Racing monoshock frame

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I remember meeting Rob Tuluie at a Laguna Seca BOTT AMA national in the 1980s. We were in different classes so didn't race each other but we were both on Nortons. It was his very 1st roadrace. His previous experience was riding a vespa on the street. And he goes out and wins a National - amazing. He was so overwhelmed he could barely talk on the podium.

Another time - maybe at a later race at Laguna (can't remember), he was on a tricked out 920cc Commando with the isolastics so tight/hardned that he could barely hang on with the severe vibration caused by the heavy 920 pistons. His arms were cramping and he was in pain. The muscles of his forearms were visibly swollen. The frame might have cracked too (again can't remember for sure). He also broke a crank at a later race. I remember another friend/great racer -Fred Eiker who tried to tighten or eliminate the isolastics and ended up cracking his Commando frame. Lightweight pistons became a religion for me after that.
 
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Rob's bike had a fresh clean look when I met him but quickly got the development bike look. I thought he was going to school just for machine shop access but he was getting a phd in astrophysics. Did you see his later work? I'm sure he would say to us bike guys that he was giving F1 what we all know. If you throw your weight around you can make it do things its not supposed to and get away with it
https://mooregoodink.com/how-renaul...ampionship-by-creating-the-tuned-mass-damper/
 
jseng1 said:
I remember meeting Rob Tuluie at a Laguna Seca BOTT AMA national in the 1980s. We were in different classes so didn't race each other but we were both on Nortons. It was his very 1st roadrace. His previous experience was riding a vespa on the street. And he goes out and wins a National - amazing. He was so overwhelmed he could barely talk on the podium.

Another time - maybe at a later race at Laguna (can't remember), he was on a tricked out 920cc Commando with the isolastics so tight/hardned that he could barely hang on with the severe vibration caused by the heavy 920 pistons. His arms were cramping and he was in pain. The muscles of his forearms were visibly swollen. The frame might have cracked too (again can't remember for sure). He also broke a crank at a later race. I remember another friend/great racer -Fred Eiker who tried to tighten or eliminate the isolastics and ended up cracking his Commando frame. Lightweight pistons became a religion for me after that.
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Piston weight is always a factor when increasing capacity. What you pick up on the merry-go-round, you lose on the hurdy-gurdy ? A good 650 Triumph is probably better than any 750 Triumph - my friend has just found that out. His new 750 Triumph motor won't rev over 4000 RPM because of the vibration which froths the fuel in the carbs.
 
acotrel said:
Piston wemy friend has just found that out. His new 750 Triumph motor won't rev over 4000 RPM because of the vibration which froths the fuel in the carbs.
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There’s something very wrong with that Al, a box stock T140 will rev to 7k no trouble. Might rattle your fillings a bit whilst doing so, but it’ll do it!
 
Rob learned the hard way with full tilt but extremely unbalanced motors. I love learning from others mistakes.
Jim, I remember seeing the Monoshock Norton frame when internet first came out. I think you had a website early on and I think theres pictures on Michael Moores execellent old school webite http://www.eurospares.com/ Your in the same neighborhood so must know him. What i've learned is I'd never build or buy a racer Commando without bumming a ride on as many as I could before deciding what path to take. I hope we get to see more of the build going on
 
With racing motorcycles there are far more ways of getting things wrong than there are of getting them right. However, you learn from your mistakes. The best Triumph 650 I ever had on the road had a full race motor. The pistons were flat top and from a 350 BSA Gold Star - which had the edges of the crowns reshaped to fit the cylinder head and give squish. Those pistons were much lighter than standard Triumph pistons of the same comp. ratio, even though the gudgeon pins were of slightly larger diameter. The bike had wings - it was just all-round better. During my childhood I had several Triumphs with varyious compression ratios and piston weights.
My Seeley Commando 850 was a much easier build - I went almost straight to the answers. I just did what I needed to do, based upon experience.
 
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Every time an engine does a revolution, the pistons stop and reverse direction at the top and bottom of the stroke. Piston weight affects their inertia.
When I get rich, I am going to buy some of Jim Schmidt's light pistons and longer con-rods.
 
Actually, looking at a pics of the bike with fairing fitted, I’m guessing he has some kind of foam filter element built into the fairing around the intake mouth area...

Racing monoshock frame
 
More of the "those were the glory days" sort of stuff. I was fortunate enough to get to ride the Tularis around Willow Springs back in 2002, and it was quite an experience. Rob brought the bike out to a track day to give some of folks who had helped him in his efforts a chance to ride the bike. It was pretty impressive. This is a shot of me on the bike coming out of turn three. I'm admittedly not flogging it at full lean. I thought crashing Rob's baby might not be the smartest move I could make. But it was very impressive to ride.

Racing monoshock frame


This is a shot of us with the bike. Rob is the second from the left, and I'm the one on the right.

Racing monoshock frame


Ken
 
I have had difficulty following this thread. Does this bike have a Commando engine ?
 
There are three main things which affect a bike's handling - it's wheelbase, it's centre of gravity and it's steering geometry. If you get those right, not much else matters.
 
acotrel said:
There are three main things which affect a bike's handling - it's wheelbase, it's centre of gravity and it's steering geometry. If you get those right, not much else matters.
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That’s just plain wrong. Get those three things right, and stick none functioning forks or shocks on it, or shit tyres, and you’ve got a camel. Period.

In fact, I’d state with certainty that most poor handling bikes issues are due to my list of three and not yours.
 
Trellis frame looks like fun; might have to run in the superbike class with a mono shock and that wild swing arm but that’s ok, then you can run a big motor! Looks like it would be fun to throw a leg over but would need a bunch of handling sorting for sure- as Jim has run this set up, I am
sure he would be of assistance in this category. -Doug
 
Good to hear from you Doug.
I'm wondering if my frame would be legal in some classic racing as its been documented on the track since the mid-late 1980s. The plans include the earlier twin shock version as below. I had to enlarge the gas tank so I could wrap my body around it for support in the turns.

You can change out the shock mount plates to switch back and forth between twin or monoshock. Note the different bridge on the twin shock swingarm. Had to go to upswept pipes because I was dragging them.
Racing monoshock frame
 
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Fast Eddie said:
That’s just plain wrong. Get those three things right, and stick none functioning forks or shocks on it, or shit tyres, and you’ve got a camel. Period.

In fact, I’d state with certainty that most poor handling bikes issues are due to my list of three and not yours.
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Most of the battle lies in getting the bike to go in the right direction. Even if it is jumping around and sliding, it can still be quick. Too many people are tyre dependent. If you can ride really well, and your bike is set-up right, you don't use extreme angles of lean. The most hopeless situation when racing a Commando is when you join the procession at fill lean and play the power game. Much better to turn under, and out-accelerate from further back in corners..
 
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Nigel, my bike has ancient Ceriani forks, Komi shocks and very old tyres. Last time I raced, I rode under the three leaders at Turn 2 - who were all on 1100cc methanol fuelled CB750 Hondas. They were all out on the ripple strip at extreme angles of lean. That time my bike had a problem and stopped. If I race again, things will be different. Most race circuits are fairly smooth and if you are more upright in corners, you don't need much to get in front.

The problem with any of this stuff, is the cost of getting the bike handling right. The main expense is the cost of playing with fork yokes with different offsets to alter the trail.
As far as racing is concerned, you have an advantage over me. I was too old when I found out how to make a bike go fast in races. I never imagined how much difference getting the steering geometry right, actually makes.

 
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