UCE kit soon.

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Vince

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Re: Why retain a primary chain drive on a UCE.
« Reply #3 on: January 09, 2010, 10:36:12 PM »
     The specific reason is the style of the transmission. The British design  is a lay shaft transmission. In a more common counter shaft transmission power is transmitted to a main shaft which drives the output or counter shaft. This gives the opposite turning Ace mentioned. In a lay shaft transmission the main shaft is also the output shaft. The gearing is set up to go through the other shaft in the transmission, but drives back to the main shaft. To run primary gears would require the engine to run backwards from it's current direction so as to drive the main shaft to drive the bike forward.
     Another consideration is the size of the crankshaft. It's size requires that the transmission be fairly far back in the cases. The gears required to eliminate the primary chain would have to be huge to span the distance between the crank and main shaft centers.
     In short, to eliminate the primary chain would require an engine redesign that would make it not an Enfield. It would lose all the qualities that we hold dear.

motocamp

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Re: Why retain a primary chain drive on a UCE.
« Reply #4 on: January 10, 2010, 04:19:50 AM »
well said Vince , probably why Harleys still retain their primary drive chain.

Gotta leave something for the 1% that's left.
CJ


I agree , some things are just about heritage vs modern design.


Chasfield

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Re: Why retain a primary chain drive on a UCE.
« Reply #5 on: January 10, 2010, 05:11:35 PM »
A geared drive would probably have required more complex machining of helically cut gears. Easy to make, straight-cut ones would be too noisy outside of a race track. A geared primary drive of any sort would have added  a japanese-bike-esque whine to your Bullet , which may not have been  to everybody's taste.

Also, enclosed primary chain drives are efficient and have some inherent drive-line cushioning qualities that are absent from geared ones.
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chinoy

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Re: Why retain a primary chain drive on a UCE.
« Reply #6 on: January 11, 2010, 10:06:34 AM »
Thanks for explaining it so well.

The UCE engine was designed from scratch to be totally different.
So I dont see the logic in not fixing this.

The reasons I see really dont hold any water.

a. More efficient ?  Come on boss. Its not efficent from any angle. You can look for a few plus points but the negatives out weigh them 10:1. Which is why the rest of the world has moved on.

b. Because its classic and we love classic ? What part of the UCE has anyting to do with clasic design or british design ? From which angle. ? Its an EFI modern engine.
Want to modernize it then go the whole hog. When they where designing the bike they could have sorted out the issue.
Thanks to your points I see its a lot more complex than I initally thought.
But Im still going to think about it.
What if you added a gear between both That would take care of your direction issue right ?


c. Straight cut gears ? In the 60s and early 70s you had bikes like the RD350 with this system. So its not a new idea. The TZs ran straight cut but the RD / Banshee / LC all ran angled gears with no problems.

d. Because the Harleys do it is one of the worst arguments to have lol.
Sorry Just don't get the Harley Trip. Never have never will.

But seeing as there is no easy fix at this point no point disusing it.
The fact that they still had the chain in there was a rude shock to me.
Somebody had told me it was direct drive. Which was obviously wrong info.


Geirskogul

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Re: Why retain a primary chain drive on a UCE.
« Reply #7 on: January 11, 2010, 05:39:09 PM »
A chain adds cushioning to the drive system, and gives some allowance for vibration and shock.  Plus, with a proper primary chain system, it should/will last forever and need no attention from you.

I have a timing chain in my car that has lasted 130,000 miles, and would have probably lasted another 130,000 miles with no maintenance because it is constantly bathed in oil.  The "dry" primaries don't last too long, but this isn't one of them.  It's a submerged one.

A big, BIG consideration with the new UCE engine was with traditional look and feel.  In Royal Enfield's home market, India, a huge amount of attention is paid to look and sound, and  if the new engine didn't have a primary cover, or they put the starter in a different spot instead of making it look like a distributor, then I guarantee you it wouldn't sell nearly as well when they bring it out.

If you want a Japanese-style bike, then go buy a Japanese bike.  There's nothing wrong with them.  Royal Enfield is a niche product.  Niche products don't have to make sense.
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Chasfield

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Re: Why retain a primary chain drive on a UCE.
« Reply #8 on: January 11, 2010, 06:35:08 PM »
The other thing I thought of was crankshaft throw. The UCE retains a long stroke, and therefore, a large diameter flywheel.  This assembly necessarily displaces the gearbox back some way. It might not have then been feasible to get primary gears of sufficient diameter to mesh that didn't also make the outer primary covers look weird - like a drain cover.

With a short stroke Japanese four, the clutch basket can snuggle up close to the crankshaft sprocket and mesh directly with it.
« Last Edit: January 11, 2010, 06:39:01 PM by Chasfield »
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ace.cafe

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Re: Why retain a primary chain drive on a UCE.
« Reply #9 on: January 11, 2010, 08:08:29 PM »
The use of a chain is dictated most of the time, by the need to span a distance with the power transmission system.
With the information above about the layshaft transmission, and the distance required to place the transmission because of flywheel size, it seems logical to use a chain.

From an efficiency of power transmission view, the chain is as good as direct drive spur gears or a belt. In a proper environment a chain is 98% efficient in power transmission.
There is no gain to be had in efficiency by using gears. In fact, if quiet helical gears are used, they are less efficient than a chain, due to side thrust. And if a gear train of multiple gears(more than 2) is used, that is even further less efficient than a chain.

The main gain for using a pair of gears, if the layout allows it, is to make a compact arrangement. Slightly reduced weight in the cases, and no chain weight.
So, I really don't see that there is something "inherently wrong" with them using a chain in this application in the primary with the design of this powerplant. It's probably the best choice. To use a gear train to span the distance would be a net power loss.

I don't think that the Japanese would select gears to run the primary in an application like the UCE. There's a distance to span, a drive direction to be maintained, and it's a  low-revving application with chain speeds within the parameters where a chain can work, and the efficiency level is high.
« Last Edit: January 11, 2010, 08:18:27 PM by ace.cafe »
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cyrusb

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Re: Why retain a primary chain drive on a UCE.
« Reply #10 on: January 11, 2010, 09:03:28 PM »
It was cheaper. There are only 2 reasons anything happens in this world,Love or Money. As Vince said, they allready had a tranny that turned the right way. Using gears would have made them go for a new counter rotating tranny.

Chasfield

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Re: Why retain a primary chain drive on a UCE.
« Reply #11 on: January 12, 2010, 05:25:37 PM »
The Honda CBX makes an interesting comparison. This has a primary chain, despite being a short stroke, modern (well for an old boy like me)  design. It runs back from the centre of the crank.

Some exploded diagrams here:

http://www.cbxclub.com/davespage/cm&m_v54-2.html

I am guessing that Honda wanted a central power take off to minimise crankshaft twisting problems, and that requirement put the the clutch basket out of the equation

So a chain drive was the logical answer. Mind, changing that sucker is a big job!

Iconic bikes, those are - and getting expensive in the UK.

2001 500 Bullet Deluxe

motocamp

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Re: Why retain a primary chain drive on a UCE.
« Reply #12 on: January 13, 2010, 03:42:45 PM »
Don't feel cheated Chinoy  ;D, this is not a modern Jap bike EFI or not, like you said in one of your posts some where else you now have the best of both world's ,dont bother about it not being gear driven the chain drive  run's just fine...actually a lot of us like it this way.

If you think about it why OHV and not OHC or DOHC?? 

The answer-it is not a totally modern bike that is part of the charm, the main reason they shifted to EFI is becuse of the Emissions norms becoming more stringent.

Ride it a little longer open your mind, try not to be a speed junky you will get it. 



 

ace.cafe

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Re: Why retain a primary chain drive on a UCE.
« Reply #13 on: January 13, 2010, 04:18:11 PM »
Don't feel cheated Chinoy  ;D, this is not a modern Jap bike EFI or not, like you said in one of your posts some where else you now have the best of both world's ,dont bother about it not being gear driven the chain drive  run's just fine...actually a lot of us like it this way.

If you think about it why OHV and not OHC or DOHC??  

The answer-it is not a totally modern bike that is part of the charm, the main reason they shifted to EFI is becuse of the Emissions norms becoming more stringent.

Ride it a little longer open your mind, try not to be a speed junky you will get it.  



 

You make a good point, and I often see posts on Enfield forums, with people wondering why RE didn't make a 4-valve OHC engine with the new effort.

And yes, a good part of it is the desire to retain the long stroke design, which is part of what defines a Bullet.

With the long stroke design, max rpms are limited by piston speeds, to a lower max rpm than we see with some other modern hi-revving engines that have shorter strokes.
The advantages of OHC and 4-valve design are primarily seen in higher rpm engines.
Actually, a good 2-valve engine will outperform a 4-valve design up to about 4000-5000 rpms. The only way around that is to use VVT(variable valve timing) which adds alot of complexity and cost. And if we're only going to rev to 5000rpm anyway, what is the benefit? Pretty much none, actually.

OHC is a valve actuation system that works to keep the valves under better control at higher rpms. But, we don't rev to higher rpms, and pushrods do the job perfectly well at the rpms we ride. OHC just increases cost, makes the engine a taller package that may not fit as well into the frame location, and gives us no real benefit.

What happens is that people see certain technologies being used on other motorcycles, which they regard highly, and ask, "Why can't the RE be like that?".
And the real answer is that the RE is a different design, which doesn't benefit significantly from those kinds of technologies, because it is a low-revving engine, sort of like a Harley Davidson.
In our engine, with its rev range, pushrods and 2 valves are quite fine, and cost less.

If RE was making an inline 4 cylinder engine with a 2" stroke, and a 12000rpm redline, then yes, those technologies would be well suited for that application.
For a single cylinder 3.54" stroke thumper, there is simply no need for that stuff.
Even if RE put those things on the engine, it wouldn't help it to go any faster, and it might even be worse. It would certainly be more expensive.

So, unless RE decides to make multi-cylinder crotch rockets, that technology is best left to those companies that do make such motorcycles.


Take a look at this torque curve comparison of 600cc crotch-rockets that I picked off the internet.
Notice that the UCE makes more torque than all these bikes except for the 675cc Triumph, until they get over about 4500rpm. And they have 100cc's more displacement than we do. And all the hot "bells and whistles" and "go faster" technology.
But for the rpms we ride, we get more torque up until we nearly hit redline, where they begin to to a bit better. But, by then, we're out of revs anyway. So the purpose of our engine and rev range is better served and better on the road, for the rpm range that our engine is designed to rev, than these crotch rockets that have to rev to the moon to make power. Sure, they make alot of power, but they don't do it down low like we do.
The bottom line is that the UCE is stronger than all these bikes, except the Triumph, up to about 4500rpm.
« Last Edit: January 13, 2010, 04:58:50 PM by ace.cafe »
Home of the ACE Fireball 535 Bullet,  Ace GP Hi-Lift Roller Rocker Head . Pistons, cams, etc. Highest performance Bullet engine mods available .  AVL mods. Redditch 700/750 Twin mods. UCE kit soon.

Please visit my new website:
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chinoy

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Re: Why retain a primary chain drive on a UCE.
« Reply #14 on: January 14, 2010, 06:40:40 AM »

A big, BIG consideration with the new UCE engine was with traditional look and feel.  In Royal Enfield's home market, India, a huge amount of attention is paid to look and sound, and  if the new engine didn't have a primary cover, or they put the starter in a different spot instead of making it look like a distributor, then I guarantee you it wouldn't sell nearly as well when they bring it out.

Some of the stuff you say makes sense so I wont argue it.
But the above statement does not.

For Example the other day I had an old bullet guy over and he was checking out my bike. He was going oh no oh no this engine has something drasticlly wrong with it.
You must show it to a RE tech guy.
Since Im on pretty good terms with the Tech head honcho for the region.
I called him up and next morning I had the bike in front of him.

After talking to me for a few minutes about any loss in power etc.
I fired it up he listened to it for a long time and said Nah nothing wrong with it.

Then we got to discussing how this engine is totally diffirent from any other Bullet.
About how its not going to ever sound like an old bullet and why some of the older bullet guys are freaking out on the sound not being the same and other BS issues.

I think you have a few misconceptions about the Indian Market.
The number of guys who give a hoot about the sound and clasic bs is not as much as you think. 90% of the guys who are buying these bikes myself included.
Are doing so for one very very simple reason.

Its 500cc. It makes 28 BHP (Claimed).
That puts it at close to double the power output and CC size of any engine made in the country.

In the old days when India was not doing so well. We had one yard stick to measure the goodness of a bike and that was what is the mileage. Now as more and more Indians have more and more disposable income. Mileage is no longer the sole criteria to buy a bike. Now its about Power output. And top speed.

Its easy for you to say buy a Jap bike. But what Jap Bike ?
Do you know that imports are baned in the country. You can only bring in a Jap bike on a TR (Transfer of residence). Or pay a heafty fine and customs duty.
It was only a few months ago that the show rooms for Yamaha / Suzuki and Kawasaki started to import Jap bikes. They do this by paying the absurd duty rates the Indian Govt imposes on all imports. So what you would pay 10,000$ for we have to pay 20,000$
So buy a Jap bike is not really an option unless your really really loaded.
Asuming you do buy a R1 or some jap bike. WHere are the roads in India to ride them on ?

Try and look at the biger picture and what you realize is that the Bullet 500.
Is your only option.  Its got nothing to do with sound or mileage.

RE have the bigest badest Indian Bike.
The closest competition is the Bajaj Pulsar 220 which claims to be the fastest bike in the Country. (With some guy who weigs as much as one of my legs I guess).

Because with me on it. Im lucky to get it moving.

THe other day I was on the Banglore ring road. And we where having a trafic light to trafic light race. And the bullet even with me on it was outpulling all the other bikes. That is your RTR / Pulsars / Ferios you name it. The bullet 500 is the meanest badest bike an Indian can buy. Very few of the new customers really give a hoot about its sound or tech.

My only gripe with the bike so far is if the road is long enoughf or if the distance between signals is long enoughf the little bikes will pull ahead.
And when it comes to last minute braking they win here too.
The braking bit can be fixed quite easilly with some real brakes and a rear disc.
The top speed part will take some head scratching.
But first we have to get the bike to run in a straight line without wobling un-controlablly all over the road at any speed over 100.

I know it can be done. Because we have invited quite a few bullet guys to our track days. And we have had quite a few bullets which touched 135-140 Kmph down the straights and they where rock solid.
Its some silly little issue like the tyre not being seated right. A stuck swing arm bush but Im confident we can solve it.

Reading all the Pros of the chain drive is kinda re-asuring but I know the kind of power loss we are paying for that chain.

There are two camps in India when it comes to the Bullets.
THe Purists. To whom the UCE will never be considered a real bullet.
They will stick to their old 350s and Cast Iron 500s.
And then you have the new customers like me who are buying the bike for the reasons stated above.
RE in no way is depedning on the pureists to sell they new modells.
The new modells are targeted to a new audience. And a new market which has to date not been taped into.
This is the only way they will be able to sell the numbers they plan on producing.
The puresits are a teeny meeny minority.
Who anyway are not going to part with their cast irons.
Untill they get tired off being passed on every road and every ride.
By the new UCE bikes.

The old bullets where never a sucess, they never sold in numbers.
In fact the plant allmost closed down due to lack of sales.

But then some new management came in and who ever the guy is.
I respect him a lot for his guts. He is playing a big gamble. But as long the Bullet is able to attract new customers like me I think he has a winer on his hands.

There isnt a guy in my club who hasnt allready booked a 500 or is planing on booking one.
The only problem right now is there is a 2-3 month waiting period to get the bike.
That should give you some idea about the kind of intrest and demand its generating.
THe old bullet never ever had this level of interest  or demand.