Hello TR1 people,
 My written German is very poor so I won't even try.  However I can read German somewhat better.  Last year a collegue of mine gave me pieces to what was once an XV 920 race bike.  Many parts were missing and much information was lost over the years.  The bike featured a custom steel trellis frame with monoshock and early 90's GSXR wheels.  There was also a "TESI" style front end that was used in a 'frameless' version of the bike.  
 I can fabricate chassis pieces, exhausts,etc.  I would like some help with the motor.  The cases were bored and XV1000 barrells were used (overbored about 3mm to 3.875" with small block Chevy rings).  Are any other race pistons available.  The cams are Megacycle X-3 and the heads were ported and oversize stainless valves added.  The carbs are 38mm Mikuni TMs off a dirt bike I presume, as they are backwards for the bike.  This makes carb tuning a nightmare.  I also have very little frame to carb clearance and great difficulty in trying to add air filters.  I have thought about trying  to use downdraft carbs (such as 41mm flatslides, Honda VTR1000 carbs, or kitted SV 650 carbs).  Any thoughts this would be welcomed.  The motor also has a Gerex ignition that runs off one of the cams and a reed valve controlled vent on the other cam cover.  Any tips and tricks to making a powerful and durable motor?
 My other concern is finding parts.  Specifically countershaft sprockets and seals.  Is the seal available?  The bike has a 520 sprocket set, but the only front sprocket has 21 teeth  and my local track is short and tight.  I need some 520 front sprockets with fewer teeth.  Where can I get these made at a reasonable cost?
 Thank you for this website.  It gives me hope.
                                                                   Brian in Canada