Thanks Bob and Chris for the reply.
So the engine number is GYH512, im not sure if the H is specific to Douglas bikes. Bob, Im sure you will know more about this
I weigh 85kg and 6 foot, so a little larger than the ladies it was designed for. I may have to cut back on a few beers to increase the power to weight ratio. Once the bike is up and running i will start playing around with ratios, ill probably only get round to this early next year. It does have a 3 speed Albion box, but i have yet to try it, so hopefully all is in working order once i have the cracked casing fixed. I guess ill just have to play around and find out which ratio i prefer for my type of riding, it would be a great help it i could get that sprocket from you Bob, ill message you. While we on the topic of gears, Chris, you said you used 3 gear boxes to make 2 good ones. My casing has cracked where the clutch lever connects. i was thinking of getting a specialist to weld it, but if you have a spare from your 3rd unused box that would be even better. If you have it i would be happy to buy it off you. Ill post a pic below of that part.
Bob, would you be able to post a picture of your decompression valve clamping plate if its not a hassle? ill see if i can make a plan, and make something similar to ease the pressure that is on that point. otherwise i will make do with the botch job for the mean time.
Chris i would we very interested in seeing some pics of your bike, to help me with my build. When you got time could please post a couple. No rush. thanks for letting me know about that throttle, i will do a bit of research to see what i can find about them, but ill probably have a few question on this topic in the future.
I do need reverse handle bar levers. They seem to come in standard sizes of 1 inch and 7/8th, but the inside diameter on the handlebars in 18mm (im used to working in metric). So it seems like i am going to have to get someone to custom make a set to 18mm unless i can find a set that fits already. Chris do you know anything about these levers, and weather or not my only option is custom made levers.
Just got back from a shopping spree, bought new nuts and bolts so that i can replace most of the ones currently on the bike. There is currently a mix of metric and imperial on the bike so i am swapping to metric. I think it originally came with imperial. But i don't think anyone will consider that cheating, its just easier for me to work in metric. The current treads are also damaged, so it needed a fresh set of bolts.
Dave ill PM you the numbers. Thanks for the input
Thanks guy for all the help, when i started this thread i wasn't expecting to get to much feedback. It amazing what you can learn off forums when you new to a hobby.
cheers
Martin