Yesterday I completed the long-awaited test ride of Project 31, a 1986 VFR700 F2. The test went well; the engine is smooth, carburetion is spot-on and it handles great. But, as I sat at a stoplight with the clutch lever held in, I could feel that the clutch was creeping ever so slightly toward engaging. I knew I had a clutch hydraulic issue.
I rarely break my personal rule of inspecting every component, but I made an exception with Project 31's clutch hydraulics. While cleaning and inspecting the master and slave cylinders I could see that fresh overhaul kits had been installed sometime in the not-to-distant past, so I let them pass. My mistake, as disassembly of the clutch master revealed a ring of corrosion in the bore (pink arrow in this photo). The rubber seal can't hold an effective seal at this point in its travel, hence the leakback causing the creeping clutch engagement. I can't hone or otherwise repair this tiny aluminum bore, so a replacement master is required.
I had a feeling that I should open up the clutch slave for a closer inspection as well. Good thing I did. The assembly was clean and there was, in fact, fresh seals installed…but the main seal was installed backwards! Amazingly, it functioned that way, but come on…even the Factory Service Manual clearly pictures the correct orientation. I can't trust the used seal, so a fresh one was fitted.
Yet another reminder to always verify someone else's prior work.
I rarely break my personal rule of inspecting every component, but I made an exception with Project 31's clutch hydraulics. While cleaning and inspecting the master and slave cylinders I could see that fresh overhaul kits had been installed sometime in the not-to-distant past, so I let them pass. My mistake, as disassembly of the clutch master revealed a ring of corrosion in the bore (pink arrow in this photo). The rubber seal can't hold an effective seal at this point in its travel, hence the leakback causing the creeping clutch engagement. I can't hone or otherwise repair this tiny aluminum bore, so a replacement master is required.
I had a feeling that I should open up the clutch slave for a closer inspection as well. Good thing I did. The assembly was clean and there was, in fact, fresh seals installed…but the main seal was installed backwards! Amazingly, it functioned that way, but come on…even the Factory Service Manual clearly pictures the correct orientation. I can't trust the used seal, so a fresh one was fitted.
Yet another reminder to always verify someone else's prior work.
TIP: When servicing the clutch slave cylinder, here's a way to remove the piston without the mess of disturbing the hydraulic line. I unbolt the assembly and hold it over a small bucket while slowly pumping the clutch lever, forcing the piston (and fluid) out of its bore. The fluid empties into the bucket, avoiding the inevitable leakage onto the engine if the line is disconnected in situ. If you need the line removed for a more thorough service, an impact driver will easily remove its bolt.
In this case I was able to simply wipe clean the empty bore, refit the piston with its new seals, and bolt the assembly back onto the engine. Quick and clean.
In this case I was able to simply wipe clean the empty bore, refit the piston with its new seals, and bolt the assembly back onto the engine. Quick and clean.
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