I've got about 5 race weekends on a new 05 YZ125 so I figure it's time to change out the fork oil. I'm fairly inexperienced with the new twin chamber forks and was hoping to have a few questions answered:
1. The Yamaha manual specifies "S1" fork oil. I'm assuming this is a Yamaha designation. Anybody know what weight S1 is equivalent to, and does any brand/model of fork oil stand out as superior to others?
2. It appears that I'm going to have to basically completely disassemble the forks in order to drain both the damping assemblies and the fork tubes. Am I figuring correctly? I ask just because I want to know if I'm going to need all three tools: fork cap bolt ring wrench, fork cab bolt wrench, and fork seal driver.
3. I've seen mention of shimming-up the fork springs and compression damping adjuster (cartridge) springs due to a couple mm of free play (no preload). Is there a good reason to do this and, if so, what size and type of washers do I need?
4. The manual only specifies fork oil volumes, not levels. It looks like the damping assembly just gets filled then you let the excess flow out of an overflow hole while compressing the assembly fully. Am I correct me on this?
5. As far as the actual fork oil level proper does someone know what the stock height is? Can I even use a fork oil level gauge (like Motion Pro's) with the Kayaba twin chamber design? It looks like maybe the spring/chamber assembly (which I think has to be installed before filling) would be in the way if I tried to use the gauge, and I wouldn't know how much of i the assembly to have in the fork while measuring, which would affect measured oil level. Is going by fluid volume, instead of fork oil height, pretty much the only way to do this properly?
6. Anybody have a recommendation on how often to change the fork oil on this fork? The manual says "every 5 races" which isn't too helpful...don't know if they're talking race *days* (and how many motos a day) or actually every 5 motos. Not like I'm doing 30 minute motos, anyways. I race every weekend, 6 4-lap motos a day, and generally practice once or twice a week. Any suggestions?
I really appreciate any help you guys would offer up! Any other tips anybody could offer up to me in doing this maintenance for my first time would also be appreciated.
1. The Yamaha manual specifies "S1" fork oil. I'm assuming this is a Yamaha designation. Anybody know what weight S1 is equivalent to, and does any brand/model of fork oil stand out as superior to others?
2. It appears that I'm going to have to basically completely disassemble the forks in order to drain both the damping assemblies and the fork tubes. Am I figuring correctly? I ask just because I want to know if I'm going to need all three tools: fork cap bolt ring wrench, fork cab bolt wrench, and fork seal driver.
3. I've seen mention of shimming-up the fork springs and compression damping adjuster (cartridge) springs due to a couple mm of free play (no preload). Is there a good reason to do this and, if so, what size and type of washers do I need?
4. The manual only specifies fork oil volumes, not levels. It looks like the damping assembly just gets filled then you let the excess flow out of an overflow hole while compressing the assembly fully. Am I correct me on this?
5. As far as the actual fork oil level proper does someone know what the stock height is? Can I even use a fork oil level gauge (like Motion Pro's) with the Kayaba twin chamber design? It looks like maybe the spring/chamber assembly (which I think has to be installed before filling) would be in the way if I tried to use the gauge, and I wouldn't know how much of i the assembly to have in the fork while measuring, which would affect measured oil level. Is going by fluid volume, instead of fork oil height, pretty much the only way to do this properly?
6. Anybody have a recommendation on how often to change the fork oil on this fork? The manual says "every 5 races" which isn't too helpful...don't know if they're talking race *days* (and how many motos a day) or actually every 5 motos. Not like I'm doing 30 minute motos, anyways. I race every weekend, 6 4-lap motos a day, and generally practice once or twice a week. Any suggestions?
I really appreciate any help you guys would offer up! Any other tips anybody could offer up to me in doing this maintenance for my first time would also be appreciated.