S & S Cycles 750 and 865 Big Bore kits for the 650 twins.

TN_twowheeladdict

Well travelled
Location
Tennessee
Nice, but never understood this since every bike is designed as a unit. If you upgrade the power and plan on actually using the increased power for more than bragging rights you have to also upgrade the suspension, brakes, and possibly tires, chains and sprockets.
 

MrDralas

Well travelled
Location
Planet Earth
Nice, but never understood this since every bike is designed as a unit. If you upgrade the power and plan on actually using the increased power for more than bragging rights you have to also upgrade the suspension, brakes, and possibly tires, chains and sprockets.
Very true yes, but a lot of more powerful bikes use smaller chains and for the tires, well mostly your right hand controls their grip, the brakes again maybe but if your not breaking and speed limits the brakes should be fine. My worry would be crank bits and transmission bits, transmissions will handle a little power increase if you easy on them but a lot of people aren’t.

Then again, if your buying the bike and swapping a lot of parts to make it have more power right off the bat, why not just buy a more powerful bike to start.
 

MrDralas

Well travelled
Location
Planet Earth
Some people have to have the fastest Smart Car on the block. :)

I don’t think they started with a brand new smart car though. If you have a old bike and do stuff sure, but something brand new...why buy new if you wanna take away your warranty and change everything that you paid for in stock configuration.
 

Eatmore Mudd

Moderator
Staff member
Nice, but never understood this since every bike is designed as a unit. If you upgrade the power and plan on actually using the increased power for more than bragging rights you have to also upgrade the suspension, brakes, and possibly tires, chains and sprockets.
A 650 with four valve heads ? I'll bet a six pack it was originally engineered as a 750 like all the early intel reported and then later de tuned to 650 for license and insurance brackets to make it more accessible to more people. Nobody ever needed four valve heads to reach the 47 hp max limit of the A2 license.
Ducati is making 73 hp with a two valve air cooled twin and meeting Euro 4 emissions doing it. Think about it.
 

TN_twowheeladdict

Well travelled
Location
Tennessee
A 650 with four valve heads ? I'll bet a six pack it was originally engineered as a 750 like all the early intel reported and then later de tuned to 650 for license and insurance brackets to make it more accessible to more people. Nobody ever needed four valve heads to reach the 47 hp max limit of the A2 license.
Ducati is making 73 hp with a two valve air cooled twin and meeting Euro 4 emissions doing it. Think about it.
I would like to see the dyno chart on that bike. At what RPM does it make 73 hp and what displacement is it?
 

Ace

Finally made it
Location
E TN, USA
Some of you might know that I am an engine performance specialist on RE bikes. I have built the performance parts and done all the porting and cylinder head work for many of the fastest Enfields on road or track. This is just to establish a basis for validation of my opinion on this.

The 650 twins power goals can easily be met with a 2 valve head arrangement. It could also have been met with a pushrod valve train instead of SOHC. It also didn't need a 6 speed gearbox because it has a broad torque curve. No need to dance on the shifter like a typical sportbike.

The fact is that these were all marketing decisions because Enfield had been derided for many years as being behind the tech curve regarding engine design, and they desperately wanted to shed that image in the minds of reviewers and customers. People who read magazines and are not engine designers are often influenced by other bike designs that are fast, and conclude that 4-valve OHC 6-speed slipper clutch systems must be needed because superbikes have those.

Now, I am not saying that there is anything inherently wrong with these design features. Certainly they are applicable in very fast high-revving superbikes. They can even be good for grocery-getters, but they are not necessary for such riding.

The advantages of 4-valve OHC designs is short and light valve train for high revving, which means higher than 7250 rpm. There is also a breathing advantage from larger valve area, which primarily evidences itself at the lower valve lifts, and needs a bit less valve lift for getting the necessary flow rates, compared to a 2-valve pushrod layout. These are good things, and I don't discount them, but when deciding on what is needed for an application and complexity/cost involved, it is very questionable for a 48hp (at the engine)650 twin with a 7250 red line.

For example, we have an advanced design 2-valve billet cylinder head for the 535 Continental GT which gives ~45 hp at the engine in full street tune at 6500 rpm. It could go higher, but the max limit of the Power Commander can only be extended to 6500 with Dynojet permission, so that's where we stop for normal street applications. It has only a slightly larger intake valve that stock(1.8"), but the entire internal head design is different and more modernized for flow and combustion efficiency, while appearing very similar externally, and staying compatible with the rest of the stock engine stuff, for the most part.
It is very expensive, but mostly because we have to make one at a time, and have zero economy of production scale. If we were making 500,000 a year like RE, it could be very low cost.

So, to sum up, there are reasons beyond performance for having certain features that could be matched by well-engineered systems that seem to be less exotic. Marketing buzzwords can make sales, even if they might not always result in more power.
 

Eatmore Mudd

Moderator
Staff member
It's pretty obvious the slipper clutch, four valve head, extra thick cylinder sleeves , OHC and directed oil spray cooling aren't needed for 47 bhp. Also obvious It aint a superbike so copy catting superbikes didn't happen either. What's left ? They originally designed a bigger engine and small bored and de tuned it for "accessibility" and A2 license and insurance and so hot rodders would have something to do with it. Didn't hurt that they gave full access and support and cooperation to S & when they them built the Lock Stock race bike. That Lal guy is fairly sharp. Him head hunting the engineers from Triumph was a shrewd move. Those guys know a thing or two about bikes.
 

Ace

Finally made it
Location
E TN, USA
It's pretty obvious the slipper clutch, four valve head, extra thick cylinder sleeves , OHC and directed oil spray cooling aren't needed for 47 bhp. Also obvious It aint a superbike so copy catting superbikes didn't happen either. What's left ? They originally designed a bigger engine and small bored and de tuned it for "accessibility" and A2 license and insurance and so hot rodders would have something to do with it. Didn't hurt that they gave full access and support and cooperation to S & when they them built the Lock Stock race bike. That Lal guy is fairly sharp. Him head hunting the engineers from Triumph was a shrewd move. Those guys know a thing or two about bikes.
Yes, that may have been what they had in mind all along.
 

Ace

Finally made it
Location
E TN, USA
Yes, that may have been what they had in mind all along.
BTW, I don't know how many are aware, but RE India has always outsourced virtually all of their designs, and most definitely all their engines.
They were handed the original Iron Barrel design and tooling from RE England in 1955. The 5-speed gearbox was by Dr. Stuart McGuigan in the UK. The replacement AVL engine was, of course, done by AVL. So were the UCE/EFI 350/500. Not sure who did the Himalayan, but it may have been these new guys from Triumph maybe, and now the 650 twins in the British facility which they own, but it is all still hired talent from outside.
RE India has always been basically a production facility, and there was virtually no real engineering there. They fabricated and assembled other people's designs. They are a factory.

The connection to S&S was undoubtedly due to RE's hiring of all those Harley castaways for RENA. I don't really like nitrous applications for power because they are unrealistic for normal use, so the Lock Stock bike wasn't a fave of mine.
 

Eatmore Mudd

Moderator
Staff member
Pierre Terblance and Harris Performance worked on the Himalayan project.

Some of the talent they head hunted. Paul Ventura: Ducatti. Simon Warburton: Triumph. James Young: Triumph. Mark Wells: Xenphyia. Ian Wride: Xenphyia.
And they bought Harris Performance.

I highly doubt RENA had anything to do with Enfields decision to choose S & S on the Lock Stock. RENA's a subsidiary. Subsidiaries take their orders from corporate. Lock Stock was driven by corporate. Harris Performance did up the chassis. The tech center guys are sharp and could have done the deed but you want to make headlines in USA you hire the people best known in the USA for putting long stroke twin cylinder engines on the podium and in the record books not sport bike tuners. S & S was the logical choice.
 

Ace

Finally made it
Location
E TN, USA
Ahh!. ... I like Terblanche and Harris. I was sad when Terblanche exited.
I just surmised that RENA had something to do with S&S because they are so close to Harley and RENA has Harley execs.
 
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