I have several old K&B 61s that I'm converting to Control Line.  MECOA sells a nice venturi and needle valve for the 61.  The problem is that the sides of the case opening for the venturi must be machined for the needle assembly to fit. 

I will get them machined if I must.  However, I don't like to machine anything unnecessarily.  I have tried my spare needle assembly for the ST 51 but it's to short also. 

What have others done that use the K&B 61?  Is there a readily available solution that does not require machining?

Thanks...Thomas

The hole for the venturi is the same on the old model K&B 61 and the K&B 4011.  The venturis I have had the same problem.  I took my little needle files and filed flats on both sides.  On one side I made the flat wide enough to get a socket driver in, on the the other side, narrower to hold the spraybar in place without it being able to turn. 

Just for the record, OS 40 and 45 FSR and 40 and 46 SF control line are a fit for KB 61 (at least for the model I own).
Regards.
Manuel.

Thanks all for the advice.  I'll try a few of the options you all have suggested.  If they don't work for my needs then I'll resort to the grinder.

Lee,

MECOA doesn't list the part number for their needle assy.  They do list a venturi..81-6151 81-6151 CONTROL LINE VENTURI K&B 61 GOOD  $8.60 .  I called MECOA (1.800.359.6972) and asked about the needle assy and they told me they have them and that the block would need grinding.  A friend bought a K&B 61 CL version for his Strega.  I saw the engine with the needle they sell and approximately 1/8" total is ground (1/16th each side).  The MECOA website lists the CL 61 engine but does not have a picture of it.  They do have a VECO 19 CL.  If you go to this page http://www.mecoa.com/kb/69/6951.htm  You can see the 19.  The needle assy on the 19 looks like the needle for the 61 but I'm sure a different size.

The K&B 61 that MECOA sells looks just like the the K&B 61 RC (6550) except with a CL needle.  Its on sale now for $103.  It is not the Screw head engine that they also sell. 

From all that Ive heard the K&B61 is a good engine and will power a Strega size plane.  Since I tend to bore holes in the sky and crash a lot, I prefer to damage a $103 engine than one of my more expensive engines.

Thanks again to all.  I guess I'll likely buy a grinding burr for my drill press and grind away.

Thomas

Just for the record, OS 40 and 45 FSR and 40 and 46 SF control line are a fit for KB 61 (at least for the model I own).
Regards.
Manuel.

HI Manuel

I guess you are aware  that the CL needle valve assm. for the  OS 40 45 FSR was  1.57 diameter  and teh ones for the 40 46 SF  are  .127 diameter, this will make  a  very huge  differance in the same size venturie, a .285 will act more like a 315 with the later  NVA

regards
Randy