Plus Specs

[ossalad]

Can anyone help me with the head and carburetor ( inlet throat bore and jet/needle) specs for the plus90 engines, my Mk3 sport has oversize porting and thinking they might be plus parts. Doug H. downunder

[eddie]

Hi Doug,
            The 90 Plus was supplied with various specifications dependant on the customer's intended use. The 'standard' machine equipped for road use had Amal 276 clip fitting carbs (RH 276EP/1B, LH 276EQ/1B) of 15/16" bore with a 6/3 slide, No.6 needle and a 130 main jet (for standard compression ratio). The list of extras for converting to a racer included TT type carburettors. With more tuning, some of the later models were running 150 main jets with silencers fitted, and 170 mains when running on an open pipe. Unfortunately, my information sheets don't give any dimensions for port or valve diameter.
      Hope some of this helps.
            Regards,
                        Eddie.

[ossalad]

Thanks for that Eddie, My heads are 26mm at the face of the port, so I have 626 Mk1 concentrics for it as original carbs are impossible to get and Mk1's are fairly common, I tried Mikuni's on the build 2 years ago and it would not even fire and now picking up a matching numbered machine (with S cams) have started the build again, the next Dougie is to be a Comp replica. Thanks again, Doug....downunder.