I had one when I was a kid but don't really remember much about it other than the fact that it was lime green, went like a bat outta &^%#, and that I had a lotta fun on it.
Might try the link below. Dan is a ricer guy, emailed me a schematic I couldn't locate one time, got back to me right away. Click on index and there is a section / tutorial on timing.
http://www.dansmc.com/
If that doesn't answer your question email him here and he will reply to your query.
http://www.dansmc.com/emailtome.htm
Hope this helps.