Author Topic: Do the Ton.  (Read 3421 times)

Offline Viking

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Do the Ton.
« on: 26.09. 2015 20:06 »
I have a 1958 A10SR with a RGS tunede engine, But I find it hard to "do the ton"
Hard to reach the Ton..

Engine rebuild in 1996. All re-done. SRM every thing. Incl. re boring of the to engine half.
Crank dyn. ball.

Engine tuned with: 1 3/16 monoblock ,
Cylinder head complet re-done by the cylinderhead shop with modern race valves.
Cylinder head: late type Big valve type.
Cam: spitfire scr. 357
Pistols, high comp.
New SRM cam followers
New rocker box parts....
Engine running a tad bit rich ( do not dare running to lean )
23T engine sprocket.
Std. Solo gearbox sprocket.
Running with octan 95...
Automatic advance unit
Magneto ignition
SAE 40 oil
19" wheel, with 3.25 front, 3.50 rear. Mitas tyres.
Silencers: SR twin.

Engine run like a "bat out of hell"
Power full and strong

But reaching the Ton, is a hard struggle.

What does it need to reach the Ton with ease ?

Offline edboy

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Re: Do the Ton.
« Reply #1 on: 26.09. 2015 21:27 »
hi viking, i would suggest either a little clutch slip at high revs or your main jet is slightly wrong. you need a rev counter for the clutch to check its doing its job and the factory settings for your carb main jet. if your magneto has different cylinder timing you can easily seize or hole the piston which will overheat. my tribsa was on song and going beautifully at high speed moments before i last holed a piston and its a real pain to strip it all down again. my first a10 habitually seized on the left cylinder as i always timed the right one, so check your mag timing on both cylinders or like some of us keep the speed down.

Online Triton Thrasher

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Re: Do the Ton.
« Reply #2 on: 26.09. 2015 21:44 »
How fast will it go in third gear?

Online duTch

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Re: Do the Ton.
« Reply #3 on: 26.09. 2015 23:45 »
 
Quote
How fast will it go in third gear?

 When I had my RR, was told a few times by older guys they went faster in third- wasn't game to try it out on mine tho'

 Top gear must be too tall for the power; I think there was a logical explanation here a while ago *conf*
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
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Online WozzA

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Re: Do the Ton.
« Reply #4 on: 27.09. 2015 00:04 »
Have you tried checking your speedo with a GPS..     *doh*
'51 Golden Flash Plunger
'57 Golden Flash Swingarm

Melbourne
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Offline bikerbob

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Re: Do the Ton.
« Reply #5 on: 27.09. 2015 08:38 »
I notice that you have a 23 tooth engine sprocket which is correct for 1962 RGS but in 1963 it reduced to a 22 tooth engine sprocket it could be that you are slightly over geared in top. If you have too high an engine sprocket it is possible to go faster in third than in top. Also are your other sprockets correct clutch  43 gearbox 19 rear 42 all these could have a bearing on top speed.

Online muskrat

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Re: Do the Ton.
« Reply #6 on: 27.09. 2015 09:11 »
I have even higher gearing 23-43-19-40 on my cafe. The motor is very tuned. On a flat road with no head wind I take her to 85 in 3rd so it only just drops off the cam (357) changing to 4th. It might take 1/2 mile to reach 120.
Cheers
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Offline RichardL

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Re: Do the Ton.
« Reply #7 on: 27.09. 2015 16:00 »

What does it need to reach the Ton with ease ?

I suggest finding a long straight piece of road where you can look out into the distance at a spot along that road that appears to be well below your position. Run your speed trial by pointing your bike in the direction of that spot while applying all available throttle.  *smile* ;) *whistle* >:D

Richard L.
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Offline Rocket Racer

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Re: Do the Ton.
« Reply #8 on: 27.09. 2015 22:58 »
I'd concur with over gearing as the likely culprit. But likewise for top end you should have the mainjet right
Do you run a tacho and if so what rev's are you pulling at whatever you are topping out at?


A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
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Online bsa-bill

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Re: Do the Ton.
« Reply #9 on: 28.09. 2015 09:09 »
on a standard but very good Flash - in my youth I think I did the ton, I think I did 94 in third, I think on both occasions my fleeting glance at the speedo needle would have been in nano seconds and it may well have been at the upper end of the needles oscillations, nevertheless if I could have afforded one I'd of bought a white silk scarf.
Seriously I was quite surprised at the speed in third, and frustrated at the length of road needed to achieve the same in top.
I thought the speed in third came at the cost of a bent pushrod, it may have been bent before that tho, always wondered why it bent and why only one
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online Ted_Flash

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Re: Do the Ton.
« Reply #10 on: 28.09. 2015 14:29 »
In 1951 The Motor Cycle got a one-way best speed of 102.75 mph at MIRA (104.5 with the air filter off).  And this was with 6.5:1 dished pistons and a 334 camshaft.

I presume it was achievable due to the combined effects of a) a brand new motor and b) it belongs to somebody else i.e. the factory.
Ted Wilkinson, Ramsbottom, Lancashire
1950 Golden Flash

Offline Viking

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Re: Do the Ton.
« Reply #11 on: 28.09. 2015 15:03 »
The engine is in super condition.

I changed the engine sprocket from 19T, using the bike to pull a Watsonian Monaco side car,
and changed it to solo with a 21T.
The engine was too low geared for high way cruising and uncomfortable at 50 mph.
It was like I could only use 1st and 4th gear.   2nd and 3rd was newer used.

This year I changed the engine sprocket from 21 to 23T
Nice. Much more compatible at 50 mph.
To gain more speed, I change down to 3rd at 50 mph. and keep it in 3rd until 70 mph +
The 357 cam like revs. and have a kind of flat spot between 45-60 mph.
I can keep it in 3rd, but as posted before, the gearbox have a tendency to jump out of 3rd if pushed hard.
Try to do 80-90mph in 3rd is not possible, for the time being.
The gearbox will be send to SRM this winter for a rebuild.

But the bike should be able to reach the Ton. Why is that important ?
If it can´t do the Ton, it ain't a Ton up Bike !

https://www.youtube.com/watch?v=CYvJVyXNZKc
https://www.youtube.com/watch?v=2vmzvlHrTCs

If it can´t do the Ton, you might just as well ride a Scooter…….= RIP.

Online morris

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Re: Do the Ton.
« Reply #12 on: 28.09. 2015 22:04 »
on a standard but very good Flash - in my youth I think I did the ton

I think one not insignificant fact overlooked in this discussion is the weight of the rider... *whistle*
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Offline Rocket Racer

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Re: Do the Ton.
« Reply #13 on: 28.09. 2015 22:25 »
Excepting the arguments about rider weight  ;) , this recent  *whistle* magazine article covers it nicely
A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
New Zealand

Online Triton Thrasher

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Re: Do the Ton.
« Reply #14 on: 28.09. 2015 22:26 »
Don't attempt high speed on some heap that jumps out of gear.

To do its maximum speed, a bike has to be geared so that peak power rpm occurs at maximum speed.

If it revs past peak rpm in top, it's undergeared.  If it won't reach peak rpm in top, it's overgeared.

If you don't know where peak power occurs, or have no rev counter, good luck.