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Made some more progress this weekend, got the rear disc brake mounted up along with steering stops and clipons/ levers mounted up. Also got the triple trees fully mounted after making up some spacers and a shouldered nut to preload the bearings prior to installing the top tree. Waiting on some 15mm ID spacer pieces to arrive so the rear axle can be finalized. now just need to set the empty cases in the frame with a GB sprocket so measurements can be made for rear sprocket spacing. Need to starting looking into seat type and some sort of gas tank. Maybe a small bobber/ chopper type tank I can cut and rework to lower/ narrow but still hold ~ a gallon.

LSR22.jpg LSR23.jpg LSR24.jpg

1955 BSA Bantam D1 Plunger
1956 BSA A10RR Street and LSR Bike
1961 BSA C15S
1966 BSA Lightning
1966 BSA Spitfire - Soon to be an A50 Powered LSR Bike
1969 Triumph T100C
1970 Triumph TR6R
1970 Triumph TR6C
1972 BSA Lightning LSR Bike
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Chris, I can offer a naked frame Triumph as an an example...On the earlier dyno runs,my 650 made 55 rwhp at 7100 rpm and 46 ft lbs torque at 5100 rpm. At 7100 rpm the engine stll had 39 ft lbs torque before it fell off rapidly...Later on it made a few more HP.....On the track it was running 7400 rpm for best speed. I did not explore this and possibly higher speeds were possible if the bike was geared for less rpm........


61 hot rod A10, 89 Honda 650NT .On a bike you can out run the demons
"I don't know what the world may need
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Think I'll drive to find a place, to be surly"
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Chris, horsepower is what gets the job done in land speed racing. torque is just the amount of force at any given rpm, but hp is the rate of doing work. You will get your maximum speed when you are at your maximum horsepower. In landspeed racing, that point will be when your gearing is such that you achieve your maximum horsepower at the aero wall, that is when the total drag force and horsepower are equal. So you want to keep reving that motor until you get to your maximum hp rpm. If your maximum hp rpm is at 8,000, that is the rpm you want to see at the speed traps. If you can't get to that rpm, then lower your gearing. If you're able to exceed that maximum hp rpm, then raise your gearing.

Of course, you may not be able to get to that aero wall if your hp band is so small that shifting from 3rd to 4th (on our 4 speed trannies) drops you down so far on the hp curve that you're hitting a lower aero wall because your horsepower is lower. It happened to me at Bonneville with my 250. Shifted to 4th gear at 87mph and not enough horsepower at the lower rpm in 4th gear to continue to accelerate. I added two teeth to the rear sprocket which meant I was at a slower speed when I shifted to 4th, but enough hp to continue on up to my maximum hp rpm, which was around 8200 rpm.

Tom

Last edited by koncretekid; 10/03/22 3:50 pm.

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Originally Posted by koncretekid
Chris, horsepower is what gets the job done in land speed racing. torque is just the amount of force at any given rpm, but hp is the rate of doing work. You will get your maximum speed when you are at your maximum horsepower. In landspeed racing, that point will be when your gearing is such that you achieve your maximum horsepower at the aero wall, that is when the total drag force and horsepower are equal. So you want to keep reving that motor until you get to your maximum hp rpm. If your maximum hp rpm is at 8,000, that is the rpm you want to see at the speed traps. If you can't get to that rpm, then lower your gearing. If you're able to exceed that maximum hp rpm, then raise your gearing.

Of course, you may not be able to get to that aero wall if your hp band is so small that shifting from 3rd to 4th (on our 4 speed trannies) drops you down so far on the hp curve that you're hitting a lower aero wall because your horsepower is lower. It happened to me at Bonneville with my 250. Shifted to 4th gear at 87mph and not enough horsepower at the lower rpm in 4th gear to continue to accelerate. I added two teeth to the rear sprocket which meant I was at a slower speed when I shifted to 4th, but enough hp to continue on up to my maximum hp rpm, which was around 8200 rpm.

Tom
Tom,

My previous reply, I was basically mentioning similar to you here. If peak HP is reached at 8k then there is no reason to run it any higher but making sure it achieved when approaching the timing traps. I will mentioned I think torque does play a role in our sport as well. My stroker A65 has 60lb.ft.torque and 65hp and when running at Wilmington with 3rd gear popping out at 4500rpms and shifting into 4th, the higher torque numbers and broad power curve pushed through the drop in RPM's short shifting into 4th caused to help achieve 134mph (now if we can have the winds cooperate at Loring with a fully working GB...), if my torque numbers were lower Im pretty sure I wouldnt have been able to power through the drop in RPM even with 65HP. The camshaft I chose should help aid this 500cc have power up around 7000 at least so I am hoping the torque/ HP curve will be good and not really spikey. Another thing to consider is fuel flow and not delivering enough to gain speed but a mechanical fuel pump should be able to take care of that.

I havent given too much thought on the gearing just yet but Im thinking of a 20/ 41 combo right now which puts me pretty close to the record speed wise and we can adjust from that point but will need to know the power curve first to be accurate.


1955 BSA Bantam D1 Plunger
1956 BSA A10RR Street and LSR Bike
1961 BSA C15S
1966 BSA Lightning
1966 BSA Spitfire - Soon to be an A50 Powered LSR Bike
1969 Triumph T100C
1970 Triumph TR6R
1970 Triumph TR6C
1972 BSA Lightning LSR Bike
1974 Triumph T150V
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Made a bit more progress over the weekend. Got the engine mocked up in the frame and shift linkage setup. I may fabricate some foot peg mounts to push them back 4" but this will be dependent on how I feel once my seat/ tail section arrives.

LSR25.jpg LSR26.jpg

1955 BSA Bantam D1 Plunger
1956 BSA A10RR Street and LSR Bike
1961 BSA C15S
1966 BSA Lightning
1966 BSA Spitfire - Soon to be an A50 Powered LSR Bike
1969 Triumph T100C
1970 Triumph TR6R
1970 Triumph TR6C
1972 BSA Lightning LSR Bike
1974 Triumph T150V
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Made some cylinder tank templates to visualize how they would fit and work trying to achieve a tight tuck, so far they seem to be the right sizing but will finalize once my seat/ tail section arrives. Slowly progressing.

LSR29.jpg LSR28.jpg
Last edited by Blown Income; 10/14/22 4:30 pm.

1955 BSA Bantam D1 Plunger
1956 BSA A10RR Street and LSR Bike
1961 BSA C15S
1966 BSA Lightning
1966 BSA Spitfire - Soon to be an A50 Powered LSR Bike
1969 Triumph T100C
1970 Triumph TR6R
1970 Triumph TR6C
1972 BSA Lightning LSR Bike
1974 Triumph T150V
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my machine is really similar to tonys

if i gear for 135 mph at 7275, winding the 3-4 shift to 8500, i can pull 135.

if i gear for 138 at 7275, still winding, i drop out of the goldilocks zone and peak at 121.

at least thats what happened when i raised the gearing looking for a boost from the Q16 oxygenated fuel.

im right at the peak of horsepower, i think, and betterv aero is my only hope for going faster. but i dont fold up like i used to. 140 mph may be in the cards for one of my skinny kids, but probably not for their fat and creaky father


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I encountered something similar on my bike this year as well with the gearing (headwinds probably didnt help), I was really curious how the Q16 worked out for ya. Have you given any thought to added nitrous or even switching to a heavy Nitro mix? I've been trying to convince my better half for years she needs to take over as rider. Better power to weight ratio, can achieve a better tuck than I can ever hope for but so far no luck. Maybe my youngest daughter will carry the torch in 10yrs???


1955 BSA Bantam D1 Plunger
1956 BSA A10RR Street and LSR Bike
1961 BSA C15S
1966 BSA Lightning
1966 BSA Spitfire - Soon to be an A50 Powered LSR Bike
1969 Triumph T100C
1970 Triumph TR6R
1970 Triumph TR6C
1972 BSA Lightning LSR Bike
1974 Triumph T150V
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Well time slipped away but finally got my gas tank fabricated and partially mounted to the chassis, need to finish a few welds and detailing along with pressure testing for leaks but the shape is nice and flows well and also provides ample room to lay as flat as possible. Both tanks combined hold 1 1/2 gallons so just snuck over the minimum required. Got my Air-Tech seat/ tail section too but it doesn't fit like I was expecting so back to the drawing board. Thinking of cannibalizing's an extra stock A65 seat and modifying into a clubman type without the padding. Hoping to have the seat wrapped up in the next week so I can get the bike torn down, engine sent out for machine work and get the chassis parts cleaned up, painted and ready to run by spring.

LSR30.jpg LSR32.jpg LSR31.jpg

1955 BSA Bantam D1 Plunger
1956 BSA A10RR Street and LSR Bike
1961 BSA C15S
1966 BSA Lightning
1966 BSA Spitfire - Soon to be an A50 Powered LSR Bike
1969 Triumph T100C
1970 Triumph TR6R
1970 Triumph TR6C
1972 BSA Lightning LSR Bike
1974 Triumph T150V
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nice work on the tank mounts. mine are held on with my own toothpaste-tube style of welding . . .

i love the BSA watermelon motors. theyre so 1960s space-age looking, you know?

the Q16 didnt give me anything that C12 didnt already provide, except an eye-popping understanding of huge jet sizes. im really interested in plain gas, though so nitrous isnt in the cards soon, for me. im less interested in absolute speed than i am with going fastest within absurd self-imposed limitations.


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Gonna be great to have another Beezer out there. Lookin' good!

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Looking good, Chris! You know if you just need 1 more mph, you might be able to find a smaller rider at Loring.....................Just saying.

I'm curious to know which air-tech seat you ordered, as I'm considering one for my TR25 MPS bike I run at Bonneville. There's just one record above my 99.6 mph record that is about 1 mph above mine and that bike had a full fairing (I'm only using a Dunstall type front fairing on mine currently.)

Tom


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Originally Posted by koncretekid
Looking good, Chris! You know if you just need 1 more mph, you might be able to find a smaller rider at Loring.....................Just saying.

I'm curious to know which air-tech seat you ordered, as I'm considering one for my TR25 MPS bike I run at Bonneville. There's just one record above my 99.6 mph record that is about 1 mph above mine and that bike had a full fairing (I'm only using a Dunstall type front fairing on mine currently.)

Tom
Tom, this 500 may need all the extra help possible to pull off a 124mph run....

I order the modified Moriwaki seat but just wasn't happy with how it fits/ looks on the bike, the kicker was waiting 10wks to receive only to conclude it isn't for me. Its a bit wide in the front but may work better on a faired bike.

MORI1M.jpg

1955 BSA Bantam D1 Plunger
1956 BSA A10RR Street and LSR Bike
1961 BSA C15S
1966 BSA Lightning
1966 BSA Spitfire - Soon to be an A50 Powered LSR Bike
1969 Triumph T100C
1970 Triumph TR6R
1970 Triumph TR6C
1972 BSA Lightning LSR Bike
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Originally Posted by kevin
nice work on the tank mounts. mine are held on with my own toothpaste-tube style of welding . . .

i love the BSA watermelon motors. theyre so 1960s space-age looking, you know?

the Q16 didnt give me anything that C12 didnt already provide, except an eye-popping understanding of huge jet sizes. im really interested in plain gas, though so nitrous isnt in the cards soon, for me. im less interested in absolute speed than i am with going fastest within absurd self-imposed limitations.
Thanks Kevin, its slowing coming together but really pleased with the results so far. I'm switching fuels this season too, going with something a little more potent than the U4.4 in both bikes. Got a nice new set of Lectrons for the 750 bike and these 34mm Mikuni's will go on the 500. I understand where your coming from with interest of speed, I was similar with my A10. Wanted to see how fast I could get her in full street trim compared to stripping everything off and going for absolute speed.


1955 BSA Bantam D1 Plunger
1956 BSA A10RR Street and LSR Bike
1961 BSA C15S
1966 BSA Lightning
1966 BSA Spitfire - Soon to be an A50 Powered LSR Bike
1969 Triumph T100C
1970 Triumph TR6R
1970 Triumph TR6C
1972 BSA Lightning LSR Bike
1974 Triumph T150V
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Originally Posted by pushrod tom
Gonna be great to have another Beezer out there. Lookin' good!
Thanks Tom and yes, will be great for another Beezer to be out there running with those pesky Triumphs


1955 BSA Bantam D1 Plunger
1956 BSA A10RR Street and LSR Bike
1961 BSA C15S
1966 BSA Lightning
1966 BSA Spitfire - Soon to be an A50 Powered LSR Bike
1969 Triumph T100C
1970 Triumph TR6R
1970 Triumph TR6C
1972 BSA Lightning LSR Bike
1974 Triumph T150V
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The stroke isn't what is limiting the RPM, it is the lack of rigidity and support for the crankshaft.
My Jawa 500 has a strike of 87mm and makes maximum power at 10,000 RPM
My GM500 has a stroke of 78.5 and pulls strongly past 12,000 with a rev limiter set at 13,500
Both have sturdy pressed up cranks with caged needle roller bearings directly on the hardened (and replaceable) mainshafts. End float is controlled by thrust washers. Pistons have a single 1mm compression ring and an oil control ring.
My Villiers based Greeves has a 72mm stroke and a red line set at 11.500RPM


BSA B31 500 "Stargazer"
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Greeves 350
Greeves 360
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Chris,
Here is page 26 of the book I'm writing showing possible improvement in aero by adding a legal tailpiece on an M class bike. That Air-Tech one you have looks very similar. Bring it to Loring next as I'd like to have a look at it.

[Linked Image from i.postimg.cc]

Tom

And to Andy Higham, what makes the Jawa able to rev to 10,000 rpm? I spin my B50 with 90mm stroke to almost 8,000, but am afraid to go higher. The B50 motor has pressed up crank, needle bearings, three main bearings (ball plus roller on drive side, roller on timing side). I'm running Carillo rod plus JE Piston on PES crankpin, so I wonder if the Jawa just has lighter parts, narrower bottom end, or some other trick to survive those speeds?


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Tom,I would think the quality of the engine casings play a big factor...
My bias opinion ,A and M class bikes should be just naked frame, no aero devices


61 hot rod A10, 89 Honda 650NT .On a bike you can out run the demons
"I don't know what the world may need
But a V8 engine is a good start for me
Think I'll drive to find a place, to be surly"
“
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The B50 crankpin with its short tapers and nuts isn't the most rigid arrangement.
The Jawa crank pin is 35mm diameter x 75 long and pressed the full width of the flywheels
The crankcases are truly massive

Last edited by Andy Higham; 12/15/22 8:10 pm.

BSA B31 500 "Stargazer"
Greeves 200 "Blue Meanie"
Greeves 350
Greeves 360
GM500 sprint bike "Deofol"
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'35 & '36 OK Supreme
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Originally Posted by koncretekid
Chris,
Here is page 26 of the book I'm writing showing possible improvement in aero by adding a legal tailpiece on an M class bike. That Air-Tech one you have looks very similar. Bring it to Loring next as I'd like to have a look at it.

[Linked Image from i.postimg.cc]

Tom

And to Andy Higham, what makes the Jawa able to rev to 10,000 rpm? I spin my B50 with 90mm stroke to almost 8,000, but am afraid to go higher. The B50 motor has pressed up crank, needle bearings, three main bearings (ball plus roller on drive side, roller on timing side). I'm running Carillo rod plus JE Piston on PES crankpin, so I wonder if the Jawa just has lighter parts, narrower bottom end, or some other trick to survive those speeds?
Tom, will certainly bring it to Loring in July


1955 BSA Bantam D1 Plunger
1956 BSA A10RR Street and LSR Bike
1961 BSA C15S
1966 BSA Lightning
1966 BSA Spitfire - Soon to be an A50 Powered LSR Bike
1969 Triumph T100C
1970 Triumph TR6R
1970 Triumph TR6C
1972 BSA Lightning LSR Bike
1974 Triumph T150V
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tommy, you sa the fuel tank doesnt have to be i front of the ridfer at Loring and SCTA.

where is it so required? ECTA? bub?


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Originally Posted by Hillbilly bike
Tom,I would think the quality of the engine casings play a big factor...
My bias opinion ,A and M class bikes should be just naked frame, no aero devices

thats also what im interested in. the only things i am thinking of changing on mine are adding pizza pans to close in the rear wheel and adding a wraparound of polyethylene plastic in front of the rear wheel to enclose the front and keep dirt clods out of the area in front of the carbs. im also musing over a kamm tail seat, but i really want to go as fast as possible without it.

i have a full fairing to fit when i decide to go full aero, and when i do that ill add a front fender, tail section, and whatever else i can squeeze out of the rules.


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Kevin,

AMA - BMST rules

9. Gasoline Tank
a. Allowed is an aftermarket tank, if it is mounted in the original tank’s position and its fuel capacity holds a minimum of 1.32 gallons.

SCTA rules and Loring Timing Association - Modified Motorcycles

7.F

Gas tanks, if not original equipment to the production model, must have a minimum capacity of 5 liters or 1.32 gallons.

Note that BMST states "Allowed is an aftermarket tank, if it is mounted in the original tank's position." Both Loring and SCTA do not say the tank must be mounted in the original tank's position. In any case, your tube tanks are permitted at all events as long as it has the stated capacity.

The other major difference is that BMST does not allow any streamlining behind the rider nor in front in the M class as follows:

"c. The riders seat/tail section shall not extend past the most rearward edge of the rear tire and shall not be higher than 5 inches above the lowest section of the top of the seat cushion or seat base if no cushion is used, nor shall it be wider than the rider as viewed from the rear.
d. The rear wheel (excluding the tire) must remain visible at all times as viewed from the side.
e. If the seat/tail section does not meet the above standards, the Chief Technical Steward will determine its legality by observing the motorcycle and rider in a race position to determine if the seat/tail section is an aerodynamic aid."

SCTA and Loring allows that the tail section must only comply with the partial streamlining rules, with slight differences between the two.

Tom


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i almost got snagged on that 1.32-litre rule. i ordered tanks i specified to contain 1.5 liters from the aluminum guy. when they came it turned out that he had measured capacity by taking the outside dimensions of the tanks, and not taking the 1/8-inch thickness of the metal into account, so the size was marginal.

i took the burette i bought to cc my combustion chambers and measured the actual capacities, and it turns out that they are 100 cc to the good.

but it was close.


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Kevin,
Unfortunately, you didn't have the benefit of the book I'm working on. From page 30:

"Tube tanks are becoming popular but you still need to have a capacity of 1.32 gallons. So let's say you have some 4" diameter tubing that is 3-3/4" inside diameter. The volume of this size tubing works out to .574 gallons per foot which means that you will need a minimum of 2.3 feet to carry 1.32 gallons. You'll probably have to use 2 pieces about 14" each placed on either side of the frame top tube, connected by a crossover running between and beneath them and two separate vented lids (or a crossover vent tube at the top) in order to fill them. You could use two fuel valves in place of the crossover tube to feed your carburetor(s). I've never seen an inspector ask to check the actual capacity, but to be safe, you had better make them longer than above because you won't be able to actually add 1.32 gallons if you use that minimum length.

While we're on the subject of gas (or fuel) tanks, be sure you use a fire resistant sleeve or braided stainless steel fuel line for all un-valved portions of the fuel system (Loring, SCTA) including any crossover lines, and on all fuel lines for BMST. Also, you cannot use plastic filters or fuel lines unless they are specifically marked for fuel use (do not go by what the box says, as tech inspectors won't accept that.)"

Guess I need to finish that book.

Tom


Life's uncertain - go fast now!
Anything worth doing is worth doing well. Steve said that. Anything worth doing well is worth teaching to others. I said that.
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