Old multi-cylinder bikes of the 50s to later on. Japanese, British, Euro, etc

**Flettner** · 5th February 2014, 16:50

Originally Posted by husaberg

My head says big twin in a v for packaging, My balls say twin crank V4, but my heart says V3 about 450-550cc...
what ever it is it has to have parts available to suit at a good price..like 125mx or 54mm twin cranks or whatever......
i actually think a twin crank v4 might be cheap to replicate than a v3.......
although i guess if one were to use snowmoble and jet ski cranks etc i guess anything goes......

pics and many many more.....http://moto-works.bravejournal.com/

I was just thinking twin ( 700cc ) because I already have one, two if you count the parallel twin. I like 350cc cylinders as I have the mould to make them and seem to get acceptable results with this size cylinder. It would never be a world beater but it would be a lot of fun and I would imagine more power to weight than most people could handle. Parts for this size cylinder are cheap and available.
I would make the cranks anyway, suit what was needed with no compromise.

**husaberg** · 5th February 2014, 17:15

Originally Posted by Flettner

I was just thinking twin ( 700cc ) because I already have one, two if you count the parallel twin. I like 350cc cylinders as I have the mould to make them and seem to get acceptable results with this size cylinder. It would never be a world beater but it would be a lot of fun and I would imagine more power to weight than most people could handle. Parts for this size cylinder are cheap and available.
I would make the cranks anyway, suit what was needed with no compromise.

Stop doing stuff ya bugger. i think big is best but a 700cc stroke might be a nightmare to pipe. Then again its doesn't have to be optimal with 700cc i guess.

I think there would be a market for a Yamaha style 500 four neither of which my riding ability is going to challenge......

**Grumph** · 5th February 2014, 18:39

Originally Posted by WilDun

Just a thought, would a normal multiplate wet clutch (with all it's drag) be suitable in that situation?

It can be - but a dry diaphragm clutch is better. Run at engine speed or close to it, it doesn't have to be very big at all.

Apparently Cosworth were horrified at the size of clutch Norton wanted on the twin...Cosworth reckoned it was capable of handling about 300HP.....At crank speed which they were used to.

**husaberg** · 5th February 2014, 18:45

Originally Posted by WilDun

I'm told that there are clutches (from simple slipper clutches, to clutches similar to those used on many limited slip diffs) on the market which could make conditions better for the gearbox.
Setups similar to this (again I'm told) have been used to combat torsional vibration on light aircraft propellor reduction units (which also take a hiding).

Is it possible that this type of setup could make conditions a little more tolerable for the gearbox on such a bike?

Then again I could be getting into the realms of fantasy, - and again, maybe not!

Will.

Slipper or sprag clutchs are about overun, the motogp bikes now handle it more indirectly by not closing all the trotal bodies as you can do with FBW throttles and injection.
Funny enough Croxford said the cossy would lock on overrun, the NR500 (possibly on of the foirst bikes to have one)had one and was unridable without it.........

**Flettner** · 5th February 2014, 19:57

I have a Rekluse clutch in my YZ 250 twostroke ( mine is not the fuel injected one ) . I did not want to have it fitted, from an engineering point of view I hate the way it slips as it engages, quite a wide engagement range.
But after trying it out I'm shocked at how it changes the bikes power delivery. Before the Rekluse fitment it's typical 250 MX twostroke ( with aftermarket pipe, V force reeds ) snappy and liable to break traction without warning. With the Rekluse I can out traction a fourstroke MX bike out of most corners, with slippery corners I have the advantage. It won't be released from service, I like it.
I'm not sure how this would equate to a 700cc road bike but I'm sure if it helps the bike from breaking traction with out warning, it's got to be a step in the right direction.
This is why I'm so interested in the rotary valve engine, as I can control the throttle and timing via the computer. Computer will have various inputs that will help control ( dampen ) the riders irratic throttle commands. In my case sometimes not well thought out commands.

**WilDun** · 5th February 2014, 20:13

Originally Posted by husaberg

Slipper or sprag clutchs are about overun, the motogp bikes now handle it more indirectly by not closing all the trotal bodies as you can do with FBW throttles and injection.
Funny enough Croxford said the cossy would lock on overrun, the NR500 (possibly on of the foirst bikes to have one)had one and was unridable without it.........

My motorcycling stopped abruptly in 1983 after a crash, not because i was permanently injured but my wife banned me from riding bikes anymore! - so I have lost track of what has been going on since and I'm not up with the play re: sprag clutches and exactly how they work, but I've got a fair idea though.

However, I read up an article on aircraft reduction drives and their problems after having had a flight in a light aircraft - when it was sitting at idle waiting for take off, the engine and prop were fighting each other and the whole plane (literally) was being shaken so bad it worried me a lot!
It had a Rotax flat four, which should be smooth, but those props sure can create havoc at certain revs!

When a sprag clutch lets go, does it just release for a second or so and then re-engage itself?

Will.

**husaberg** · 5th February 2014, 20:21

Originally Posted by WilDun

My motorcycling stopped abruptly in 1983 after a crash, not because i was permanently injured but my wife banned me from riding bikes anymore! - so I have lost track of what has been going on since and I'm not up with the play re: sprag clutches and exactly how they work, but I've got a fair idea though.

the simple ones kind of look like a primary drive shock absorber on a old BSA ......
the rekluse are a centrifugal design clutch with balls they have a model that is auto yet still has a overriding lever clutch as well.
The Vincent had a cool servo clutch.
the diaphragm clutch also has a clever foible for lighter action.....

**WilDun** · 5th February 2014, 20:28

Originally Posted by Grumph

It can be - but a dry diaphragm clutch is better. Run at engine speed or close to it, it doesn't have to be very big at all.

Apparently Cosworth were horrified at the size of clutch Norton wanted on the twin...Cosworth reckoned it was capable of handling about 300HP.....At crank speed which they were used to.

Norton did have a big single plate dry clutch on the Commando didn't they (I seem to remember reading that when they first came out) ?. - Guess it had to be big to handle the geared down torque.

FLETTNER, - guess that is the type of device I was trying to explain, but I'm sadly lacking in knowledge on modern day developments.

Will.

**WilDun** · 5th February 2014, 20:30

Originally Posted by husaberg

the simple ones kind of look like a primary drive shock absorber on a old BSA ......
the rekluse are a centrifugal design clutch with balls they have a model that is auto yet still has a overriding lever clutch as well.
The Vincent had a cool servo clutch.
the diaphragm clutch also has a clever foible for lighter action.....

Sort of copied from the Honda C50 then!

But now I'm now beginning to fill in the gaps between 1983 and 2014, - thanks.

Will.

**Henk** · 5th February 2014, 20:38

Those rekluse type clutches were great for hole shots on MX tracks, not so good for clutch pop wheelies over logs in enduros. They have probably moved on from when I was playing in the dirt.

**husaberg** · 5th February 2014, 20:48

Originally Posted by WilDun

Sort of copied from the Honda C50 then!

A bit flashier than that just google it or i will in a moment.........

**WilDun** · 5th February 2014, 21:11

Originally Posted by husaberg

A bit flashier than that just google it or i will in a moment.........

Basic principle is simple by the looks, but seems to have become quite sophistocated in its construction.

HENK, - to me, popping wheelies in the streets isn't necessary at all, - very spectacular but very dangerous, - (read H1A Kawasaki) - they sure could have done with it!

Thanks,
Will.

**Henk** · 5th February 2014, 21:18

Originally Posted by WilDun

HENK, - to me, popping wheelies in the streets isn't necessary at all, - very spectacular but very dangerous, - (read H1A Kawasaki) - they sure could have done with it!

Thanks,
Will.

Will

I've only ever poped wheelies on my road bike and bucket by accident, but off road they become necessary to hop logs and jump ditches.

Buckets at Mt Wellington this weekend by the way. Will be a quiet non points weekend.

**WilDun** · 5th February 2014, 21:26

Originally Posted by Henk

Will

I've only ever poped wheelies on my road bike and bucket by accident, but off road they become necessary to hop logs and jump ditches.

Buckets at Mt Wellington this weekend by the way. Will be a quiet non points weekend.

True Henk, the only reason i didn't do wheelies on the road was because very few of my early bikes were capable and I only did it on the track after that!

Might try to pop over to Mt Wellington Sat or Sun, but I don't think it would be a wise idea to try riding, my heart says yes, but my body and my wife say NO!

(A couple of years ago I ended up in hospital for a week when my mobility scooter ran off the ramp as I was unloading it off my old jeep in Bunnings carpark!).

Will.