I heard the 1989-91 powervalve system on cr250's is very hard to re-time and work on. I have to do a lower end rebuild on my 89 cr250 so I may as well do top end servicing as well. I was wondering if there are any things I should know about the hpp on the bike. I read erics book and it seems like its very complex and difficult to work on. I plan on buying a service manual so do you think that would be enough for a decent mechanic whos very mechanicaly inclined.
