Throw the motor away and get a Norvel 061 and a texas timer backplate mount that you replace the Norvel backplate with. This is an easy conversion and is easily installed onto the Hyper viper without butchering the whole front up. It would be nicer if you had a pre revlite Norvel as the cylinder isn't so large around. Reduce the angle cut on the plastic tank to about 30 degrees or fit a sloghtly bigger on in. I use a bladder on mine. I know that that motor is going to run at top end till the fuel is gone.
The Norvel 061 is light years ahead in power without having to do diddly to it, compared to the slag Cox motor that they sell you