OK, step number two then! First let me start off by saying that this blower is at least 15 years old and was found in the trash! I had to remove loads of grunge from around the engine just to find the mixture screws!!! I'm amazed that this thing still works even after all the abuse that I and the previous owners have put it through! Anyway I have laid the engine to rest for tonight as it really needed it. Tomorrow I shall get a gallon of premium and mix a new batch using my 10/10. As for the compression ratio God only knows on that one as this engine probably has about 1/2 an inch of coke in there after so many years of abuse! I know all too well about the detonation as I used to build and race 1970s two stroke race bikes. Those damn things, if they were slightly out on the mixtures would seize the centre cylinder and put your backside on the tarmac faster then you could blink! (Usually only when you were well over 100mph for maximum pain and discomfort!!!!!) I'll let you know tomorrow evening.

Thanks again for your help

Rich