The Kneeslider

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BTR Moto GP Big Twin Sport Bike Track Day Action

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BTR Moto GP heads to the trackCurt Winter took his latest bike, the BTR Moto GP, out for a little track day exercise at Thunder Hill Raceway. If you watch the video, you have to remind yourself, this is running a stock 88 cubic inch big twin engine. Since then, Curt’s swapped it for something a little more muscular, a 95 inch, 109 hp, 119 foot pound engine which translates to even more performance.

It’s too bad Harley doesn’t want to take a little side trip off in this direction because they have an engine that could be a lot of fun if wrapped in the right frame and bodywork, instead of being confined to long wheelbase cruisers. It also makes you wonder what the judges were thinking when Curt’s bike placed third in the performance class at the AMD Championship, but let’s not debate those points again, decisions have been made, end of story.

It’s nice to know someone isn’t afraid to think outside the conventional box and it proves those big V-Twins work great in applications beyond what we’re seeing from the factory. Looking good, Curt.

Link: BTR Moto

Video below:

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Comments

  2. I’m most partial to the sound of pushrod Triumph/BSA triples, but this bike sings a great American V-twin song. It’s also fast, and could show a lot of good bikes its exhaust. Will Harley ever build something like this and take it on the circuit? Probably not. GP-style race bikes run counter to H-D’s bad-boy image; too wine & caviar, not beer & brats. Dual rear shocks vs. single shocks. The Motor Company has been highly successful with its formula; why risk messing it up?

    Too bad.

    • Most Harleys come with dual rear shocks, some come with single shocks. I am not sure what point you are making with that comment. Please advise.

    • It does seem kind of silly getting so excited about this bike when Buell was mass producing something arguably similar up until not very long ago. Not to belittle was BTR has built, but the man’s got a point.

      • Very similar, but not using the Twin Cam motor. The hot rodding of those motors seems to have huge potential now that Curt built a compact drivetrain for it.

        I like how that bike transitioned in the tighter left-to-right section. It also pulls hard out of corners

  5. H-D wasn’t exactly over the moon about Buell, either. Sport bikes aren’t in its genetics.

    • I bet there are plenty of HD employees who would love to see this bike. It’s the old guard management that needs a shake up, not the whole company.

      Everyone of those XR1200 racers would love this….120hp & matching torque is not difficult

    • Harley has some racing in it’s genetics. You just have to go to the ’60s and back to find it. Indian versus Harley was THE battle royale in the teens and ’20s.

  7. Hey Paul, you guy’s ought to build something like this and come to the track with me. So much fun man, really get people scratching there heads.

  8. http://thekneeslider.com/archives/2007/07/16/when-the-hd-sportster-was-the-fastest-motorcycle/

    The Buell was an exploration into its roots. where they ORIGINALLY came from. THEY chose to turn their backs to “the fastest motorcycle” and never looked back, and when presented the opportunity to make it happen again, they killed the line. “Sportster” wasnt a name given lightly at the time, now its just a joke.

    Those that have ridden the HD line, and the Buells KNOW what the sportster COULD be, and should have turned out to be.

    • Someone speaking my language! Buell went awry when they didn’t do something similar to this with a worked big twin and six speed setup. In comparison, Factory specs for a 2008 Buell Firebolt Xb12 103.00 HP (75.2 kW)) @ 6800 RPM 113.90 Nm (11.6 kgf-m or 84.0 ft.lbs) @ 6000 RPM Thats out of Sportster DNA.

  9. I imagine that was the last sound they were expecting to hear when he passed those guys. Looks like quite the hoot and such an excellent build. I really need to come by the shop to see the bike in person. Cool stuff.

    -todd

  10. Quick question: what’s the benefit of running the “Twin Cam” motor over a Sportster base one? It seems like you can get similar power from both until you get into the 106″ + sizes. Did the benefits justify the awesome effort of the new transmission?

    -todd

    • Zippers make a a 120 cu sporty, S&S 100 cu,after this case size becomes an issue(also gear box,clutch and primary)big blocks are cheaper.NHRS are getting up to 136 rear wheel HP (bout 150 motor)from a sporty.more gearbox and drive line options with twincams,and cu options up to 150 odd.

      • So nothing but size? Why hasn’t anyone built aftermarket 4 valve heads for any of these engines? Seems to me the thing to do is shorten the stroke, balance the crank, and get some flow through the heads if you really want to make power. After a while these cubic inch wars will get old.

        • they have ,and over head cams but remember harleys make about the same torque as HP so it really makes modern jap motors look silly,consider a 1950s based motor with pushrods and 2 valves,compered to 4 valves over head cams ,high comp trick fuel injection,RB racing make turbo harleys with 500 HP, bout the same as a buse with a turbo but the harley has twice the torque.

        • Nothing but size?
          Nothing but more valves?
          Nothing but more cylinders?
          Nothing but more RPM?
          Nothing but more titanium?
          Nothing but more electronics?

          All of the above are used in the pursuit of more power. Only one of them doesn’t really cost much more.

        • Mike that sounds just like one of my old posts, and it is the thing to do, ,just add some electronics, and injection for the mix and let her rip.

  11. Someone at DMG: Tell me with a straight face that a national Big Twin roadrace series wouldn’t bring in a crowd (And sponsors). I don’t save many magazine articles, but Kevin Cameron’s TDC piece from a few years ago on such a series is still on file. MotoBT, PLEASE!!!!!!!!!!!!

    Curt, Thanks for sharing your work and especially the track experience!

    • + 1 !

      Imagine the sound. There’s a place for the high tech racing (obviously), but plenty of people would be interested in seeing what these bikes could do, especially since there is a direct link to what they ride.

      The crowd at Daytona would double in anticipation of the “support” race series to fire off because of that connection. That presents a significant business case difference than the XR1200 class.

      How many bikers show up for bike week riding a bike with a big twin HD engine? Hundreds OF THOUSANDS

      • But would the series be restricted to Harley? I would hope not, too many other manufacturers make serious high CC twin engines. Triumph and Kawasaki come to mind, as well as the Zuk M109s. A spec bike class is nice, but I would rather see HD compete against other manufacturers than their own kind

        Curt, fantastic build.

        • Someone (ahem!) thought this big twin racing would be a great idea a little while back, … about 6 years ago, actually. That someone STILL thinks it would be a great idea.

          • Obviously you haven’t looked at a modern Yamaha. More displacement, more compact package, stronger internal, lighter, 4 valve heads, air cooled, and belt drive. Not to mention lower cost, and with strong aftermarket support (patrick racing). I would prefer to buy American, but its hard when i already own a better bike.

            • I’m not sure how the Warrior engine is lighter when it weighs 100 lbs MORE than the one out of my FXRS. The Harley one can be made a lot lighter and more compact than the Yamaha, as seen on the BTR above, Ecosse Moto, numerous Confederate drivetrains, etc….

              Patrick Racing? Really?????
              http://www.rbracing-rsr.com/patrickracing.htm

              If Patrick Racing is strong aftermarket support, then what’s the aftermarket support from, say, S&S, NRHS, etc…?

              I’d gladly go the Yamaha route – if it could be made into a much lighter and smaller winner – but compared to what can be done with the American aircooled pushrod twin aftermarket, it looks like a big boat anchor to me.

    • I honestly think this is a great idea, especially at the national level. A class with GP-level chassis tech (or at least open rules regarding chassis, suspension, etc.) using air-cooled Big Twin cruiser engines…kinda like MotoGP CRT’s with Harley engines. It would likely spice up the fairly bland (from a technical standpoint) class lineup that AMA/DMG currently offers.

      • I think just keeping the V-twin concept. No restrictions on country, manufacturer, type of cooling, capacity etc. Have a minimum weight to keep superbikes in line and let rip. It would be sad to see a great idea stifled by patriotism or favoritism to a single brand whilst stopping development of the engines in the last century. It would be great to see a line up of Harley, Victory, S&S, Confederate, Ducati, KTM with all the Japanese brands and hopefully some Chinese/Korean bikes on grid with the handicaps matched so we can see some fun racing.

          • They don’t it’s true but we all want to see a race where a two liter v-twin takes on a one liter twin, with the smaller dominating in the twisties and the larger overtaking on the straights battling it out to the bitter end. I think go hard with the handicaps and let all comers join. Liquid cooled can have weight penalties, air cooled can be any capacity up to say 3 liter or something equally mad.

        • Unless Ducati and/or KTM (or anyone else for that matter) produced air-cooled Big Twin engine for a cruiser, or even just a air-cooled Big Twin engine, personally I’d say no to them. Liquid-cooled twins…there is already a class for them. But the idea of HD, Victory, S&S, Confederate, the Japanese brands…with their big cruiser engines, definitely. Of course, a few other rules for the engines would likely have to be established. But in this case, less is more.

          I could see something like this, if it ever took off, being the next great American-born motorcycle racing class (at least here in the U.S.)…much as Superbike racing was. One can dream anyhow…

          • The only thing keeping big air cooled twins from competing in races against Ducati’s and KTM’s is power. Harley is currently eligible as far as I understand, they have not been banned from competing in any series. So yes, I guess you would need to create a new series that outlawed liquid cooling or OHC or kept the engine capacity unlimited and then you’d have something.

            -todd

            • I agree with you…outlawing liquid cooling and such, and allowing for unlimited displacement (perhaps even having a displacement minimum) would likely be crucial to such a class. Without it, it wouldn’t take long at all for liquid-cooled machines to dominate and over-run the class, effective killing the spirit of it.

              After all, it was the coming of a liquid-cooled twin (Ducati’s 851) that was basically the beginning of the end of Pro-Twins racing in the U.S.

  12. To Rohorn.
    I actually contacted the AMA and asked what they thought of the idea regarding a class for a big twin like this. I was amazed when they said they thought it would be great, unfortunatley they already have a full program and were pleased to announce that they just signed with Harley for another 2 years in support of the XR1200 class.
    To Micky C.
    The Sporty is actually a great choice for a bike like this but as we know it’s already been done. I wanted to do something with a big twin in an effort to use this engine in an environment that was completley new. This complete power plant is 1/2″ shorter than a Sportster and achieving over 100hp was as simple as dropping in a set of cams and bumping the compression.

  13. I think Doug has the big picture. In 98 I bought a FXDX 88″ twin cam which is basically a Sportster with a big engine. I was so disappointed with the performance I didn’t know what to do with the bike. Then one day a Harley catalog showed up in the mail and I found a Harley 95″ OFF ROAD DRAG RACE KIT “ONLY.” The kit was complete with all Harley parts, heads,jugs,pistons,cams, push rods,choice of carb, and ignition. To make a long story short. I had to use compression releases to turn it over even with the most powerful after market starter. Now the bike will fry the tire or lift the front wheel if one chooses to bang gears. Way better than the Buells I have ridden. 12′,000 miles of hard ridding and city traffic with no issues and same plugs. Would be a fun race series. ..Z

  14. Shame Harley would never do anything like this themselves, mostly because of their stubborn customers. I like some of Harley’s bikes; the VRod and Road Glide, and have many friends that ride Harleys. One thing always amazes me though; I hear Harley riders complaining that the bikes aren’t carbureted anymore, and trash talking the idea of water-cooling for better performance. It baffles me that anyone could ever complain about increased performance, fuel economy, reliability and adaptability to cold and high altitudes. Carbs better than fuel injection? Give me a break!

    • This is because you’r old Harley riding buddies have re-jetted a carb but have probably never heard of a new fuel map for their EFI controller. Just sayin’… I never heard of a fuel map until I put a new pipe on my XB Buell.

  15. Most of us who remember working on carburetors hope we never see one again. Many automotive mechanics (or “techs” as they’re now called) have never seen a carburetor outside of a museum. They’re amused with tales told by the old-timers of endless fiddling, swapping jets and needles, synchronizing throttles, adjusting chokes and accelerator pumps, sorting linkages and troubleshooting floats. Even the best carb wizards tore their hair out trying to get it all working right, only to have the owner take it to Colorado and come back complaining that it wouldn’t run properly up there. Except in places like NASCAR and NHRA, which are dedicated to perfecting outdated technology, carburetors are a thing of the long past and nobody mourns their passing.

    A street car’s engine with a carburetor lasted no more than 100,000 miles before the rings and top cylinders were worn so badly the engine had to be torn down, bored and rebuilt, a result of the choke dumping raw fuel into the manifold before it was fully warmed up. On a sub-zero morning there was an even chance that the engine would “flood out” with gasoline that burned only reluctantly at such temperatures, fouling the plugs and prompting a call to service station to send a man out to try and start it. On many a cold winter morning customers called us, saying, “I think the gas line’s frozen. I pumped it and pumped it and it’s not gettin’ the gas!” Of course the engine was full of raw gas; we drained the oil, which was half gas, unbolted the carburetor and soaked the gas out of the intake manifold, removed the plugs and burned them clean with a torch, then put it all back together with fresh oil, adjusted the choke and started it. Even a well-sorted carburetor didn’t work very well until the engine was fully warmed up. No mechanic misses those days. Today’s vehicles start right up at the turn of the key in any weather, run well right off the mark, and last a quarter-million miles.

    The Amal Concentric on my B50 is about as simple as a carburetor gets, but I still find myself having to adjust it as it wears, and after about 4,000 miles it will be worn so badly I will have to bolt on a new one.

    Digital fuel injection is better in all ways, on bikes and everything else.

    • Jim, check out a 42mm Mikuni flat slide for your B50 or a VM30 from Sudco if you want a nice carb. I forgot the size of mine but it always fuels perfectly, cold or hot. Regardless, just put you old Amal in a display case.

      -todd

  16. You cant compare your B52 woes and old school automotive manufacturing precision wonders with a more modern well placed carb setup from a nineties or newer quality japanese motorcycle..

    I very much miss the modern injected machines which manufacturers and computer companies join hands and rape the guy who likes to take care of everything himself and places value in reliability combined with simplicity.

    I’m not interested in being the camper with the motorhome. Give me fuel injection for my economical four wheeled driver and an eccentric but predictable carburetor for the motorcycle please.

    • My “eccentric but predictable” Amal once spit a fingernail-sized chunk of its slide down the throat of my B50, where it bounced around inside an out-of control cylinder until I was able to shut it down, but not before it did its damage. I had to buy a new jug and piston; lucky it didn’t wreck a valve and ruin the head as well. We only used carburetors because we didn’t have anything better. Now we do.

  17. You know I’m suprised no one brought up Yamahas MT-01 yet. It was this same concept, but wasn’t sold in the U.S. I have no idea if its out of production now, but there’s the rival entry for this thing in a big twin in a sport chassis race series right there. The Irving-Vincent fro BoTT racing would another, I believe it displaces around 1300 to 1600 cc’s.

    • The MT-01 is close, but it the overall bike size is enormous compared to the BTR in both height & length. I saw it at Cannery Row. It is the size of an R1 which boggles the mind a bit. At the same time he pulled it off…doesn’t look out of place at all. Actually, the bike looks very balanced.

      Don’t forget the Guzzi MGS-01. That would be a great race…

      Irving Vincent from BoTT
      BTR Moto
      MGS-01
      MT-01
      Wraith

      • I would add Wakan (not sure if they are still in business) to this list (and the one below) as well. Their Track Racer looked very impressive, and to me (along with Curt’s bike) is the epitomy of the types of machines a big-twin racing class should and would hopefully produce.

  18. I remember that article, and I remember wondering if there would be a restriction on valve actuation. At the time I had just bought my first Ducati after my 3rd Sportster and was waking up to the wonder of overhead belt driven cams (OK I had a Honda CL175 also but it wasn’t quite the same) and it made me wonder how, with greater displacement, they would stack up against HD (and other cruisers) with pushrods. That 900SS was light years ahead of my XLH883. Maybe Duc can bring back the Indiana with a stroked version of the Dualspark 1100 engine in the Monster/Hypermotard so they can come in a play?
    I’d be down with that!

    • I know, my ’93 Monster 900 is at least twice as powerful as a similar sized Sportster motor and the Monster isn’t even considered powerful.

      -todd

      • Indeed, and so a 97 Buell S1W has about 25hp up on your monster, and that isn’t even considered powerful today.

        • more like 15 and that’s from nearly 50% more displacement. Still, 100 hp is a bunch in my book.

          -todd

  19. Well, I’d love to see a modified 1200 XB Buell and the BTR going for it on the track!
    88 cube XB with cams and headwork. I suspect there wouldn’t be alot in it.
    As much as I’d love to see Harley Davidson build a true sports bike again, its just never happen.

  20. Nice build but that engine is being overrated here on the kneeslider (imho)! I did a rebuild in a KTM 990 superduke, it took 12.5kg off the bikes weight and that ktm engine is one of the best (and best sounding) twins out there to take on a track. I think this build would have made way more sense round one of those engines than round this one. I know that that’s not the point but still, why make something with that potential around an engine that will never reflect that performance…?

  21. Every time we’ve brought up the idea of racing air cooled cruiser twins, several commenters will jump in with “Why not Ducati?” or “How about liquid cooling?” or some other such suggestion. It’s because that’s not what we’re talking about here, you might as well ask, ” Why not inline fours?”

    This is a suggestion for a new class, not something already out there, attracting the attention of those who ride air cooled cruiser twins, not Ducatis or KTMs or anything else. Saying your Ducati is superior to these twins isn’t relevant to the conversation. This isn’t hard to understand unless you’re just taking a shot at Harley or one of the other air cooled cruisers a lot of guys ride. All I can suggest is when this class is racing, go to the concession stand and buy a burger, then you won’t be bored.

    • “Attracting the attention of those who ride air cooled cruiser twins, not Ducatis or KTMs or anything else.”

      I think the Ducati comment is a relevant one when referring to their air cooled twins. Thus making it a class that isn’t just being created to give Harley a place to play, but any other bike which is also an air cooled twin in a sporty, track oriented frame. I don’t know enough about KTM’s, but air cooled Ducati’s and Harley could play nice.

      If a class is introduced which requires only one brand of motor in a completely custom frame, how many would join? Unless you are talking about riding around on stock Harleys, it is more of a dream unless there is allowed to be more than one brand of similar class of bike.

  23. The classes have traditionally been set up as displacement classes, and so this naturally bred higher-revving engines to complete in the classes that didn’t allow any higher displacements. RPMs was the only place they could go for more power.

    All you have to do is make the classes rpm-limited too.
    Such as “:1200cc and 7000 rpm max”.
    And that will take care of that.

    Or, you could have the “100hp class”, and we don’t care how you get your 100hp, but you can’t be over.

    It’s the class structures which have bred the machines that win these classes. Make different classes, and you’ll have different machines winning.
    As long as you structure the classes to favor high-revving multis, then you’ll have high-revving multis dominating the races. The answer is in the class rules.

    • Very valid points!

      I like your suggestion of a 7,000 RPM rev limit. I would also suggest a minimum weight based on engine size and/or output that could be adjusted to maintain parity and keep costs in line. This could be used to discourage racers from spending a lot of money building the largest/most powerful V-twin if there is no significant advantage. Since the chassis is most likely going to be custom, require it to accomodate adjusting the weight of the bike including rider. Bikes could be dynoed and weighed with riders prior to practice & qualifying. Top three finishers dynoed and weighed after the race.

  24. Don’t limit RPM. Just have a HP limit or various HP limited classes. Racers could spend what they like but in the end will be limited to their chosen HP limit.

    • A potential problem with letting racers spend what they like is that once they attain the HP limit or that of their chosen class, they will look for other ways to gain an advantage such as reducing weight. If they start building the frames or other components from ultra-lightweight uber-expensive unobtainium, then the price to be competitive spirals out of control. As mentioned above, handicap it to maintain as level of a playing field as possible. If done right you could even see people compete who are at a size/weight disadvantage.

    • Agree about too much standardization (although moto2 certainly has its fun moments even with the same engine).

      Here’s a great race as mentioned above:

      BTR Moto
      Buell (air cooled)
      Guzzis
      Vincent
      Wraith
      Ecosse
      +
      If someone can make the big air- cooled Japanese engines work (e.g. Gregg’s Customs)

      Ducati Sport Classic?

      “The Cooling Fin Series”. – celebrate the simplicity while they’re around

      • As much as I would like to see it, I doubt anyone would risk their Ecosse or Confederate “boutique” bikes. I doubt a Vincent would be competitve short of transplanting the engine into somethine like a BTR chassis with modern brakes, suspension, wheels, & tires. Someone may be brave enough to do it, but if I were fortunate to own any of those three, especially a Vincent, I wouldn’t dare.

        • Not the old Vincent. The one from Down Under that won the BoTT a few years ago. It is a modern version of the original, but true to its origin. Insane hp & torque in a compact bike

        • What would be cool to see would be companies like Ecosse and Confederate building track specials for a class such as this. Ecosse’s website still shows sketches of big-inch V-twin bikes reminiscent of the old KR-TT road racers.

  26. Just saw the recent post on Bike Exif, stating the new Confederate is worth $110,000. I dont get it, what makes it worth so much, I think the proposed class would bring bikes like this back down to earth. The smoke and mirrors that creates the illusion will be gone. Real money for real oerformance.

  27. That is a great video to watch, I blew it up on my screen and it almost felt like I was on the track myself

  28. Curt, are you planning on selling your transmission separately, or as a kit, including the frame?

  29. To Tony, not sure to what extent at this point. Right now I’m leaning towords a frame/tranny/swingarm/gas tank package. I think that would have the most value to the customer, everything outside of that would be easily obtainable from the aftermarket or from doner bikes. The other option would be to offer a complete bike, a new American sport bike.

  30. You’re entirely right, Jim, on all accounts, but … I still take a lot of satisfaction of having a smooth running engine after all those efforts 🙂
    I know, getting old, I guess, but to me it’s kinda part of the fun, too. \nPlus all my neighbors think I’m a sort of wizard and bring me their dead engines, while all it takes most of the time is just a cleaning of the carbs and new plugs … 😉

  31. Any of you ever hear of an XBRR?

    A reported 177HP at the wheel in a MASSIVE power curve. Big Twin my ass.

    FHD

  32. From what I read, that XBRR was not exactly reliable.

    Plus, Isn’t “Big Twin” used to describe the differences between what is now a HD Twin Cam vs. a Sportster? Similar to “big block vs. small block”