HON­OR­ING BURT MUNRO, CEL­E­BRAT­ING SPEED

In­dian re­turns to Bon­neville 50 years later

Cycle World - - Munro Indian Race Watch - By Kevin Cameron

On the Bon­neville Salt Flats you stand on a mir­ror of pure white that will burn your skin from be­low while the arc-welder sun burns from above. Dark, jagged moun­tains sur­round it. But it’s flat. And big. A place to run for top speed.

In Au­gust of 1967, one-man R&D team Burt Munro, then 68 years old, streaked across that salt to set a 1,000cc record of 183.586 mph in his home­built stream­liner. It was pow­ered by an en­gine that be­gan as a 36.4ci 1920 In­dian Scout that he’d bought new. With his own hands he had made the OHV heads, cylin­ders, pis­tons, con­nect­ing rods, and cams of his en­gine, work­ing in a New Zealand shed that was his home for 27 years. He had set in­nu­mer­able records with it. That was 50 years ago.

At the end of 2016 Burt Munro’s son John and grand-nephew Lee Munro in­quired from In­dian in Min­nesota whether the com­pany planned any com­mem­o­ra­tion of this his­toric achieve­ment. The an­swer was, “Of course!” In Jan­uary 2017 came the go-ahead from the cor­po­rate pres­i­dent’s of­fice; a Scout-based Bon­neville racer would be built and Lee Munro—a com­peti­tor in Aus­tralian Su­per­bike—would ride it.

On Satur­day, Au­gust 12, 2017, Lee Munro rode a mod­i­fied mod­ern Scout to 191.286 mph on the rough and slushy Bon­neville short course, in the Mod­i­fied Par­tial Stream­lin­ing (MPS) 1350-G class. This was not an at­tempt at a stand­ing record. It was a prac­ti­cal recog­ni­tion of Munro’s ded­i­ca­tion to an ideal (his shelves of holed pis­tons and twisted con-rods bore the words “Of­fer­ings to the God of Speed”) and a re­newed com­mit­ment to striv­ing for ex­cel­lence.

The In­dian brand is more than 100 years old, and the suc­cess of Po­laris in re­viv­ing it is tes­ti­mony to its power—so many riders and oth­ers today had a fa­ther or grand­fa­ther who rode In­dian that the name is folk mem­ory. How did man­age­ment de­cide so eas­ily to con­tinue Munro’s Bon­neville quest? With­out con­tin­ued striv­ing and achieve­ment, the mem­ory would re­main just a big shape­less bag of left­over sen­ti­ment.

The ba­sis would be the Scout, whose en­gine is a liq­uid-cooled 60-de­gree V-twin of 99.0 x 73.6mm bore and stroke for 1,133cc, with four valves per cylin­der op­er­ated by chain DOHC. The limit of the Bon­neville class cho­sen was 1,350cc. To get closer to that a whack­ing great 7mm over­bore took the cylin­ders to 106mm and dis­place­ment to 1,299cc (79.3ci).

This is a cruiser en­gine, right? So what’s it do­ing with a sport­bike’s four valves and dou­ble over­head cams? In twovalve cruiser en­gines the key to mighty bot­tom-end torque is short valve tim­ing, but as they rev up, that short tim­ing lim­its air­flow, caus­ing torque to slope down with ris­ing rpm un­til they wheeze out at around 5,000 rpm. But what if you’ve rid­den other kinds of bikes and like that feel­ing of winged power that sails with­out strain to higher revs and real horse­power? The only way to com­bine the short tim­ing that makes torque down low with enough air­flow for power up higher is with a very light four­valve-per-cylin­der valve train. That is the essence of In­dian’s Scout—it has it all.

When you plan for Bon­neville you need sev­eral things. One is power—the power to over­come aero drag that rises as the cube of ve­loc­ity. Another is re­li­a­bil­ity— too many teams “go to blow” be­cause their pow­er­plants are frag­ile at the nec­es­sary power level. Af­ter the fact it’s ro­man­tic to re­mem­ber all-nighters spent un­der the stars in the glare of head­lights, putting another $10,000 worth of parts into a blown en­gine. Bet­ter by far to have an en­gine that does what you need it to do eas­ily. The last big­gie is trac­tion. Even at the best of times grip on the salt is

maybe 40 per­cent of what it is on nearby In­ter­state 80. It can also be wet, slushy, and rough. Then there are de­tails like stream­lin­ing or mak­ing sure your electrics aren’t shorted by the salt that has caused so many ef­forts to sput out.

The stated aim of the In­dian crew was to honor Burt Munro and say, “We’re here!” but I have a sus­pi­cion that what they re­ally wanted was to hit 201 mph.

Horse­power. First was more dis­place­ment—the 7mm over­bore. There’s no point in go­ing big if you can’t de­liver the nec­es­sary ex­tra air­flow. The ob­vi­ous path was big­ger valves (in­takes are now 42mm, ex­hausts 36), but the valve guide lo­ca­tions cor­rect for a 99 bore were too close to­gether for big­ger valves— crowd them and cylin­der heads crack be­tween the two ex­haust seats or from plug hole to ex­haust, un­less there’s enough metal be­tween.

Another prob­lem: stock in­take ports. They look as though Keith Duck­worth (hon­ored fa­ther of in­take down­draft) be­gan to draw mod­ern ports but had to take a phone call. While he was out of the room, some­body else de­cided, “We need to put a sin­gle throt­tle body in the cylin­der vee to feed both, so we’ll just bend th­ese ports hor­i­zon­tal…”

As the late “Heavy Chief of Air­flow,” Kenny Au­gus­tine, liked to say, “Air can ei­ther go fast or go around corners. But it won’t do both.” That meant In­dian’s en­gi­neer­ing team needed to not only re­lo­cate valves but straighten new in­take ports. How about we just do new heads?

Those engi­neers cre­ated this project on their own time. When I asked how they all hap­pened to vol­un­teer, I was told, “How of­ten do you get the chance to do a project like this us­ing the lat­est re­search equip­ment? AVL cylin­der pres­sure in­di­ca­tors, in­stru­mented dynos, sen­sors…?”

Okay, I get it. This meant those in­take ports weren’t just drafts­man’s art. They were also known in de­tail through sim­u­la­tion and mea­sure­ment. MOTEC en­gi­neer James Whisler talked about the sub­tle ef­fects of long ver­sus short fuel-in­jec­tor duty cy­cle and how ei­ther is af­fected by in­jec­tion tim­ing. The more you can mea­sure, the more po­ten­tial con­trol

strate­gies you dis­cover.

“You don’t want to spray the fuel on the port wall be­cause so much will evap­o­rate that the re­sult­ing va­por dis­places some of the air­flow,” he said.

You can’t say that un­less you can ac­tu­ally mea­sure and un­der­stand what’s go­ing on.

A twin-bore down­draft (Ford) throt­tle body com­pleted the in­take side. A sin­gle show­er­head in­jec­tor? Mm, maybe not; high-flow oper­a­tion is good but snap re­sponse? Not so good. So a sin­gle in­jec­tor was added un­der each but­ter­fly.

The re­sult at this point is 175 hp at 9,100 rpm, with peak torque down at 7,300. They talked about their torque curve—a ta­ble, flat from edge to edge, just like the torque of In­dian’s FTR750 flat­tracker. That is made pos­si­ble by mod­er­ate valve tim­ings, four valves, and large valve lifts. Plenty of torque down low be­cause short tim­ings pre­vent in­take back­flow. Torque con­tin­ues into high revs be­cause there’s plenty of air­flow cross-sec­tion.

When the en­gine was warmed up on Satur­day, its sta­ble, reg­u­lar

idle told my ears that valve tim­ing is not “Top-end-only Bon­neville Su­per-stomp.” I would hear plenty of rad­i­cal rumpity-rump idle from the two-valve V-8s warm­ing up around us. All the con­trast­ing sounds and what they tell are just another rea­son to be on the salt.

Low grip on salt means get­ting to full throt­tle takes time. I watched more than one su­per­charged road­ster get to sec­ond gear, show white be­hind the right rear tire, and then snap side­ways an in­stant later, forc­ing the driver to lift. A 400-mph “liner” para­dox­i­cally be­came much louder the far­ther it went away from us.

Once at speed the con­di­tions are more se­vere by far than the Day­tona bank­ing. Full throt­tle for miles. There­fore have a look at the big alu­minum tim­ing cover on the right side of the Scout’s en­gine. See that stain­less braided oil line? It sends oil past a lip seal, straight into the end of the crank, fresh from the oil fil­ter. Drillings in the crank carry it to the crankpin. End-feed­ing the oil (rather than con­ven­tion­ally tap­ping it from the ad­ja­cent main bear­ing, au­to­mo­tive style) means “cen­trifu­gal force” works for you, not against you. A re­li­able low-fric­tion oil film is the re­sult—even though it might be less than 2 mi­crons thick in the loaded zone (0.00008 inch). Burt Munro, too, had switched his stream­liner’s crankshaft to end-feed.

Re­cip parts are Car­rillo rods and CP forged two-ring pis­tons.

The stock Scout has pis­ton cool­ing oil jets and so does this Bon­neville spe­cial. The bot­tom end is stock: stock bear­ings, stock case, gear­box, and clutch (oh, yes—stronger springs). I had the op­por­tu­nity to talk with sev­eral of the engi­neers Satur­day evening. They told me the work they’d done and the un­der­stand­ings they’d achieved would be valu­able in sev­eral other pro­grams In­dian is run­ning.

“Does this mean the Scout en­gine might not be a cruiser for­ever?”

“Could be,” was the enig­matic an­swer.

What con-rods did Burt Munro run? In­dian’s orig­i­nals were de­signed for 11 hp. He sawed and filed a set of steel ones from a truck axle, last­ing 20 years (his “ma­chine shop” con­sisted of a My­ford lathe, straight out of the pages of Trustee from the Tool­room).

Back to the present! The 2017 Scout is low­ered about 3 inches, with the orig­i­nal rear sus­pen­sion units re­placed by struts. An off-the-rack Airtech fair­ing (is that a Char­lie Toy?) was nar­row at the front so the team made nar­rowed fork crowns and the bars were nar­row, turned straight down. Rider Lee Munro said the bike was su­per sta­ble at El Mi­rage, where on July 19 this year it went 186.681 mph.

“You get too ag­gres­sive, it’ll fight back,” he said. “I think of a bike as like an an­i­mal. I sug­gest; I don’t force it. Here, the cen­ter of the course is like slush, like melted snow. And it’s very rough, lot of holes, lot of bounc­ing.”

What would hap­pen Sun­day? Could Lee reach higher speeds with the longer ac­cel­er­a­tion af­forded by switch­ing to the long course? You get in line with the oth­ers and move up as the runs are made. Ahead of the In­dian a cou­ple of places was a 220-mph diesel high­way trac­tor, pow­ered by an MTU V-16 taken from a min­ing truck, mak­ing thou­sands of horse­power. En­gines start­ing, lopey idles. Where else could you see a ’32 Road­ster with a down­force-

pro­duc­ing ven­turi un­der­body and an in­ter­nal-com­pres­sion en­gine in­take dif­fuser?

The In­dian starts and warms up. Re­li­able oper­a­tion, sharp sound, pro­fes­sional re­sponse. Munro gets aboard and goes— no muss, no fuss. A dis­ap­point­ing 186.415 mph. Later some­one comes to the door of the mo­torhome and asks en­gi­neer James Whisler, “Are you… Will they make another run this af­ter­noon?”

Whisler, look­ing up from the many data traces on his lap­top screen, points out the win­dow.

“See that flag over there? As long as it’s pointed up-course there’s no point in another run.”

He ex­plained that Satur­day there had been a 1- to 2-mph tail­wind and today it was a 10-mph head­wind. Plus the air’s thin­ner today—den­sity al­ti­tude yes­ter­day was 4,800 feet, but now it’s a gasp­ing-for-breath 6,000. Teams in turbo classes can dial up their boost to det­o­na­tion’s doorstep and have power, but the In­dian’s at­mo­spheric in­duc­tion makes its power pro­por­tional to air den­sity. There’s no point in fight­ing physics. Physics wins.

In­dian today has some­thing Burt Munro did not: reams of data, gath­ered by the sen­sors that cover the ma­chine, re­ported to the lap­top through a USB ca­ble plugged into the bike be­hind the rider’s left thigh. This is grand be­cause it re­veals things you’d never think of, but in­ter­pret­ing the data is a mine­field.

“Ev­ery sen­sor you use is just a lie, an ap­prox­i­ma­tion of the real world,” Whisler said. Ev­ery sen­sor has a re­sponse time and a sam­pling rate. Think about it. If sam­pling rate comes close to en­gine fir­ing fre­quency, strange “trends” can ap­pear that are just ar­ti­facts of the sys­tem. False in­for­ma­tion. This is not push-but­ton “com­puter rac­ing” but re­quires hours of star­ing at the data (just as the old-timers stared at spark plugs), try­ing to ex­tract the real mean­ing.

What next? The engi­neers gath­ered valu­able data and I sus­pect the han­ker­ing for 201 mph goes all the way to the pres­i­dent’s of­fice. As Burt Munro used to say, “You just need one good run…”

Burt’s son John Munro con­grat­u­lates Lee Munro, Burt’s grand-nephew, on ob­tain­ing his SCTA li­cense at El Mi­rage, Lee’s first crack at land-speed rac­ing. GEN­ER­A­TIONS:

Speed runs are punc­tu­ated by a many-mile run back to the pit area. Chal­leng­ing con­di­tions in later runs— wind and de­te­ri­o­rat­ing salt—led to head­shake and other prob­lems in the 180mph range. JOUR­NEY BACK:

PRIN­CI­PALS: John Munro is well aware of his fa­ther’s grand legacy and was in­te­gral to The

World’s Fastest In­dian film. In fact, he shared that the ti­tle came from one of Burt’s tro­phies awarded by SCTA. Wayne Kolden (right) is a land-speed racer who also hap­pens to head up “en­gine cal­i­bra­tion” at In­dian and was charged with lead­ing this af­ter­hours rac­ing pro­gram.

Lee Munro tries on the In­dian Scout Munro Spe­cial replica built for The World’s

Fastest In­dian. It’s nar­rower and more stretched out than even the Spirit of Munro mod­ern Scout racer. EX­TREME LINER:

Burt Munro atop an ear­lier ver­sion of his 1920 Scout stream­liner (body off) in 1962. Pho­tos above show the bike in 1953 at Oreti Beach, New Zealand, where Munro reached 123.831 mph. Mod­ern Scout pow­er­plant with stain­less ex­hausts. It sounds crisp. IT­ER­A­TIONS:

The 2017 In­dian Land­speed Rac­ing crew, work­ing on their own time af­ter hours to get the Scout to the salt (from left to right): Neil Sikora, Gary Gray, Lee Munro, James Whisler, Steve Tittl, Matt Graser, Dan Ger­vais, Brenna Matthies, Todd Matthies, and Wayne Kolden.

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