100 Hour Big Bore Rebuild Questions

I have an 06 450 with 100 hours on it. I have decided to keep it and rebuild it to last at least another 100 hours. I am not the greatest mechanic but havea friend who is very proficient and will help me do the rebuild. I'm thinking about going with the Athena 480 kit. My questions are what else besides the kit (cam chain etc.) should I consider replacing. Also, I have also considered just going with a high compression piston and not doing the athena 480 mods. Just for the record, I want more low-end and would sacrifice a little top end to get it. Any advice??

The big bore will produce the biggest gains, but both approaches will beef up the low end. Using a heavier flywheel will also improve power in the extreme low ranges, and is very advisable in the case that you go with the big bore kit.

You might also read this:

http://www.thumpertalk.com/forum/showthread.php?t=720732

Thanks for the fast response and the additional link. I am also going to change out my chain and sprockets. I did have 13/50 gearing.Would the big bore athena do better with stock 06 13/49 gearing?

Possibly the vlaves and springs depending on clearance wear. If you do valves get steel valves for longevity (not that Yamaha is know for that issue) and possibly a set of HotCams stage 1 for more over all power.

Thanks for the fast response and the additional link. I am also going to change out my chain and sprockets. I did have 13/50 gearing.Would the big bore athena do better with stock 06 13/49 gearing?
The big bore will work better with stock or higher gearing.
The big bore will work better with stock or higher gearing.

Thanks, stock it is.

contact Travis D37 on this site. he owns Thumper Racing and is very experienced and knowledgeable at engine building. he built me a KTM (yes, I know, its not a YZF) 470 motor with some other mods and bike hauled the mail - controllably. I always got great starts with that bike and I made allot of ground when racing the uphill's at Glen Helen.

contact Travis D37 on this site. he owns Thumper Racing and is very experienced and knowledgeable at engine building. he built me a KTM (yes, I know, its not a YZF) 470 motor with some other mods and bike hauled the mail - controllably. I always got great starts with that bike and I made allot of ground when racing the uphill's at Glen Helen.

Thanks for the info.

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