Monstor 920cc sidecar Norton with 15:1 compression on Alky

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baz said:
I've often wondered about a Harley box on a commando
Are the Harley boxes good?
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Good is relative. Hard to beat the smooth shift of the AMC box.
They're certainly alot stronger.
Drag racers have been known to use them.
 
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MichaelB said:
Good is relative. Hard to beat the smooth shift of the AMC box.
They're certainly alot stronger.
Drag racers have been known to use them.
Click to expand...
Years ago when Harley's were rare over here I was talking to a bloke with a shovel chop
It had an A series BSA gearbox fitted he'd built the bike on a budget and couldn't afford a Harley gearbox to go with it ,I asked him how the gearbox coped with all that torque
He said it was fine with the beeza gearbox but he'd got through several AMC gearboxes before changing to BSA
I was surprised
 
Harley gearboxes are good. They can handle huge torque, they shift well albeit a slower shift than an out and out sports bike. They clunk like hell when putting them into first when stationary (unless you hold the clutch lever in for a few seconds first) and that awful clunk leads onlookers to conclude the gearbox must be shite! But they’re not.
 
Fast Eddie said:
Harley gearboxes are good. They can handle huge torque, they shift well albeit a slower shift than an out and out sports bike. They clunk like hell when putting them into first when stationary (unless you hold the clutch lever in for a few seconds first) and that awful clunk leads onlookers to conclude the gearbox must be shite! But they’re not.
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Yes, the clunk. Harley's signature. I hate it. (BMW boxer has it too.)
I read somewhere they either did or were going to engineer the clunk out, got overruled.
That's the way Harley's are and the riders expect it. Tradition you know.
 
For several years we held our Vincent Rally at a Motel/Campground at Crawford Bay, Kootenay Lake, BC. The road that the Campground is on is a very famous Motorcycling destination road. Sportbikers love and lots of Harley riders chug through there as well.
The campground is right at the point where a half mile straight ends with a sharp 90 bend.
Most of the Harley riders would downshift two or three times for the corner. I couldn't say how many downshifts the Sportbike riders made as they don't need to rev match. Also, you definitely cannot hear Sportbike gearbox internals from three hundred feet away where our cabin sat.
But the Harleys- CA LUNK!, CAAALUNK! on every bike, every time. It sounded awful.

Glen
 
The only 5 speed Harley box is probably the one in the Sportster motor, in which top gear is an over-drive. An XR750TT was a good attempt at building a Harley road racer, but the gearbox would always have been a limitation. The expense of building an XR750TT replica would probably be prohibitive, but the timing side bearing problem of the Sportster motor was fixed.
I was on Calder Raceway at the same time as Don Emde on the XR750TT - it was not slow, but that bearing failed.
 
acotrel said:
The only 5 speed Harley box is probably the one in the Sportster motor, in which top gear is an over-drive. An XR750TT was a good attempt at building a Harley road racer, but the gearbox would always have been a limitation. The expense of building an XR750TT replica would probably be prohibitive, but the timing side bearing problem of the Sportster motor was fixed.
I was on Calder Raceway at the same time as Don Emde on the XR750TT - it was not slow, but that bearing failed.
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Modern HD boxes are 6 speed.
 
Fast Eddie said:
Modern HD boxes are 6 speed.
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Are the Sportster motors still in production, and have a 6 speed box ?
Sportsters used to be the cheapest Harleys, and that motor was what the XR750TT was based on. A replica XR750TT with a 6 speed close box would be pretty good as a classic racer. About 30 years ago, there was a single make road race class in Australia for 883 Sportsters. It was dead boring and died very quickly. Most Harley stuff is usually too dear to play with, but Sportsters are not too bad. The frame of the XR750TT was pretty bad, but it could be made similar to that of an S1 Buell, and would probably still be accepted for classic racing.
When I was building my Seeley in the late 1970s, I considered both a Sportster motor, and a Jawa speedway motor. There was no class for the Jawa, and the Sportster gearbox was a problem
I was at the Broadford Bonanza a few years ago. There was a guy there who had built an XR750TT from bits he had bought off the web. It was pretty good It probably cost him a bomb - but there are sometimes ways of overcoming costs.
A complete late modern Sportster in Australia, can be purchased for well under $10,000. What does the upgraded gearbox cost ?
 
acotrel said:
Are the Sportster motors still in production, and have a 6 speed box ?
Sportsters used to be the cheapest Harleys, and that motor was what the XR750TT was based on. A replica XR750TT with a 6 speed close box would be pretty good as a classic racer. About 30 years ago, there was a single make road race class in Australia for 883 Sportsters. It was dead boring and died very quickly. Most Harley stuff is usually too dear to play with, but Sportsters are not too bad. The frame of the XR750TT was pretty bad, but it could be made similar to that of an S1 Buell, and would probably still be accepted for classic racing.
When I was building my Seeley in the late 1970s, I considered both a Sportster motor, and a Jawa speedway motor. There was no class for the Jawa, and the Sportster gearbox was a problem
I was at the Broadford Bonanza a few years ago. There was a guy there who had built an XR750TT from bits he had bought off the web. It was pretty good It probably cost him a bomb - but there are sometimes ways of overcoming costs.
A complete late modern Sportster in Australia, can be purchased for well under $10,000. What does the upgraded gearbox cost ?
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Yes, Sportster and the big twins have been 6 speed for a while, but I don’t know precisely when the changes kicked in.

Actually Al, HD must have been listening to you, as they have very torquey engines coupled up to quite close ratio 6 speed boxes. And although that sounds counter intuitive to many, it actually works very well indeed.
 
Fast Eddie said:
Yes, Sportster and the big twins have been 6 speed for a while, but I don’t know precisely when the changes kicked in.

Actually Al, HD must have been listening to you, as they have very torquey engines coupled up to quite close ratio 6 speed boxes. And although that sounds counter intuitive to many, it actually works very well indeed.
Click to expand...

Or they've lost the plot too ;)
 
Seeley920 said:
Or they've lost the plot too ;)
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I would never have believed an 850 motor would ever be quick enough to do what mine does. I am probably more receptive to signals from my race bike, than many other people. I once raced it with the standard Norton wide ratio gearbox - it was absolutely hopeless. But I might be more demanding.
With the heavy crank, we always need to find a way to use it's inertia to advantage. With wider ratios, you lose too many revs on each up-change - then you rely on throttle response, which with that motor is bad. If you wind the crasnk up and race change-up through close gears, the bike can be very fast. A Harley motor is very good, but the package is not really designed for combat. However that does not mean it cannot be made to really go. The XR750TT had potential, but the frame was hopeless and the engine was never raced enough to make it really fast.
I notice that current 1200cc Triumph models now all have 6 speed boxes, and so do the retro Kawasakis.

I bought my 6 speed TTI because I needed two more gears to get the bike off the start line in clutch start races. In most races we need to be well up behind the leaders in the first and second corners, otherwise the job becomes too difficult. Other than that the Manx gearbox is perfect everywhere., With the Manx gearbox, revving the tits off the motor to get the bike off the start quick enough is dangerous. However I am gratedful that these days we do not have to push-start our bikes in races. I used to be excellent at it - now it would kill me.
 
My TTI 6 speed gearbox cost $5000. That is about what a Quaife or a Shaflietner would have cost in the 1970s - not adjusted for inflation. I would never buy a 6 speed for my 500cc short stroke Triton - it really needed one. If I geared it high or low, I could choose where I wanted to lose a race. It had a 4 speed close box. I only ever geared it low once and found myself coming into a corner miles to hot behind the leaders - I went bush to miss them.
 
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