Big news coming from RE this weekend

[ace.cafe]

I always recommend doing the external stuff like the carb and exhaust first, before doing any internal mods.
But the added displacement does bring the torque curve in a bit stronger at the lower rpms. It's one of the few things you can do to get more power at the lower rpms. Compression increase would be the other main thing.

[boggy]

How do you increase compression?

[GlennF]

How do you increase compression?

Carefully ... or things will break. You may also need high octane fuel additives.

Assuming your not bolting on a supercharger, compression increase is normally achieved by either modified pistons or shaving stock heads or fitting a modified head. Or some combination of the above. However you need to be careful or the valves may hit the crown of the pistons.

Not really a safe project to do at home yourself as an experiment. If you want to go that path I would PM Ace about what he can supply you as a kit.

[boggy]

Ah. Interesting. Wasn't sure if it was that type of thing or a method preventing a loss of compression do to bad seals or what not.

Thanks.

[jartist]

The AVL piston was discussed before as a bolt on way to get higher compression as it has a flat crown and the efi has a dished crown piston. To my knowledge nobody has tried it except for scooterbob.

[boggy]

What is is that makes say, a Suzuki DRZ400 single push out 40 hp while the Bullet does <20.  What are the mechanical elements that lead to that big of a difference?

[ace.cafe]

What is is that makes say, a Suzuki DRZ400 single push out 40 hp while the Bullet does <20.  What are the mechanical elements that lead to that big of a difference?

This is one of those questions that sounds simple enough on the surface, but has a huge complex answer.

Basically, the simple answer is that Royal Enfield doesn't even make a half-hearted effort to make horsepower. For whatever reasons, they simply don't want to make any hp with their bikes. The Japanese bikes, on the other hand, use power numbers to sell their bikes, and so they put great effort into making hp.

To start with, there is a basic equation for horsepower, which is:
hp = torque x rpm/5252
This is a true function for any engine. You take the torque reading at some rpm, and that gives you the hp output at that certain rpm.

So, we can see that rpm plays a big role, and the higher you can rev, the more hp you can make, for a given engine size.
The Japanese bikes all have short strokes, and can rev high and make high hp, because their short strokes give lower piston speeds that allow the mechanical parts to not reach their breaking limits until the rpms get very high.
On the other hand, the RE bikes have very long strokes, which give high piston speeds at lower rpms, and cannot rev as high before their mechanical parts reach breaking limits.

So, why do they have these different kinds of engines, and for what?
Well, the Japanese engines make plenty of hp, but they have to rev up to high rpms to do it. Consequently, they have poor hp output at lower rpms, because engine designs can only stretch out a powerband just so far. If you make a lot of power at high rpms, you aren't going to make much power at lower rpms. It's that simple.

So, the Japanese bikes are going to make a lot of power while they are buzzing around at the top of their rpm range, like buzzing little bees.
But, that is not really a cruiser style behavior for relaxed riding. The RE gives a long stroke with low rpm limits, and this allows it to begin the meaty part of its power band much lower in the rpms, so that you can start off from a light with some decent power and ride at moderately lower rpms with good torque and hp without revving the bike up high. It's a more relaxed riding powerband that is typical of cruiser bikes or standards.
However, since it doesn't rev up high, the numerical equation doesn't turn out with a very high number for hp, since the rpms aren't adding a lot of multiplication factor with a low revving engine. We make just as much torque, but we make it at a lower rpm, so our hp number looks lower, and it is. But we can still pull well early in the rev range with our torque production, which is something that the Japanese bikes really don't do very well.

So, in the end, it's all about what you want out of the bike, and how you like it to behave for your purposes.
The  Bullet can produce 40hp, and do it within the rev limits of our long stroke engine, but we have to modify it to do that, with mods similar to the Fireball. RE simply isn't interested in making power. It can be done, but they clearly don't want to do it.

[barenekd]

It's why Japanese thumpers don't have the character and soul of the English thumpers. They just don't feel the same, although some of them vibrate more than a Bullet!
The Hinckley Triumphs twins don't feel or sound like the old Meriden models. They have lost the character of the old bikes even though they try all kinds of tricks to get teh sound back, nothing has worked.
None of these modern machines will ever sound or feel like the old British singles and Twins
Bare

[AgentX]

If Enfields made more power, their standards of manufacture would have to go up.  That would be a pain in the butt, and prices would go up...which would kill them in the Indian market.

[boggy]

Makes sense Ace.  Good luck trying to get more power out of the UCE.

The cost of development/construction is also understandable.  Although if that Cafe is going to be 7k+ I'd be happy if it sat somewhere closer to 30hp, but I suppose that's just wishful thinking.  Maybe if they ever go twin, but then I imagine the price would be 8 or 9k.  That kinda scratch can get you a lot of motorcycle.

I know the modern Triumphs are not your classic British iron but I do have to admit, that Scrambler with the 2 into 1 Arrow exhaust sounds really good.

[barenekd]

Yup, sounds good, but definitely doesn't come close to sounding like a Meridan Triumph.
I had one with "louder than" Arrow mufflers. It sounded great, but too loud to go anywhere above about 2500 rpm! If I got outta town, it sounded great. but just as loud as a lot of Hardly Ablesons.
I traded it on on the RE. Much happier man!
Bare

[ace.cafe]

Makes sense Ace.  Good luck trying to get more power out of the UCE.

The cost of development/construction is also understandable.  Although if that Cafe is going to be 7k+ I'd be happy if it sat somewhere closer to 30hp, but I suppose that's just wishful thinking.  Maybe if they ever go twin, but then I imagine the price would be 8 or 9k.  That kinda scratch can get you a lot of motorcycle.

I know the modern Triumphs are not your classic British iron but I do have to admit, that Scrambler with the 2 into 1 Arrow exhaust sounds really good.

We don't know what the Cafe Racer is going to be, yet. It looks nice.
They have said it will be 535cc, which is good for a couple hp. There has been this vague reference to "warm cams"(whatever that means), but nothing concrete, and that would mean other internal mods to suit the cams.
We will see what it is when it comes out. That's all we can do.

Regarding our UCE kit, we'll see what that can do. too.
It will all come out in the wash.