I have a customer with a 2005 Yam WR250, not a tall rider. Wants to lower the bike, he weighs 190lb. One concern before we do it is the front forks, can only drop about 1/2” before hitting the bars, and will the stock spring work. he does want to start racing it. ( not a young man ). Please give me your recommendations.
That customer needs a heavier spring BEFORE a YamaLink to achieve proper sag. The 2005 WR250F is set up for a rider of about 160 pounds. As-is that 190 pound rider will have too much sag, the bike will understeer and will bottom violently no matter how much spring preload is used.
With a YamaLink that 190 pound rider will need a spring rate for a 220 pound rider due to the extra YamaLink leverage. Without a heavier spring the bike will behave even worse than the aforementioned due to leverage and excess sag.
With the forks there is NO 1:1 ratio. Meaning: lowering the rear 1.5 inches does not mean you raise the fork tubes UP 1.5 inches. After resetting sag and being properly sprung in the rear suspension we recommend a starting point of about 4mm to raise the forks. Even if the 2005 WR250 fork tubes could slide up 1.5 inches - which they cannot, not even close - the bike would oversteer and headshake violently. I'd say 90% of WR250 riders are settling around the 3mm - 6mm (6mm is 1/4 inch) adjustment range.