I get arm pump pretty bad, but only on my throttle hand. I rode a 2016 YZ450 this weekend and the lighter pull throttle spring (2015-2016) helped a bunch. So with a little searching I found Tokyo Mods. They sell a lighter pull spring for 2010-2014 CRF450 & 250. This spring works on the 2014 YZ450F with some minor modifications.
This is the stock spring.
This is the Tokyo Mods spring as it comes.
These are the two modifications that need to be made. First straiten the hook (red line). Then unwind the spring 90 degrees (green line). Clip the excess wire to make it look like the stock spring. If your not getting enough preload, or the pull is too easy for you, you can unwind the spring up to 135 degrees to taylor it to your liking.
That's all you need to do. To install the spring you just need to take out the one allen bolt for the throttle body cover on the left side of the bike. Then one 11mm nut holds on the throttle cable wheel. Lightly tap the wheel to loosen it. Also, remove the cables from the throttle tube on the handle bar to get some extra slack.
You got a minute? Ever since I bought my 2016 I felt the Throttle "To me" didnt act
just quite right. Meaning.......it felt like it was making my right arm more tired. I am using a G2 Throttle Tube and rhe .25 cam which is G2's largest diameter cam which is the 1/4 turn cam.
I have the middle size cam on the G2 tube now which is the .50. After reading this thread,I dont know now if its me or the spring now.
Whats the comparison between the 2011 450 and 2016 450's throttle spring?
I liked the way my 2011 450's throttle felt. I need to do just a little something to my 16's throttle but just don't know qutie what.
It feels as if its not returning back fast enough for my liking so I adjusted the adjustment at the top out farther which I know this doesnt make it return faster but rather makes it have less play an more tedious but seemed to help some but I dont like the fine line of less play.
Do I need a stiffer spring down at the EFI throttle body or just need to adjust the the Throttle cable doen at cover? When I had that cover off it looked as if the bolts where up as high as they could go as far as the nut at the bottom goes. The nut at the bottom only had a thread or two of the bolt showing if I remembered correctly. I may go down in basement afterwhile and recheck it and take a pic of the adustment so you can see.