This is sort of somewhere between a story and a tech topic.
Ever heard the saying never take anything for granted ?
Most of you will know I have not long finished restoring my 1950 Star Twin. When I finished it it started and ran very well, idled nicely and would cruise at around 55mph. All along I have been a bit dissapointed with its top end performance and pulling power, I wanted to get a few hundred k's on it before I made much of an assesment of it however.
Last weekend I went for a ride on a friends 48' A7 and it definitely had more go than my Star Twin which it shouldnt have. I knew mine was in excellent mechanical condition, has new carby's, reconditioned magneto etc etc. After much thinking I decided to check the valve timing, when I assembled the engine I lined up the appropriate marks, dot to dot on the crank gear and dash to dash on the cam gear. This time I put a degree disc on it and found everything was opening and closing 25 degrees too late. The marks on my gears are wrong ! They are one tooth out which equates to about 25 degrees.
I dont know if one of the gears has been replaced during its life or maybe it has been wrong since it was new.
The difference is amazing, it is a real little rocket now.
This bike was a runner when I bought it and I have spoken to two previous owners who both confirmed that 50 -55mph was about its cruising speed. Now it will easily run along at 65-70 mph.
So I guess the moral of the story is to check everything, I wont get caught like this again. I will check with a degree disc every motor I put together from now on. I have always used a degree disc on any engine there was any doubt about but the A7 is straight forward with its dots and dashes, or so I thought !
Brian.