MCRIDER007
Well-known member
We finally had a 50 degree sunny day and I took the opportunity to ride to Desert Valley Powersports in Prosser , WA and asked a tech in the service department if they had a copy of the 2014 ES Factory Service Manual (FSM). He graciously stopped what he was doing and took a few minutes with me to review the ES model's suspension spring rates. The first thing I noticed was that the fork springs were rated at a whopping 2.04 KGF/mm, double that of the 2013A forks....and the reason is that the ES only has one spring. The sole spring is in the left fork where it shares space with the compression damping adjustment. The rebound damping is in the right fork. The tech said this kind of fork setup is getting more and more common and I have heard about it in dirt bikes but not street bikes. He confirmed the single spring after looking at another section of the FSM although the parts list I looked up at home still shows dual fork springs.
The shock spring is listed at 685 lb/in which is actually less than the 708 lb spring used in the GEN2s Hard position and way less than the 976 lb spring Yamaha claims to be in the 2013A. Shock springs and their respective sag numbers, weight capacity, and resistance to bottoming can be a little to tricky to compare because of differences in base preload but the ES starts with a base preload of 14.5 mm and can be increased to a total of 22.5 mm of preload with the ES adjustment (per the Motorcyclist review). The 2013A's shock has 11.7mm of preload which is fixed. The GEN2's shock has 18.4mm of preload which is also fixed. I would guess that the ES (slightly lighter spring but slightly more total preload) spring would probably have very similar performance to the GEN2 when the shock is in the Hard position.
The ES's setup also is pretty close to how my Wilbers was orginally set up for my 2005. It had a 646 lb spring and 20mm of base preload (both verified by GP Suspension when it was rebuilt). I never rode 2-up but the shock clearly had bottomed numerous times and was very under sprung for my 225 lbs. The 646 spring was replaced by a 800 lb spring with 10mm of base preload. It is still under sprung for riding 2-up but works nicely on my 2008 for weights up to 250-275 lbs.
I think those planning on carrying over 325-350 lbs are probably going to need a much heavier shock spring and its anyone's guess how a heavier spring will work with the ES's preset damping combinations.
The shock spring is listed at 685 lb/in which is actually less than the 708 lb spring used in the GEN2s Hard position and way less than the 976 lb spring Yamaha claims to be in the 2013A. Shock springs and their respective sag numbers, weight capacity, and resistance to bottoming can be a little to tricky to compare because of differences in base preload but the ES starts with a base preload of 14.5 mm and can be increased to a total of 22.5 mm of preload with the ES adjustment (per the Motorcyclist review). The 2013A's shock has 11.7mm of preload which is fixed. The GEN2's shock has 18.4mm of preload which is also fixed. I would guess that the ES (slightly lighter spring but slightly more total preload) spring would probably have very similar performance to the GEN2 when the shock is in the Hard position.
The ES's setup also is pretty close to how my Wilbers was orginally set up for my 2005. It had a 646 lb spring and 20mm of base preload (both verified by GP Suspension when it was rebuilt). I never rode 2-up but the shock clearly had bottomed numerous times and was very under sprung for my 225 lbs. The 646 spring was replaced by a 800 lb spring with 10mm of base preload. It is still under sprung for riding 2-up but works nicely on my 2008 for weights up to 250-275 lbs.
I think those planning on carrying over 325-350 lbs are probably going to need a much heavier shock spring and its anyone's guess how a heavier spring will work with the ES's preset damping combinations.
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