Motorcycle specifications get interesting when comparing the construction of the highest performing sport motorcycles. Subtle differences in rake, trail, and wheelbase combined with an array of race results, illustrate the holy grail of power and handling has yet to be found. Motorcyclist magazine recently ran two monthly issues back-to-back comparing 8 of the top liter bikes in the world. On paper, the differences are very slim.
Consider these numbers:
| BTR | R1 |
| Wheelbase: 55.25 inches | Wheelbase: 55.7 inches |
| Rake: 24.5 degrees | Rake: 24 degrees |
| Torque: 100 – 125+ lbs.-ft | Torque: 75.1 lbs.-ft |
Specs and bench racing only go so far and aren’t nearly as fun as seat time, however, the significant difference in torque listed above is worth discussing. The torque in bold letters is from Harley-Davidson’s Twin Cam motor, not one of the 8 liter bikes in Motorcyclist’s test, but why are we including them in a discussion of sport motorcycles that have a 55-56 inch wheelbase and how does HD fit into either of those topics?
The specs on the left are from a bike built by Curt Winter of BTR Moto. Curt accomplished this sport bike geometry by creating his own transmission for the Twin Cam motor. You read that correctly, this is not a Sportster or Buell motor, someone used their imagination and skill to build a drive train and chassis that will put the big block Harley torque to good use on a tight road or track.
A stock, big block HD motor, backed up by a warranty, now produces over 100+ ft lbs. of torque. Common hot-rodding techniques and larger twin cam engines from S&S or Jim’s can take the HD engines well into the triple-digit torque range, hence the numbers listed above. The torque, hot-rod options, tuned sound and serviceability of these motors are no longer confined to feet forward, heavy cruisers. Notice the tiny differences in the geometry specs? Those on the right are from a 2012 Yamaha R1. Curt shoe-horned the big block motor into his very own sport bike chassis with measurements you would expect for an inline four.
He built the frame, swing arm, gas tank, and machined (by hand) various structural pieces. The tank features a cool-looking yet even better functioning vertical velocity stack for the Weber carburetor. He modified and painted an after market fairing and tail section for this track day version. This engine and transmission package will make cool Sport Touring and Cafe Racers as well.
The torque debate may continue forever but it can be argued that lots of low-end torque in a strong and sporty chassis like this results in great seat time and performance you would never expect from a big twin Harley.
Great Job Curt.
Link: BTR Moto
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Thanks, Doug, for this news of Curt’s new bike! It will be interesting to see how it performs with a sporty chassis that can make the most of all of that torque. Be sure to check out Doug’s really cool Made in the USA products at Race Track Style.
Marcos Armero says
Big Twin Torque in a Sport Bike Package?
Absolutely YES!!! I have an a Yamaha MT-01 that it´s basically this concept of bike (Not sold in USA) it´s a great bike.
mikesundrop says
As a guy currently in the middle of piecing together a grenaded Buell XB transmission, the thought of a completely different unit designed for sport bike use behind a big V Twin sounds like a pretty sweet idea. In my current aggravated opinion, a transmission upgrade would have been preferable in Buells to the power increases everyone moans about.
Mr.maniac rat says
I think that this is an awesome concept and that the BTR folks did an awesome job.
HOWEVER, when talking sportbikes we need 2 more key peices of info. Weight and hp. Otherwise it will never be competitve. I would buy one for the street though and 8 like the cafe racer/ touring ideas mentioned though.
I do also wonder about heat with that unique engine placement….
JP says
weight isn’t going to be too far out of line. small fuel tank and no water for cooling offset the chunky H-D engine somewhat.
The HP is going to be pretty good but the revs are not going to be in R1 territory nor with 125 ft/lbs does it need to be. It likely wont need traction control either. R1s kill much of that 75 ft/lbs when TC is used even with it’s cross plane crank, the H-D if tuned Twingle will act like it is built in.
micky c says
Check out RB Racing ORCA motors,139 ci,180 hp,40-55 mpg with custom fuel injection(no heat issues)and enought torque to rip your arms off,then add a 350 or 500 HP turbo kit,buy buy japper
mikesundrop says
Thanks for the link. Man, those ORCA guys are confident.
Tom Lyons says
I think he did a very nice job with that bike.
Rich says
Fantastic! I am not an H-D owner but think this is just incredible.
Doug says
Mr. Maniac rat,
I used the specs of the R1 to compare geometry only in order to emphasize what Curt accomplished with his own transmission mated to the torquey HD motor. HP was intentionally left off to emphasize torque. What good does HP do on tight roads that are the most enjoyable for motorcyclists?
Compared to his black bike (search Kneeslider archives), he was able to shorten the wheelbase by 4 inches while at the same time lengthening the swing arm by using his own transmission and case. The swing arm pivot point is also improved.
No one in their right mind is saying this bike is going to go wheel-to-wheel with an R1 on a track. However, we are saying torque is king on a tight road and even a tight track. 120 ft lbs. will go very far.
As far as racing goes:
-Sponsorship from S&S or Jims with one of their motors and this setup would make a good Battle of The Twins racer. See the Irving Vincent and Moto Guzzi MGS-01 as previous winners of that cool series.
-An entire series of Curt’s bike, like the XR1200 class, would be killer.
As far as weight goes:
Take a look at the Motorcyclist’s issues. Only the Panigale is off the chart. The in-line 4’s have a 458 lbs+ wet weight, so they can’t be much lighter than Curt’s bike. There is a minimal subframe on his bike. He’ll have to chime in on the weight because he didn’t have time to weigh it before trucking it to the AMD Show in Sturgis going on this week.
Mr.maniac rat says
You make a great point It would definately be super fun in twisties and it is inspiring that he was able to get the geometery so spot on! My only concern is top end. I think think curt should hang out with the desmo-harley guy!
Doug says
Ah, good memory! I think he tried to get in touch with him but not sure. Yea, that would be a cool project.
Doug says
Btw…we’re also not suggesting the R1 or any of the liter bikes are down on torque on their own. I’ve ridden a pre-cross plane R1 in tight roads and there’s plenty of grunt, its just different.
I’m anxious to feel 100+ ft lbs of torque in a package this small.
rohorn says
Great build, Curt – excellent contribution, Doug! It looks like an insanely fun trackday weapon. Probably sounds insane as well.
That transmission & primary take care of the worst problem of using a Big Twin in a serious cornering tool. If it is a counterbalanced engine, that takes care of the other problem.
People have built sub-400 lb Big Twin (and Sportster) powered sportbikes.
For what it is worth, the complete engine assembly in my ’88 FXRS-sp weighed 215 lbs, minus carb and exhaust, breakdown as follows:
Engine 125 lbs
Transmission 35 lbs
Primary 40 lbs
Electrics 15 lbs
Take any Big Twin, install a better/lighter primary and transmission, and you’ll end up with an engine that’s a lot lighter than people would ever guess.
I don’t have any weight numbers for Dyna or TC components – sorry.
tim says
Cycle World did a similar test (last?) month: very recently anyway: I havent read it because I am not that interested in the whole race replica thing, and wouldn’t own one.
I am interested in this bike though and I bet it sounds amazing.. Couple of questions: how does it turn? That motor is very tall and one of the criticisms of the MT 01 I read was that due to the height of the motor it would not tip in. I havent ridden one and it might be due to other factors, just curious.
The other is swingarm length. On my Street Triple the swingarm is about half the wheelbase. Apparently this is a GOOD THING for handling. Just the packaging on this mandates a short swingarm (like a Buell): were there major constraints due to that factor?
I guess what I’m saying is you better put one in a crate so I can take it for a spin and see how I go…. 🙂
tim says
is rear cylinder cooling an issue?
Miles says
Love it.
Rob says
Very tidy indeed. Love those velocity stacks, but you would have to beware lying down on the tank at full throttle…
maarten MJ-Works says
As some of you know I’m a builder myself and I can tell you that that’s a very clean built bike! the perfection in the swing arm is very tidy!
jim harrell says
Great idea, great execution, the bee’s knees. So kool!!!!!
Light is Good says
I’m a big fan of decent torque throughout the rev range and believe 180 hp is completely unnecessary, so I like this bike. The Triumph Speed Triple mentioned has “only” 123hp but between 64 and 73 ft-lbs everywhere in the rev range from 3k up to 10k. Now that’s useable power. Short-wheelbase bikes react more to torque than long-wheelbase bikes due to leverage. Short swingarms exacerbate the problem due to leverage on the suspension. Sportsbikes have short wheelbases for fast handling and are happy to sacrifice torque for top-end horsepower. Their torque curves are steeper and have a smaller rev range where torque is more than 75% of peak torque. So you get more gear-changing (sometimes near mid-corner) and lower torque because the chassis couldn’t handle that much more anyway.
Jim Kunselman says
If you had ever been in my garage over the years, you would know that I am not one of those “If you don’t ride Harley, you ain’t sh!t” guys. But I do like to root for the ‘home team’ occasionally. Curt Winter did a great build and you gotta just shout; “Yay BTR, Go H-D!!!” Good article Doug.
Bill says
Nice but…
Looks like it would ‘milk’ an over-weight or female rider 😉
Rob says
Wakan got it right with the forward facing bug catcher.
Walt says
The overall weight of this lovely build should not be a secret. Weight is a key factor in any bike designed for speed or handling. It is sadly not a factor in cruisers. So stuff a cruiser motor in a sport bike frame and you get . . . a heavy sportbike? A featherweight cruiser? GIVE US THE WEIGHT!!
Ted says
not necessarily a heavy sport bike based on the comments. It would be nice to know.
VMX1000 says
Holy cow, this is one of the nicest HD engined bikes I’ve ever seen, awesome job, the BTR guys truly know their stuff!
Kevin says
Okay, I am getting tired of the “torque is what matters on tight courses” and “horsepower doesn’t matter when you have this much torque” etc.
WRONG. Torque, is USELESS in itself as it does not include motion. Once the torque creates spinning in the engine then it becomes horsepower. Horsepower is then what moves the vehicle.
You can post 1,000 ft-lbs of torque, but if you only have 10hp you will only move at a pace of 10hp.
Torque is important in acheiving horsepower, and what makes a great torque bike is the SHAPE of the curve. The flatter the curve the better. Example: compare the MV Agusta F4 to the Ducati Panigale torque curves.
Doug says
My take on torque and tight roads is in reference to different types of output.
1. wringing a motor out to high rpm in order for the torque to be applied
2. low rpm motor that applies the torque with barely a downshift
The hp and torque curves are both important. The Panigale may have a flat torque curve and loads of hp, but the Panigale has a dip in its hp graph low in the rev range which impacts the application of the torque. Check out the riding impression….
“The old Testastretta’s legendary low-end lunge is gone, and although the upper-rpm acceleration is truly ferocious, the soft bottom end often made the superlight Panigale feel like the slowest bike here.” Motorcyclist pp.70
Bryan says
Thank you Kevin, you beat me to it. The torque numbers themselves are fairly meaningless, since all vehicles use gearing as a “torque multiplier”. It is the torque at the wheel that matters, even more so when you have to move +1000lb of motorcycle and rider from a stop. Not as important on a lighter sport bike.
A while ago, the marketing department at the big iron motorcycle decided that they couldn’t compete on power, but noticed bigger torque numbers on the spec sheet so decided to sell the idea to the unwashed masses that torque is king.
If you want to evenly compare a bikes ability to move forward, it still comes down to power, not torque.
I have ridden the Yamaha MT01 and I thought it was silly, a cruiser that was unsuccessfully trying to be a sportbike. Of course awesome Vtwin sportbikes are possible, ride any Ducati.
Harry says
The MT-01 doesn’t have an R1 geometry and probably weighs 50 lbs more than the above bike.
Ducati has to sort out that dip in the hp curve to get the low end torque back
Kevin says
This bike is absolutely beautiful. This is so well done. One of the best H-D powered bikes ever. Right up with Mule. This would probably be fun and unique to ride.
I would have to see the power and weigh though.
tim rowledge says
Torque at the motor is uninteresting. Torque at the back wheel is what you value. A million-rpm motor with puny torque would be mind-blowing through a 10,000:1 gearbox. A million times puny is quite likely to equal “holy-cow!!!”
todd says
This is nothing short of awesome Curt, I hope you were able to take it out to the American Sport Bike Night last night (that I missed again).
Here’s a good way to look at torque:
What is heavier, a pound of iron or a pound of aluminum? Horsepower is a measurement of power. There is no way, ever, that a bike with less power will ever be more powerful than a bike with more power – regardless how much torque the motor generates. Torque is effort, that’s all. Some bikes require more effort to do the same thing (HP) as other bikes.
Torque is a meaningless number unless it is backed up with RPM. If this 125 ft-lb motor only spins at 60 RPM then it will be no faster than a bicycle which also has 125 ft-lb at 60 RPM. Greater RPM allows lower gearing which provides greater torque multiplication at the rear wheel. This can then be calculated as thrust. Horsepower is the end result, it tells you how much power your torque is generating. More torque does not mean more power. In fact, an increase in torque with a reduction of RPM is actually a loss of power. For any given speed you will be required to have a higher gear ratio which will translate into less thrust.
Don’t let my arguments overshadow the fact that this is an awesome build by Curt Winters. This shows his tremendous skills – and if he had some help – the skills of his team.
I imagine this bike is no slouch. If it’s making a peak 125 ft-lbs, that would likely be at around 4500 RPM and with a 6000 RPM ceiling this thing is likely making close to 130 HP. If that is true then performance will be close in line with a GSXR 750. Pretty awesome indeed.
Doug says
“There is no way, ever, that a bike with less power will ever be more powerful than a bike with more power ”
no one ever stated that, todd.
todd says
People do. The common misconception is that a bike with more torque at the crank somehow has more power even if it has less horsepower (?!?). If a bike has more power it will accelerate harder than one with less. If a bike has less power it has less power. A 50 HP bike with 100 ft-lb of torque will never out accelerate a bike with 100 HP and 50 ft-lb of torque. Simply put, the 100 HP bike is twice as powerful as the 50 HP bike so it will accelerate at twice the rate.
If you reduce the RPM you either reduce the speed or you raise the gearing to maintain speed and reduce the driving force (thrust or torque at the rear wheel).
There is typically no need to use full revs on a sport bike. A bike with 130 peak HP will easily put out 65 HP at half throttle, or about as much the big twin (96″) guys have at full throttle.
I understand the lack of need for power. I like a nice smooth engine in a light chassis that handles well. I’m perfectly happy with a bike that has less power than a Harley, I just don’t choose to ride a Harley because of the weight and slow handling and vibration. To each his own and I’m glad we’re all happy here.
-todd
Doug says
todd,
The point of the article was Curt’s build*
The point of Curt’s build is to make use of that motor’s torque by putting it in a sporting geometry & wheelbase.
Previously, the stock primary & transmission pushed the wheelbase out to 59+ inches. The primary also created other challenges with motor placement which then created challenges with the swingarm pivot point.
I mentioned all of the liter bikes in the Motorcyclist issue because they all have similar measurements in rake, trail, & wheelbase. i.e. over decades of building sport motorcycles with a telescopic front suspension, those sets of chassis specs are the current benchmark for handling.
For many riders, there is value in riding twisty roads with equal or greater amount of torque as the repli-racers, but using a 1/3 or 1/2 of the revs to apply that torque. The HD motor also happens to appeal to riders who want simplicity of air-cooling, hot-rodding capabilities, and a sound (when tuned) that is great, especially when a bike like this motors by.
* The entire build was done by himself
Tin Man says
I will take 60 Lbs of torque at 3K over 60 Lbs at 7,500K every day. Not everyone wants to ride a Bumble Bee !!!
todd says
Good analogy. The bike you chose will never accelerate as hard as the other bike because of the gearing compromises a low RPM motor needs to make. Bikes with 60 ft-lb @ 7500 typically make around 50 ft-lb at 3k RPM (e.g. F800) so that, with the benefit of lower overall gearing still gives you more torque at the rear wheel.
High powered bikes are not as peaky as the perception goes. The misconception likely originated from Kawasaki two-stroke 500’s. Modern inline engines have huge, flat torque curves that put V-twins to shame. For instance, the Kawasaki GTR makes at least 70 ft-lbs from 2500 RPM all the way to 10,000.
Again, this in no way detracts from the awesomeness of Curt’s bike. I highly respect his abilities as a craftsman and the abilities of anyone that can begin to exploit the potential of such a machine.
-todd
rohorn says
And my old H-P RPN calculator (Long gone, sadly) makes more satisfying horsepower calculations than my algebraic TI.
The calculator riders need to read Kevin Cameron’s latest TDC column, among other things – and how power delivery is more important that peak HP. A Big Twin, with equal HP to a given four, will deliver the power to the ground in a lot easier to control manner due to the different rate of power pulses per foot traveled. The twin is also more likely to have a higher inertia crank – that helps as well. If you wonder why you’d want that, go ask Honda’s GP team and look at how much weight they added to their cranks a number of years ago.
As was pointed out above, there’s a lot more HORSEPOWER waiting to come out of this engine. Heck, if you really want to do it right, learn a lot from others then design/cast/machine your own heads from scratch. People have done harder work than that – for fun – around here. And if that’s not enough, make it bigger. And if that’s not enough, supercharge it – its the American Way!
todd says
no arguments here. When horsepower numbers are equal a twin will allow more traction, hence the whole “Big Bang” trend for multis.
The comparison is difficult to make, there aren’t many 65 horse inline fours around any more.
In certain industries, like automotive, physics is used to help understand the dynamics of vehicles and explain the why’s what’s and how’s of what you’re feeling. I understand the tendency for people without scientific backgrounds to be skeptical of natural laws but it’s the only quantifiable way to judge performance. Yes, I do look at my bank statements to see how much money I have, I don’t just spend it until it stops.
-todd
Deanna says
Quantifiable?
See tom’s equation below and apply it to curvy roads
Tom Lyons says
Torque x rpm/5252 = hp
You don’t get one without the other two.
You can just as easily get more hp by raising torque, as you can by raising rpm. The equation clearly shows it.
In fact, as the equation also shows, for any given rpm, the engine with the higher torque at that rpm will also have more hp at that rpm.
leston says
I knew this would turn into an internet argument of torque vs hp.
get over it folks.
This is a fantastic build, and I bet its fun as hell to ride!
congrats on the hard work
frederick says
nicely done but why all the fuss.
probably the most underrated and unloved motorcycle on the planet offered out of the box is a 101hp, 90ftlbs torque lumpy cammed fuel injected Harley twin in a lightweight 440lb sport bike chassis with trick brakes and an upside down fork … and you can pick one up cheap.
got one…and its not for sale
B50 Jim says
James Watt devised the torque/horsepower equation as a method to rate his steam engines in a way his contemporaries could easily understand, as a means to sell them. He measured the average amount of work an average horse could perform during a given time, then applied the same amount of work to a steam engine. A simple calculation of steam pressure, piston area and stroke yielded torque in pounds/feet; then he measured the amount of work the engine did at a given rpm. Comparing that figure to the horse-derived numbers yielded the familiar equation, and we’ve been using it ever since. Actually, the mental image of 100 horses hooked to the front of a motorcycle is ludicrous, but it’s the rating we’re accustomed to. Let’s just say that torque, rpm and horsepower go hand-in-hand; you need all three to make it go fast. However, an engine that makes its power at lower rpm generates far less internal friction than an engine spinning a zillion rpm, so it can put more of its power to the ground rather than using it to overcome the sizable drag caused by friction. It’s all tradeoffs.
That being said, Curt’s bike is a work of art — more a motorcycle wrapped around a great engine than an engine shoehorned into a motorcycle. And yes, with all that torque it will rocket off the corners; with the ability to rev, the torque is the gift that keeps on giving.
todd says
Don’t forget how the lower spinning motor needs more gearing to get up to speed (like the bicycle, remember?). Taller gearing means less torque to the ground. Power is power, there is not two different types. You either have more power or you have less (you could have the same I guess). The one with more power -horsepower according to Mr. Watt- wins.
-todd
rohorn says
That’s why the much higher revving 600 supersports make more horsepower and are so much faster than the literbikes.
todd says
Most literbikes I’ve seen have more horsepower than 600 supersports. There are the older ones like the KZ1000 or the GS1000 that would be slower than the modern 600’s since they were around 80-90 horse and weighed twice as much. I don’t know if those are the ones you’re referring to.
-todd
rohorn says
My reply was a sarcstic comment about some people’s preoccupation with RPMs. I’m glad there’s a variety of ways to get the same result.
But you are right – a modern 600 is faster in every way than my 25 year old GSXR1100 – and far faster than anything available 30 years ago.
For that matter, I was able to run away from R6s and such on the track on my ZX9R – on the back straight – everywhere else, they ate my lunch.
Yeti2bikes says
If any of you would like to see the torque vrs. horsepower question answered weekly through a 10″ wide rear tire, it happens on the 1/4 mile every Sunday. NHRA pro stock motorcycle category. Televised on ESPN2.
This season it’s V twins – 6 event wins = Inline fours – 0 event wins.
B50 Jim says
High-RPM horsepower and lower torque means more gears. More gears mean power-robbing friction. Might as well get the torque to the track directly. V-twin success in NHRA Pro Stock could be for the same reason they run so well on dirt tracks — the V-twin power characteristics allow the tire to do its job more efficiently on a microscopic level where the real action takes place. I believe Kevin Cameron spoke to this some years ago.
todd says
The current (US domestic) “World Champion” title holder is Larry “Spiderman†Mcbride and his 1500cc Kawasaki-ish 4 banger, close to a half second faster than Tommy Grimes V-twin. Of course, titles don’t last for long.
-todd
Tom Lyons says
There is a limit to the amount of torque that can be attained from a certain size engine, normally aspirated.
So, these racing classes chase the higher rpms because that’s where they can go to get the hp, and they move the torque peak way up there too, because it’s a multiplicative equation where if you peak your torque at a high rpm, it makes better hp. For them, everything happens at the top of the rpm band.
The issue is that it’s relatively weak until it gets up to the powerband rpm, but once you get there, you can gear it to stay in that short little powerband. Shift shift shift. That’s the mantra of the high rpm bikes, which is where the road racing bikes aim.
The lower rpm bikes get their torque lower in the rpm range, and they get gobs of it. They are on their power curve practically right out of the gate. They get the hole-shot, which is a real big part of drag racing, but not much of a part of road racing. The fastest accelerating piston-engine vehicles in the world are big-inch pushrod V8 engines which top out around 9k rpm, and go from 0~320mph in under 5 seconds. Top fuel dragsters.
And then for something completely different, a nice cushy wide torque curve is great for cruising, which has nothing to do with racing at all, but more people do that than all the racers put together!
Different strokes for different folks!
A good engine designer creates a set of torque and rpm characteristics which best suit the intended use of the engine. There are many ways to skin a cat.
todd says
Those top fuel engines have 1500 hp. Power matters everywhere if you want acceleration AND speed.
My experience is that low RPM motors have even narrower power bands. I rode along side a friend on his H-D and I noticed he was typically shifting into 4th gear by around 40 mph. At the time, I was on my old 650 Seca and I was just shifting into second at the same speed. We weren’t drag racing so maybe he would have held each gear longer (to use more of the bike’s HP). It did usually bother him that my bike was faster when we were trying so he didn’t try often. When we went places people typically talked to us much more about his bike than my old Yamaha…
-todd
Deanna says
That’s nice todd.
Now where we’re we? Curt’s bike, right.
B50 Jim says
When you get right down to it, very few of us have the skill to use the all power available in the average bike, much less a hot V-twin or inline 4 or anything else. What’s important is the the engine’s characteristics provide smooth, usable power over a wide rpm range. My B50 makes all of 34 hp from one cylinder, with a wide torque curve, and that’s more than enough to get me into trouble, but when I ride within my skill/comfort range it’s a fun bike, and that’s where it’s at.
mullet says
Are there any video’s of this masterpiece? I need to hear/see it running/moving/racing! I am a MASSIVE fan of this kind of build, and as much as the pictures are beautiful, i yearn to see it in action.
Kevin says
Tod – Great explanations of the torqe – RPM – horsepower debates. Torque and rpm are both ways to get power. You need motivation (torque) and motion (rpm) to move, and that is power.
One thing to make note of is the importance of the shape of the torque curve (directly relating to the shape of the power curve). The flatter the better. This is when you will find bikes the most fun. Bikes that drive out of a corner at low revs, but pull very strong. But get them up in rpm and they rocket. You get the best of low rpm power and high rpm power; minimal shifting and pure acceleration.
Now, back to Curt’s bike. While it may be down on power and thus slower, it is still a great bike for a different reason. It simply is not a cookie cutter sport bike. It is a beautiflly done custom, with unique powerplant choice. It will get a lot of attention. It makes great use to show off the beautiful steel trellis frame and air-cooled pushrod twin.
Brian says
That’s a really awesome bike! I love it. I wander if there is enough intrest in bikes like these for harley to promote they’re 120r crate engine for a series? Or if that engine would even be a good canadate for road racing?
deanna says
the XR1200 class is fun to watch, but a whole series of the above bike with 120 motors would be extremely cool.
Mike says
HD has been trying to figure out how to get the younger buyers in the dealerships…HERE is the answer!
steve w says
I just thought I would throw this in. I have 2 S&S 124cu in. powered bikes. Bone stock the engines make 126hp and 132ft lb torque @ the RW. A bit of mild modification gets you in the 140/140 range. However for this type package I would like the 111″ package better. Square design of 4 1/8 x 4 1/8. Very interesting build.
jerry g says
steve w – are the S&S motors evo-based or twin cam-based? I believe the twin cam might be ideal for this setup, but curt may be able to work magic with the evo too??
Curt says
Jerry G.
I thought about using an evo motor, I have a 127″ ultima that makes 140HP and 145 ft.lbs. But the twin cam had a superior rear mount and lent itself better to the transmission. I’m going to install the 98″ big bore on this one while retraining the stock 4″ stroke, it will be very close to square and I’m shooting for 120+ HP and torque. This will be a track bike so I won’t mind squeezing every bit out of it. I like the talk regarding an AMA class for these style bikes. Would be a cool show.
rohorn says
http://thekneeslider.com/archives/2008/06/03/rising-interest-in-big-twin-racing/
Steve says
The XR 1200 class is fun to watch and the sound is wild. I imagine a field of these types of bikes with the big twin would be more entertaining.
Hooligan says
We had a XR1200 race class last year in BSB (British Super Bikes}. Now replaced with a Ducati 800 something class. The Dukes are not as exciting, The XR races were chaos, great fun to watch.
Brian says
Hey Curt,
just wanted to see if you had any track side updates? how does it handle around the track? any riding impressions vs the TC sport? what does weigh in at? it would be awesome to see a class of these bikes run back to back w the xr1200’s at the AMA races.
Curt says
Brian.
Just went to the track yesterday and was very pleased with the way it worked. The bike was very stable yet turned excellent and changed direction quickly. It still needs fine tuning with the suspension, but even that seems to be very close. The stock motor is ok, but doubling the HP and torque will be a huge improvement. The goal for its first outing was to qualify the chassis design and geometry, its very good, suspension tuning will allow me to run deeper and push it a little harder. By the end of the day I was able to run mid pack in the B class, not bad for the first time out on a prototype bike.
Gidgster says
Hi Curt,
Love the bike… I have always been into EVERY kind of v-twin sportbike, so seeing a custom build like this is great! As a current rider of a Honda Superhawk, I understand how great the low RPM “torquey” power characteristic is. “Sneaky” fast! Sounds like a great bike to ride; what a superb build.
I am curious about the weight though… it would be fun to have an idea how light a big-twin based superbike would be!
Just a thought if torque reaction from a (relatively) short swingarm ever becomes a problem on the track: the swingarm could “pivot”on two separate bolts, hence allowing the swingarm pivot to be mounted further forward on the bike (in essence “wrapping” the engine). I thought about this while mulling over the Ducati’s excessively long engine.
I would love to see some Vid’s of the bike in action!
-Gidgster