80 HP at 8700RPM by Herb Becker

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Hey John; Yes, Herb machined my crank from a chunk of billet steel- if you look at the photos of it, you obviously have seen a slight line along the edge of the bob weight- when he sent it out for hardening, a small crack developed on the end with the bob weight. The steel guy blamed the hardening guy, the hardening guy blamed the steel- all offered a new chunk of steel and free hardening but no recompense for the insane number of hours it takes to machine one of these. So, Herb elected to just cut the bob weight section off and machine a slide on portion that bolts up with a couple big allen bolts. It is still as tough as a one piece and in theory you switch out the bob weight section to change the weight. If you look at the photo, there is a small ' T ' section that the bob weight slides onto, easy to see in this pic- the allen bolts come up from below-

80 HP at 8700RPM by Herb Becker
 
Doug, are you willing to share with us what cam and follower set up you are using, or is this a race secret?
 
Nice crank , Doug , zoomed into see the dovetail fit up.
My new one piece uses a circular hollow centered flywheel, with removal bob weights that fit inside the flywheel and bolt up tight

Regards Mike
 
Fast Eddie said:
Alan, we know you love your long stroke (as I do mine) but if your running a stock spec motor you'll be lucky if its putting out over 40 RWHP. So no matter how you look at it, and no matter what 'margin of error' is in the dyno reading, there ain't no way you'd keep an 80+RWHP Commando in sight for long!

You might catch a glimpse every few laps as he came past you though...!
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O that's just mean
 
We have methanol-fuelled 1100cc CB750 Hondas to race against. The last time I raced I was beside the leader coming out of turn 2 on lap 1 when the fuel line came off and doused the motor with methanol. Talking about going fast is not the same as doing it. My 850 is fast enough to win against four cylinder bikes, particularly in the wet - I am experienced enough to know that. However I would never take it to a 'power circuit' such as Phillip Island.
I raced my 63mm stroked 650 Triumph engined Triton for 12 years when I was a kid and I learned how to stay alive. On occasion I was well up in the lead bunch in races and was even out in front on occasion when I was competing against B and C graders on Z900 and H2 Kawasakis. The worst thing about the short stroke motor was if I ever got balked and found myself going too fast to change down. Then it depends on the motor pulling hard. The same thing happens when you turn into the wind with a 250cc Yamaha engined two stroke. They feel as though they have stopped.
During my life I've had about 12 650cc Triumphs both Tribsas and Triton and I've ridden what was probably the best 650cc Triton here in the 70s - The Seeley has 200cc capacity advantage, however I still would not have expected it to be as good as it is.
About the 40 rear wheel horsepower - it is irrelevant what the actual power figure might be as long as the commando engine pulls like a train. When you start revving a commando engine above 7000 RPM to get more power, the law of diminishing returns always applies.
 
Thanks Doug. Sorry to hear about the trials and tribulations of the heat treating but it looks like a solid recovery of the crank. When I noticed the separate bob weight it reminded me of some Lycoming aircraft engine crankshafts where bob weights are held in place by steel pins and clips. You could hear them rattle upon start up and shut down. I think the bob weights on pins had something to do with harmonics.

I also note the broad torque curve Herb achieved which looks better and broader than most high preformance long stroke Norton's I have seen. So where are you and Herb taking this build from here? Any more to gain by finessing the intake and exhaust, different cam etc?

And finally, what race venues are you and Herb targeting this year? I'd welcome having a go at it with you at Barber if I can manage my way around (not through :D ) traffic the next time there.
 
Hey Fast Eddie, cam is a Megacycle triple s and lifters are BSA. Herb thinks this is a very mild cam but because the head is so good, it seems to work well.

John, amount of racing always depends on what I can afford... for sure I will be at Mosport and Barber, I would like to do more, at least another weekend in somewhere, not sure where. I won't be at Mid-O (or New York) this year as I have a 3 week job around the beginning of July in Kenya. Just got an email from BikeEXIF, they are using two of my photoshoots for their upcoming calendar, Kenny's Sunburst Norton and the Walt Siegl MV Agusta I shot while at Barber last year, very happy about that.

No more motor playing about for a bit, the most important upgrades I still need are Maney cases and a TT box- that 5 speed I hate to tell Herb is holding me up more that anything but is not in the budget.
 
'I also note the broad torque curve Herb achieved which looks better and broader than most high preformance long stroke Norton's I have seen. So where are you and Herb taking this build from here? Any more to gain by finessing the intake and exhaust, different cam etc?'

Perhaps all the long stroke Norton's you have seen have had silly port jobs and used cams designed for top end rather than mid-range ?
 
Doug MacRae said:
Hey Fast Eddie, cam is a Megacycle triple s and lifters are BSA. Herb thinks this is a very mild cam but because the head is so good, it seems to work well.

John, amount of racing always depends on what I can afford... for sure I will be at Mosport and Barber, I would like to do more, at least another weekend in somewhere, not sure where. I won't be at Mid-O (or New York) this year as I have a 3 week job around the beginning of July in Kenya. Just got an email from BikeEXIF, they are using two of my photoshoots for their upcoming calendar, Kenny's Sunburst Norton and the Walt Siegl MV Agusta I shot while at Barber last year, very happy about that.

No more motor playing about for a bit, the most important upgrades I still need are Maney cases and a TT box- that 5 speed I hate to tell Herb is holding me up more that anything but is not in the budget.
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Thanks Doug, the SSS cam is about the same as a 4S isn't it? If so, not what most folk would call overly mild! But it is designed for 3" radius lifters isn't it? So you are reducing the duration significantly by using BSA followers and I guess that's helping your broad spread of power.
 
Doug,
A friend of mine, now deceased was CEO of our local raceway. He once commented that many people do not recognise what business we are in. I suggest it is the entertainment business. The big costs in racing in Australia lie in licence and entry fees. As long as we race simply for the fun of it without recognising the need to supply the spectacle of quality racing for our customers, the guys who compete will always pick up the tab. I've long been on the band-wagon about developing better race classes - perhaps based more on technology and capacity similarities than the date of machine manufacture which is the current popular approach. I cannot see a problem with racing commandos in a class designed for air-cooled four-stroke two-valve engine twins of up to 1000cc. To my mind the Paul Smart Replica Ducati is the same sort of old garbage as the commando.
I never saw BOTT, however it must have been lovely until the four-valve water-cooled Ducatis dominated. I suggest that is probably the way to pull a decent crowd.
 
The same day we ran my race bike on the dyno, Herb put Andy's Bonneville Norton on as well. He did much of the work and all the motor and trans work. Bike is a 750 short stroke with a Fullauto head running a Triumph crank. It put out a solid 75hp at the rear wheel.
Andy is the the tall bloke on the right, Herb on the left.

80 HP at 8700RPM by Herb Becker
 
Cool bike. Looks well set up for the salt. Has it been to Bonneville before, or is this a new effort? What class does he plan to run? Looks like it could run as is in 750-M-PG, if the wheelbase hasn't been stretched more than 10% over stock. Current records are 137.872 mph with SCTA and 159.903 mpg with AMA. 75 hp should certainly get him past the SCTA record, but probably not enough for the AMA record. That one was set by Tom Mellor with his triple back when you could get away with some serious tail section streamlining in the unstreamlined class. They don't allow that anymore, so his record is probably pretty secure. Back in 2001 I managed to get a class record with SCTA at 131.113 mph with a long stroke 750 making 61 rwhp, so 75 hp should definitely be enough to get past the current record. We didn't get to run at all last year, because the salt conditions were so bad that all the meets were cancelled. Hopefully we'll be luckier this year.

Ken
 
Doug MacRae said:
The same day we ran my race bike on the dyno, Herb put Andy's Bonneville Norton on as well. He did much of the work and all the motor and trans work. Bike is a 750 short stroke with a Fullauto head running a Triumph crank. It put out a solid 75hp at the rear wheel.
Andy is the the tall bloke on the right, Herb on the left.

80 HP at 8700RPM by Herb Becker
Click to expand...

Whats interesting is how similar John and Dougs motors are. Both are short strokes with Full auto heads and lightweight domed pistons (although Dougs has a bathtub chamber and the stroke is 1.6mm shorter). When Dougs bike is fitted with the 39mm carbs they have nearly the same output and torque - within a couple HP I think. Small wonder since Herb build each of them and they probably have similar ports, intake length, compression etc.
 
Just so everyone can appreciate the broad torque base this short stroke motor of Doug's puts out I have presented data from a few engines as benchmarks for comparison. I've pick +50 ft-lbs torque as a threshold in which to express range in rpm as it is about the max for a well sorted out Commando for the street so hopefully most can relate to this number. I've read off of Doug's dyno chart as well as from a few other dyno charts including a Nourish NRE eight valve long stroke tuned and prepared by Dave Nourish as well as a long stroke 750 campaigned a few years ago by one of the list members some of us are familiar with on this forum (w/o silly port and cam). All motors are nominal 750 cc displacement (except the 1,007 cc thrown in for fun) and all but the short stroke and 1,007 cc have comparable long strokes.

Description_______________Lower rpm_______Upper rpm________Range rpm
Long stroke race Norton_____4,350___________6,550____________2,200
NRE _______________________4,800___________7,500____________2,700
Doug's Short Stroke_________4,400___________7,800____________3,400
1007cc_____________________3,700___________Well Past red line___+?

As another benchmark, a Commando I raced many years ago that was thrown together with a mild cam (Megacycle 560-020) around 10.5:1 compression with open pipes, megaphones, decent valve seat job and 32mm AMAL carbs and it barely broke 50 ft-lbs torque. As in the case of Doug's short stroke, best as I can tell from reading off of his graph he has +50 ft-lbs torque from 4,400 rpm to 7,800 rpm for a range of 3,400 rpm. Other than the 1,007cc engine, Doug's engine eclipses the bench mark engines shown. Furthermore, the peak torque of Doug's short stroke is above 60 ft-lbs torque for 1,000 rpm. Neither the Nourish nor the long stroke race Norton shown comes close to that. That is an exceptional build. It does not even come down to math but something much simpler such as a number line where a short stroke motor has a longer number line (rpm range) to work within.

This short stroke of Doug's is truly a broad ranged torque monster when compared to a few good benchmark long stroke race engines.
 
Dances with Shrapnel said:
Just so everyone can appreciate the broad torque base this short stroke motor of Doug's puts out I have presented data from a few engines as benchmarks for comparison. I've pick +50 ft-lbs torque as a threshold in which to express range in rpm as it is about the max for a well sorted out Commando for the street so hopefully most can relate to this number. I've read off of Doug's dyno chart as well as from a few other dyno charts including a Nourish NRE eight valve long stroke tuned and prepared by Dave Nourish as well as a long stroke 750 campaigned a few years ago by one of the list members some of us are familiar with on this forum (w/o silly port and cam). All motors are nominal 750 cc displacement (except the 1,007 cc thrown in for fun) and all but the short stroke and 1,007 cc have comparable long strokes.

Description_______________Lower rpm_______Upper rpm________Range rpm
Long stroke race Norton_____4,350___________6,550____________2,200
NRE _______________________4,800___________7,500____________2,700
Doug's Short Stroke_________4,400___________7,800____________3,400
1007cc_____________________3,700___________Well Past red line___+?

As another benchmark, a Commando I raced many years ago that was thrown together with a mild cam (Megacycle 560-020) around 10.5:1 compression with open pipes, megaphones, decent valve seat job and 32mm AMAL carbs and it barely broke 50 ft-lbs torque. As in the case of Doug's short stroke, best as I can tell from reading off of his graph he has +50 ft-lbs torque from 4,400 rpm to 7,800 rpm for a range of 3,400 rpm. Other than the 1,007cc engine, Doug's engine eclipses the bench mark engines shown. Furthermore, the peak torque of Doug's short stroke is above 60 ft-lbs torque for 1,000 rpm. Neither the Nourish nor the long stroke race Norton shown comes close to that. That is an exceptional build. It does not even come down to math but something much simpler such as a number line where a short stroke motor has a longer number line (rpm range) to work within.

This short stroke of Doug's is truly a broad ranged torque monster when compared to a few good benchmark long stroke race engines.
Click to expand...

Interesting comparison John and I agree, Doug's torque spread is indeed impressive.

It prompted me to look at my own, and mine peaks at 50ft lbs! However, it produces over 46ft lbs from 3300 to 6200rpm.

The Maney exhaust system changed this to 51ft lbs from 4500 to something over 6500.

I reckon Doug's high CR is helping him out a lot along with the fact he is using a relatively 'mild' cam (his words).

I am keen to see what mine will be like with the Comnoz reworked RH10 fitted.

For ref, mine is an 850 with 10.5:1CR JS pistons and rods, JS1 cam kit, 35mm FCRs, stock pipes without balance pipe and stock peashooters.
 
My torque is low 60"s with a long stroke motor with only 0.040" over from a standard bore , 10:1 , mild cam , RH10 head with standard Vv's, the torque allows me to pull a tall 1st gear in a TTI close ratio 5 speed.
This a race motor.
80 HP at 8700RPM by Herb Becker

Regards Mike
 
Brooking 850 said:
My torque is low 60"s with a long stroke motor with only 0.040" over from a standard bore , 10:1 , mild cam , RH10 head with standard Vv's, the torque allows me to pull a tall 1st gear in a TTI close ration 5 speed.
This a race motor.
80 HP at 8700RPM by Herb Becker

Regards Mike
Click to expand...

That's also a nice and wide spread of power and torque you have there Mike. For the benefit of the viewers Mike, your 'mild' cam is a JS2 is it not?

That's a shade hotter than my JS1 and I do wonder if its part of the reason for your stronger output over 4,500rpm.
 
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