Manky Monkey Motors

Off work with a heavy cold today & bored.
Found this on Ebay. A shop in the States is selling the fuel tank, but I was kinda taken by the bike it's sitting on.

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Interesting.... But ugly.

Manky - you is odd!

only time iv seen the two engines togeather like that was on specials for french hill climbing. like icelandic 4x4 without the roll cage.

a few multi-engined bikes on this thread.............
http://www.mankymonkeymotors.co.uk/forum/index.php?topic=8535.0


re the double XS
Mmmmm, now that's got a lot of potential....... Guess it would need a transfer chain from engine #1 to #2 and then run the gearbox and clutch from #2  (as there's kick start shaft on #2)...... alternativly bypass both gearboxes and put a separate gearbox/clutch

Seen twin-engined Triumphs & Nortons but not an excess before.

Wouldn't mind running that down the ¼.  ;D

Nope looks daft to me..just go buy a bloody 1200 motor and stop F***ing about is what i say!...Voodoo...

And I thought you guys were open minded about unusual motors  :)
I've never quite figured out how twin engined machines work. Just how do you link two engines together? Is the final drive chain of the front one hooked up to the crank of the second? Or to the final drive cog of the second? Doesn't that put the second engine under twice as much strain as the first? Do you have a single coil/points setup, with two sets of HT leads? Presumably you'd take the gearbox out of the first & rely on the one in the second?

Twin engined Triumph sprinters, often supercharged! were popular in the 60's Mr. M.The motors were invariably pre-unit with the front motor coupled to rear via the primary drives,chain or Gilmer belt, and final drive off the single, often Norton or Albion gearbox. The engines ran independantly, but care in matching their carburation/injection systems, and ignition systems was essential....Morrag

http://www.thechopperunderground.com/forum/index.php?showtopic=50363 (http://www.thechopperunderground.com/forum/index.php?showtopic=50363)
thats its build thread

Can't see the photos without joining the forum, but certainly sounds like the guy knows what he's doing.

Morrag’s quite right.
It’s worth noting that when describing these things, terminology is important.

For instance. ‘Engine’ on a current jap bike (‘unit’ construction) tends to include the gearbox and clutch (so the engine and gearbox are a unit). There’s only one chain visible (the final drive chain) which goes from the gearbox sprocket to the drive wheel, which makes this chain gearbox-speed dependant.

‘Engine’ on a pre-unit bike (which is basically all the early British and the current big Harleys), is literally the lumpy bits that bolt onto the crank and make it go round & round.
There is then a chain/belt called the primary drive (this is running at engine speed) that connects the engine to the gearbox/clutch.
There is then a second chain/belt (final drive) which runs at gearbox speed to the drive wheel (same as for the unit/Japanese bikes above).

When folk wanted more power ‘back in the day’ it was a matter of tuning and cubes, however the biggest British bikes around 650/750/850 cc. So once the engine was tuned to the hilt (including superchargers), what was left……..  Answer – add another engine. (Busas, GSXRs Z’s were a few years off).

When the drag boys were coupling up these pre-unit engines in the 60s/70’s, they were using the largest engines that were available to them.
At the time the XS650 was first made (and for a year or so after too), it was Yamahas largest road going motorcycle. So the choice to go and get a bigger lump if you wanted Yamaha basically didn’t exist.

When the pre-unit lumps were connected together, a connecting chain went between the crankshaft sprockets of both engines.
Each engine had its own ignition (magneto way back then) and own carbs, which meant set-up was important to try and balance the power from the two engines so they worked together as opposed to against each other (debate still resides today about this).
This combined power was then fed from an extra sprocket on the crank of the rear engine, via a primary drive chain, to a gearbox bolted somewhere on the frame.
You now have to realise that this gearbox was taking the power from two engines so had to put up with a lot, so a strong gearbox and clutch was definitely order-of-the-day, hence the choices Morrag said.

Kick starts on the older bikes work by going through the gearbox/primary chain to the engine, so when you have two engines, kick starting becomes less-easy, so bikes were either push-started, or put on rollers to turn the engines over and fire ‘em into life.

It looks like this double-excess may have had the gearbox from the front engine removed, which implies its either going to use the rear-engine’s gearbox, or, it’ll have the rear gearbox removed as well and use a separate gearbox.
These motors can be made very strong, the grass track brigade take ‘em out to something like 1100/1200cc (??) on their outfits, so I’m guessing that the gearbox could be made to cope with 1300cc ?? As my mate dslam says, its got two choices!


Hope that helps Mr Manky sir.

its a great forum for xs650 stuff.
most of their tech stuff is xs650
engine mods and all sort of cool stuff
and ...............stuff
downside is they are yanks
hes got some sponsership for the bike now and is thinking maybe a preunit gearbox

Interesting, ver-r-ry interesting.

Not a bad description Tony, though I doubt that the Vincent or J.A.P brigade would have agreed with you on "available max. engine size"! check out George Brown's Super Nero, and Alfie Hagon's jumbo V twin sprinters, and with the state of tune of these beasts, kickstarting was never an option, believe me! Morrag

Good point, they probably wouldn't, oops  ;)

My brain was happily trundling along on the parrellel-twin more-affordable side of things.............  ::)

Been fortunate to see Hagon at close quarters (a pun and I nearly didn't realise it!) smoking the tyre for the best part of the quarter.
Also John Renwick on his fabulous Vincent (1665cc and 10.24/130mph with a sidecar and ballast). Often rides at the Brighton Speed Trials.
Found some nice shots from the 2009 Festival of 1000 bikes, one showing John's machine.

http://www.flickr.com/photos/tiger1john/3717582294/in/photostream/

(the pic before John's Vinnie are two Triumphs (single engined) with a couple of Mankies on board)


There's also the JAP that was ridden by the late great Basil Keys, his son brought that along to Brighton in 2010.
And I think I saw one of the Neros in action at the Blackbushe drags late 60's/early 70's.

Chap I know quite well has built up a JAP 'two of everthing' hagon-esque sprint bike only last year, last time I saw it it was running but in need of some fettling. (there's a photo of it in    in http://www.mankymonkeymotors.co.uk/forum/index.php?topic=8514.15 )

Old bikes being given what for...........................

Found this website, http://www.vintagechop.com/

some interesting bikes, including...........

and here's how to connect the chains in one easy-to-understand piccie

Love that XS sprinter. The motors look good canted forward -quite Nortonesque.

Found another excessive XS650.

First of 4 piccies

Piccie 2

piccie 3

...and piccie 4 of 4

aaahhhhh a rare pre unit yamaha

Great description matey, wish I'd thought of it  ;D

How about an XS650 cut away like that married up to a triumph slick shift gearbox or the burman "racing" gearbox. All tucked up in a cycle haven hardtail frame, 2n arf inches ground clearance, beach bars, stratched mustang tank................................................sorry people, just had a cold sweat then...........  ;D ;D ;D ;D

no foolin, got me droolin

yup me too  :o

Doesn't that front motor looked weird sliced in two. Hooked up to a Brit gearbox, or maybe something of more interesting/unusual origin it'd look fantastic.
Do it somebody -before I start looking again at my own XS project!
-anyone got a pre unit gearbox they don't want?!

"Slick shift" - coincidence time, added a bit to the thread (below link) and talked about chattin' to a bloke about having some ally welding, no prizes for guessing what for - a slickshift casing!  :D Funny old world................

Manky - two complete slickshifts sold last week on Ebay.

http://www.mankymonkeymotors.co.uk/forum/index.php?topic=8712.0

I've got a T120 gear box but ya can't have it!  ;D

thought T120`s were all unit construction............I could be wrong......... ;D ;D ;D ;D

__I could be wrong__

You are wrong.

no change there then !!!!!!!!!!! :D :D :D :D

lo, glad it isn't just me :)

The first T120 was built in 1959.






  I THINK.

and that was a damn good year that was  :D :D :D :D

22years before i was born

Now I feel really old.  :'(