The Worlds Fastest NIMBUS

[Tman]

A possibility on the added mains. Could you make a girdle that goes between the pan and the upper case that also housed the two added main journals? The two stock mains would still be in the block.

[DND]

Hi Lars

After reading your reply's I see what you up against now, that little stock rod does look pretty good and could not see the I beam in the engine

Very good idea to have your frame welded by a pro till you get more seat time, as it is a one time deal once you start laying down that bead

Your friend sure has a squared away bike shop, very nice and the neat cut away engine too

Glad I tuned into your build thread and will seeing your neat stuff with each post

G Don

[ChrisLenahan]

Lars,  Just a though on the crank.  You might want to look at the cylinder spacing on some other 4 cylinder engines to see if you can find one that matches up.  It might be easier to swap in a different crank rather then modifying the original one.  A different crank would likely be staggered differently and would require the same for the cam. 

[wobblywalrus]

The modern Hinckley built Triumph was sorta like the Nimbus when I started to work on it for LSR in 2006.  There were very few people around who modified them and had a record of proven experience.  In fact, just one fellow did.  It was finding that person that was critical.  I could get his advice and build using his experience rather than go through all of the work he did to figure things out.  Perhaps those drag racers who rode Nimbi might have a solution worked out?     

[grumm441]

I had this turn up at work today
the guy was looking for some one who knew what it was and where to get parts
Well, one out of two isn't bad
G

[octane]

Grumm; an Australian Nimbus..now that's something !

The guy who runs that workshop I showed on the previous page can get you just about every
spare-part you'll need, and he's used to ship parts all over the world.

Click:
http://www.jcnimbus.dk/jc-engl.htm

...and if you have any problems at all with it, feel free to contact me and I'll be more that
happy to help you out.

Update and some rather brilliant news on the Nimbus build and replies to the comments above coming your way
very soon.

[grumm441]

Yep, who would've thought they would make it all the way to Aus
Apparently there are 14 of them here
Thanks for the Link
G

[salt27]

Yep, who would've thought they would make it all the way to Aus
Apparently there are 14 of them here
Thanks for the Link
G

Grumm, Steer clear of those 14 Nimbi, they were probably cast there for dastardly deeds or worse.

Oh, wait a minute, you were too, never mind. 

 Don

[octane]

.

Been a while.
I guess I fell asleep for a long time.
Just woke up:



..or maybe THAT was a dream, and I'm still asleep...
..or I'm dreaming I'm having a dream, where I woke up..

….NUUUUUUUUUUUUUUUUUUUUUUUUUUrse: give me my pink pills....NOW !

__________________________________________________________________



Again: thanks for all your advise concerning the crank-shaft,
but again: doing those rather sophisticated modifications just won't happen.
For several reasons, but most importantly; it's way way beyond my scope
and having someone make it is way way beyond my financial means.

Since I last posted I've had a few conversations with people generally
accepted to be the ones in-the-know when it comes to Nimbus engines.
...the guy who runs the Nimbus shop here in Copenhagen
...a Swedish guy ( more later ) who is known as probably one of a few
persons with the most comprehensive knowledge on things Nimbus-technical
...a guy from Vermont, USA (!) ( more later ) who is a brilliant engineer
and probably the other person with the most comprehensive knowledge on
 things Nimbus-technical.
They all say that I should stop worrying about it. The crank is immensely strong.
Check it, have it magna-flux tested for cracks... run it !

Perhaps those drag racers who rode Nimbi might have a solution worked out?     

Mmmmm: I'm afraid not.
No one has ever tuned a Nimbus to run it in anger on the drag-strip.
If you refer to the one running the strip on the video I posted,
then that one is just an ordinary Nimbus having a bit of fun.

They have been used for racing, but that was back in the forties/fifties
and not because they were suited for racing, but simply because these machines
were the only ones available.



…....but attempts to 'tune' them have been made:
...the Police used 'higher' pistons to ad compression, and speed up things
...apparently some crank-shafts with longer stroke were made.
Something I can't do btw. as it would bring me over the 750cc limit
...some made a cylinder-head/intake modification so as to
sport two carbs ( instead of one )



but the resulting power-gain is debatable. I did however get a message from one who runs it
and he reguraly takes his bike up to 140 km/h ( 87 mph ), which is not bad at all for the old
bumble-bee.

...then there's this one. Now that's quite exciting:





Unfortunately I can't find any information on it, but I'm working on it.
Would be interesting to hear about his experience.

One other 'racing' Nimbus is this one, about which I know nothing,
but a friend is working on getting in touch with the owner
( in Switzerland ).
Now turn up the volume on your PC, and listen to this.
It has a non-original carb, looks like a Mikuni flat-slide (?) and
it stumbles a bit first off, but listen as it leaves the second curve.

CLICK: http://youtu.be/g-I38mZmZNk?t=2m56s

That, to me, sounds pretty darn sweeeeeet !

[octane]

NIMBUSTIDBIT:

In 1939 a gentleman called Mr. Matsson took a small trip
through the United States on his Nimbus.
He rode it 18.319 km  ( 11.382 miles (!!!))

[octane]

Now here's another thing:
not only does it have just 2 ( crank ) main-bearings,
it also have just 2 cam-shaft bearings.
It's probably one of the very few 4-cylinder, in row, OHC engines
so (under- ) equipped in that department,
and I can't do a thing about it.

The cam-shaft lives inside this tube-shaped thingy:



...with a bronze-bushing ( is that what it's called in English(?)) at each end and
it is mounted by inserting it into the 'tube' from this end :



See? Nothing I can do about that. Not that I'm worried, even if I probably
will use 'stiffer' intake-valve springs, so as to 'hold back' the pressure
from the blower.


PS: don't ask about the avalanche of blue silicone. It's quite not-too-wise
and I never understood why people do it, and I never understood why they do not
understand that on the 'inside' of the engine there's an equal amount of useless
silicone-gum, that soon will float around in there and clog up things.
Those are just pics I picked off the net.

[Peter Jack]

I think this just looks like a real fun project!  

Pete

[Glen]

Lars, what Pete said, BTW I still wear the salt cracker tee shirt you sent me. Get lots of good comments on it.

[octane]

I think this just looks like a real fun project!  

Pete

Thanks Pete...it IS !

Lars, what Pete said, BTW I still wear the salt cracker tee shirt you sent me. Get lots of good comments on it.

I'm honored to know it's being worn by one of my heroes





...and a good looking fella' too !

.-)

[octane]

NIMBUSTIDBIT:

A guy posted this on FaceBook after seeing da' Nimbus:



Nice !

.