Suspension - Bonneville America Forums

From Kansasbob... a method of measuring fork oil using a T square.

Quote:

First off the bike must be on a lift, the kind with the two forks and a foot pump. With the bike on the lift and the front wheel off the ground remove the bars and lay them on the tank that is covered by a blanket. Remove the fork tube caps, and pull out the spacers, washer, springs of both forks. Lower the bike carefully and compress the front forks all the way up. I took it really slow because I didn't know how it would react. It wasn't a problem. At this point you could measure the oil with the T-square (see picture)and see how much was in there, or just suck it out with your mighty vac and measure the oil you took out. I did both. I noted that all the oil I could get out without taking the forks apart was 325 cc +or- 5cc. The manual says dry they hold 484cc's There is some trapped in the bottom of the leg that I couldn't get out. I measured out 325 cc's of oil and poured it into each fork leg. I then took my T-square, set at 166mm per the manual, and slid it into the leg. The wide blade of the square lets you know where the center of the fork leg is so you can get the same measurement as you would get if you held the leg straight up and down off the bike. I added or subtracted oil until both legs were the same. I shot for 166mm or a little less because the progressive springs were supposed to displace a little more oil. In the weeks to come and after hitting a few big bumps I will know if I put in too much oil when the seals blow out.. If they do I will put in a little less next time ..... Questions?