Idaho426 I have the yamaha service manual
for the 01 YZ426 that I will sell you. I just sold my 426 and I am selling the service manual. I am selling some things in the TT for sale section and I forgot all about the service manual until I read your post. To answer your question, I only had the service manual and I was able to figure out most most of my questions with it. If I couldnt figure it out from the manual then I could usually fill in the gaps by either posting a question here on TT or using the search function. I agree with EGO though, if you can afford it get both. Also, some guy posted mosted of the 01 service manual in bit-map
form awhile back. So you might be able to download that for free and just buy the clymer
manual. Then you would have both.