Tuesday, June 16, 2009

Fixed my Forkin' Problem

After suffering a mutiny of my ZR-7s' Handling Department last week, which included the Captain nearly being thrown into the drink twice on the same rainy commute, I decided to reign in my tired front boingers. Overboard went the water-thin old fluid (had been in over 29K miles) and OE springs, replaced by Progressive 11-1145 springs and fresh oil. I went with 10W oil (same as stock), using a Motion Pro fork oil syringe-tool thingie to set the level at 140mm (spring out, fully compressed) per Progressive's recommendation. The new springs are much longer, so to measure for the new spacers I simply laid the OE springs and spacer side-by-side with the new springs and supplied PVC pipe. I then added a very scientific "smidge" to make the new spacer an even 3". I reused the OE washers. I must've gotten the preload correct because the spacer stuck up about 3/8" beyond the extended fork tube, which is the "rule of thumb" preload check per Progressive. While the forks were on the bench, I took the opportunity to polish the upper tubes very well to remove dried beetle remains a/k/a fork seal killers. I also cleaned up the brake calipers and re-greased the slider pins. With everything back together, I did a half-arsed sag measurement using a zip-tie on the upper fork tube. It was at 30mm with no riding gear or luggage, so I must be in the neighborhood of the often-recommended 35mm. A test ride on very familiar roads revealed a much better behaved motorcycle; the front soaks up little bumps while holding up to sharp-edged bumps and also diving less under braking, which also gives me better feel for the rear tire while cornering, perhaps because the excessive fork dive/weight transfer is eliminated. Steering is much improved, too; it actually holds a line again. My ZR always handled well enough for me until recently, and now it's probably even better than new. Of course, having better feel out front will probably soon reveal how old the rear shock it getting, which means I better keep the credit card handy.

We don't need no stinkin' jack!
Old v. new. The red tool is a PVC cutter; very handy!
Workmate bench was handy as well.

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