Supertigre 2300 Carburetor "Drum Valve" BARRELS
See additional Supertigre carburetor information by P. Reivers at http://home.planet.nl/~preivers
Please contact him at preivers@wxs.nl for any questions regarding his information.
Photos and Hints about the "Rich Transitions" July, 2000
(this is a compilation of much VERIFIED information and experimentation of competent engine folks....contact me for names/emails if questions)
There are at least TWO versions of carburetor barrels. They are NOT identified by separate part numbers. Supertigre P/N 22313126, available from Tower Hobbies for $13.49....if you need one (it is listed as the Drum Valve for the 4500 - same part; Yes, it also has the "dogleg"...I've got them both; modified, it works fine.) The currently shipping carburetor has the 'dogleg' slot barrel, which we have found to be the 90% source of richening problems and poor transitions.
The photo below shows the two...the straighter groove is the best one, and was the original release version. In mid-1999, Supertigre modified the carburetor with two mods- a lower volume restricted lower venturi below the spraybar, and the "dogleg" barrel groove.
The dogleg barrel groove OVERLY richens the carburetor in the first 25% of barrel rotation. This is a disastrous and rapid richening of the motor, which causes terrible hesitation, bogs, and engine flame-outs on throttle up. This is particularly noticeable after sustained airborne low throttle maneuvering, and aggravated by negative g, near idle maneuvers.
The two fixes - ONE - enlarge the venturi bore so that the carburetor is the same ID on the TOP side of the spraybar as it is BELOW the spraybar. The magic number here is 29/64". A new, sharp drill, drill press, and that little guy is fixed.
The second fix is to modify the groove in the barrel. Careful cutting with a carbide cutoff wheel can make quick work of this. I have modified 4 separate carb barrels, 2 were "experimental" changes in angle, depth, etc. to find out the "trick"... The "Trick" ended up being the groove which was JUST LIKE THE ORIGINAL....
Top barrel HAD the wrong groove. Dremel the area shown in the black lines. The idea is to make it appear like the ORIGINAL barrel, shown on the bottom in the photo. (This photo courtesy of Dick Hanson from Bjorn Lenhardt, and is identical to other suggestions that have been verified to be true.)
Please don't hesitate to contact me at faipatrn@msn.com or emc2300@yahoo.com for additional information.
