Options for a German 31k - ?Restricted?

[geoffers997]

Hi All,
Alongside my poor running mystery which I think I'm making progress on thanks to forum member advice, I've been digging around on here and am wondering if I've got a restricted German bike on my hands. 

Here is what I know:

VIN is 31k-016364 which makes it a 1983 M.T.C 31W (what is MTC?)

Exhausts are stamped 31W-14711 and 31W-14721

Carbs are both stamped 31W-00

The German logbook seems to say its 37KW which equates to 50bhp.

I think I'm answering my own question here but everything seems to point towards a 50bhp bike rather than an unrestricted 59bhp bike.

This is what I'm now wondering:

Once the bike is up and running normally, just how hard is it to release the extra 9bhp and is it worth it; I'm thinking:

Carbs: Either replace with an unrestricted set (Mikuni VM26SS / 31K-00) or can I re-jet the existing 31W-00 ones to the sizes in the Haynes manual if the bodies are the same ?

Exhausts: Again, some choices - cut the existing pipes and remove the restrictors (shame to do this as they've lovely condition); buy a set of 29L unrestricted pipes; buy a set of nice expansion pipes and keep the existing pipes for my dotage.

First step is to get it running right, then I'll decide whether its worth derestricting it or just leaving it alone and riding the thing

Opinions welcomed 

[shaunthe2nd]

31w carb bodies same as 31k but with different jetting etc.
They can be re-jetted to match the 31k unrestricted type, which I believe to be as follows:

Emulsion tubes type 345-P.0
Standard needles type 5K1 fitted 4th clip down.

Main jets 240

Pilot jets 22.5

Air screw set 1.25 turns out

Floats set to 21mm

You need to check what the internals are in your carbs to see if previously de-restricted.

[geoffers997]

Thanks Shaun - this is exactly what threw me, all the jetting you mention is as per my bike (I will however check again to be better than sure). It wasn't until I started trawling the forum looking for other info that I found out about these 31W bikes and thought  'hang on a minute.....'

[midlifecrisisrd]

As said only jetting different in 31w carbs

As for the pipes it is simply a restrictor at the manifold end of the downpipe

Couple of tack welds to remove it

That is IF they are still there. Every set I've had were already derestriced

No other restriction

Steve

[geoffers997]

Thanks Steve, so there is nothing further down the pipe?

I saw some stuff on Xavier's technical reference site that seemed to imply there was a plate between the first and second cone after the header.

The headers themselves are the same bore as far as I can shine a light down them.

That plus what I believe to be jetting as per Shaun's post leads me to believe its already derestricted.

I'll sort the other issues out and then go wring its neck and see.

[midlifecrisisrd]

If nothing in the header and carbs had 240 main it is already derestriced

Its the 250 4l2 pipes that have the extra restriction in the exhaust

Steve

[geoffers997]

Brilliant advice, thanks!

There is a small part of me that is a tiny bit disappointed as I was going to buy a set of expansions if my current pipes were restricted; ah hell, maybe I'll just buy a set anyways who needs food? I'm fat enough to last a while without