What tach do I need for my '52 International?

acotrel said:
The unit that I've described looks right - isn't that the most important attribute ? .

So it looks good, but doesn't actually work ? How 'useful'. !!
May as well fit a steam pressure valve, or oxy-acetylene gauges ??
 
If it doesn't show anything under 3000 rpm, would you call that 'working' ??
Thats more than half the rev range of many older singlebangers.

Now, if you spun it with a 1:1 tacho drive, so it showed double what it was doing...

As was said earlier, any chrono speedo will also function as a tacho (needs to spin the right way, obviously), and have the face changed for tacho duties.
 
An Inter motor is the thirties single knocker manx. The only time you would look at the tacho is when it is doing over 6000 revs. If he is riding the bike around always doing less than 3000 revs, he won't even glance at the tacho, but if he ever fires up and gets stuck into it, he will then need it. The important thing is with something as beautiful as that, is to make it complete and authentic looking, as well as functional. Personally, I would love to own an Inter - it would make a really great Sunday bike, and you could really give the posers a thrill with it. The only reservation I have with the Suzuki RG250 tacho, is that it has the word 'Japan' printed on it's face. If the bike is parked somewhere, and someone has a really good look at it , they might pick the flaw in its perfection. I would never use parts which are obviously Japanese on a good British classic bike. They turn it into an instant shit heap. Would you use an electronic tacho on a Vincent Black Shadow, or Japanese chrome mudguards ? Some guys do that stuff, but I suggest they have lost the plot.
 
A strategic dab or 2 of paint, or acrylic superglue, on the face should render that made in japan unreadable ?

I've used tachos on other bikes to watch for clutch slip.
Since on old singlebangers this is more likely at lower rpm (you use the torque to pull you along in a high gear), this is where a tacho is most useful.

Cammy Nortons generally won't rev past their redline, unless you try really hard ??
Roadbike cammies never had tachos when they were new, obviously weren't a must....
 
Clutches don't generally suddenly fail completely, they go through a stage of minor slipping and heating up ? A tacho can detect this, if also have a speedo, and you watch closely for it.

Just seems to me that a tacho that doesn't show the lower half of the rpm scale is less than half useful on an old thumper. And can't even set the idle speed from it - although obviously doing it by ear is the traditional way with old bikes.
 
I've never used a tacho for anything other than to tell me when to change gear to stop the motor disintegrating. It is critical to know the limit of your motor, if you are fanging the bike. Most people use the cops as the rev limiter.
 
In case you haven't met one, an Inter will run out of power before it runs out of rev limit on the valve gear - unless they are geared really low. Never came standard new with a tacho, so obviously wasn't critical ?

If that suzook tacho showed zero to 3000 rpm range, would be great...

P.S. Recall reading an account of someone racing a manx outfit (sidecar)(early longstroke), the instructions were "rev it until you start seeing double, time to change gear...."
 
Rohan said:
In case you haven't met one, an Inter will run out of power before it runs out of rev limit on the valve gear - unless they are geared really low. Never came standard new with a tacho, so obviously wasn't critical ?

"

Surprising to hear that an International cannot be over-revved in the intermediate gears.
 
Rohan said:
Clutches don't generally suddenly fail completely, they go through a stage of minor slipping and heating up ? A tacho can detect this, if also have a speedo, and you watch closely for it.

So you can't sense a slipping clutch while riding, but you can if you have a rev counter that reads below 3000. Well, who's to say that's odd or anything!

. And can't even set the idle speed from it - although obviously doing it by ear is the traditional way with old bikes.

The clock is not usually very accurate at idle rpm.
 
I've obviously had a bad upbringing. As a kid we used to race one another on the public roads, and I always had hotted up Triumphs. I didn't have a tacho until I started circuit racing, so before that I broke a couple of cranks, However when I raced,I always used the short stroke 500 with a billet crank and it would cop 10,500 RPM. My Seeley commando is different. I always have big anxiety when it is revving at 7,000 RPM, so I watch the tacho like a hawk ! As fa r as your inter goes, the tacho is probably surplus to requirements until the day you decide to have a go at someone. You wouldn't want an Inter motor with a conrod poking out the bottom ? I would be surprised if it wouldn't pull 7,000 RPM in anger. If it won't do that, I'd be looking for a thirties racing camshaft, otherwise you could always buy yourself a Yamaha SR500 and keep the inter in your lounge room.
 
acotrel said:
If it won't do that, I'd be looking for a thirties racing camshaft, otherwise you could always buy yourself a Yamaha SR500 and keep the inter in your lounge room.

Late 40's and later Inters came with 'manx' magnesium camboxes and cams (plural).
Even though they are sohc, the cams are separate, and the overlap timing adjustable (within limits). Musta had a lot left over when the manx went to dohc ?

Be interesting to see the torque curve tested on a dyno.
 
Years ago when two str okes first arrived, I looked at a lot of old racing parts. There was a featherbed bike with a single knocker manx engine, and about three spare motors with bronze skulls cast into them. All of that stuff was really cheap compared with today's prices, and even back then. Those old manxes were not much slower than the double knockers, and as a street bike they would be really lovely. You would probably still get 45 bhp out of one - quite enough with which to do yourse lf a mischief. I would love to have an inter to play with, you could really give the Sunday posers a thrill with that ! There are still guys racing old single knockers in the UK - try the CRMC forum for a camshaft.

I took this photo at Goodwood Revival in 2008:

What tach do I need for my '52 International?


I think this one is owned by a friend of mine:

What tach do I need for my '52 International?
 
45 bhp out of an Inter ??
Factory quoted 32, for the road bike, and most postwar Inters CAME with sohc manx cams (note plural) anyway, and the magnesium manx cambox as well..

45bhp (almost 50% more) didn't happen until they went dohc, and gained a few revs along the way.. And had big fin heads, to lose some of that heat...
 
Some 350s turned out 40 bhp. I think a good 1959 model 7R was around that figure. I would have thought that a featherbed Inter would be fitted with milder cams than a 30s racer . I only had one friend who had a 56 model Inter. A couple had long stroke manxes on the road. One of my friends races a genuine short stroke 500, on the dyno it turns out 44 bhp. But there are slow and fast manxes. One of the fellas who had one of the long stroke motored road bikes, became a top A grader. His 500 and 350 were both ex Jack Ahearn - a famous rider in the 50s, they were both very fast bikes with a lot of works bits in them. His 500 manx is now owned by Wayne Rainey's father.
I forgot one thing - in Australia we run the manx nortons on methanol.

(Just had a conversation with an old Pommie friend who raced in the fifties. He says about 40bhp would be about the max for a single knocker manx.)
 
Anybody know anything about those chronometric clocks from India :?:
are they junk :?:
 
I hear figures mentioned for various singles, road and race, old and modern, that I find hard to believe. This season, I met someone who races a genuine Matchless G50 who was disappointed with the performance. He showed me the dyno chart, which had the typical power curve and a figure of 41 hp. He swore that everything was in tip-top nick and set up properly, so I have to assume it was a healthy engine. I was not too surprised at that low figure. There can be a huge difference between a racing single as it came from the factory race shop and one that has been tuned by a good tuner.

As for classic road singles, I feel that peak hp figures are not so meaningful because it feels cruel to rev the nuts off them. Even modern road singles feel stressed at the top of their rev range. I do think it's important to have a rev counter on bikes such as Inters because you would want to run them well down from absolute max revs so the engines will last. It would be a shame to damage a piston or a valve on such a rare and valuable machine. It's different if they are raced because they will be rebuilt regularly.
 
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