Dannytb Posted January 21, 2014 Share Posted January 21, 2014 Hello all! I'm having trouble with bottoming out on my '99 VFR800. I've installed new compression valves and revalved the rebound valves (parts sent from a professional suspension tuner). Springs are 0.95 kg/mm linear rate. Oil is equal mixture of Motul Factory 5w, Factory 2.5w, and Expert 5w to get as close as possible to the viscosity of Honda Pro 5w. I ride fairly hard in the twisties, getting to the edge of my rear tyre, and 5mm chicken strip on the front (Bridgestone S20 at both ends). I weigh 80kg, plus 10kg riding gear, and usually carry about 7kg of stuff in my gear pack. The oil level is set at 120mm. I had an incident where I was lightly trail braking toward the apex of a corner (at a lower speed than I normally take the corner because it was at night, and half an hour earlier I had nearly been hit by a suicidal kangaroo), then I hit a bump about 1.5" high, which caused a hard bottom out (loud bang and shock through the frame). The front tyre left the ground, and when it touched down it screached then let go. :( I've re-faced all valves and checked shim flatness, and they look ok on a flat plate of glass, but the bike still bottoms out when I do a quick-stop test (not emergency braking), and bounce testing overshoots at least once, sometimes twice, before settling. I've pulled one of the cartridges out again, and checked it for bush leakage, and there is some, but I don't know what amount of leakage is ok. The video I took is at this link: Is the amount of leakage from the top bush ok? This is a standard Showa cartridge (right-way-up fork) from the VFR, but with the valving changes. Any help that people can give is greatly appreciated! Link to comment Share on other sites More sharing options...
Member Contributer JETS Posted January 21, 2014 Member Contributer Share Posted January 21, 2014 Looks like leaky or incorrectly shimmed cartridge, or blown lower cartridge rod or upper free piston seals. Compression damping is not taking place. Go back through your assembly steps and look for some error. Link to comment Share on other sites More sharing options...
Dannytb Posted January 25, 2014 Author Share Posted January 25, 2014 Someone has come up with the answer on another forum: that amount of leakage is normal for these cartridges. It looks like I'll have to keep looking for other causes of the damping trouble I'm having. Thanks anyway for the ideas. Link to comment Share on other sites More sharing options...
Member Contributer Switchblade Posted January 25, 2014 Member Contributer Share Posted January 25, 2014 Are sure you dont have a tube that's bent or inter surface that is out of round .. Problem start after the collision with the jackass kangaroo right ? Link to comment Share on other sites More sharing options...
Dannytb Posted January 25, 2014 Author Share Posted January 25, 2014 Are sure you dont have a tube that's bent or inter surface that is out of round .. Problem start after the collision with the jackass kangaroo right ? I've checked the roundness and straightness and that's ok. The kangaroo was a near miss, but I had some bottoming out over bumps under brakes before that, so I can't blame the 'roo anyway. Link to comment Share on other sites More sharing options...
Member Contributer Switchblade Posted January 25, 2014 Member Contributer Share Posted January 25, 2014 Hmmmm. You mite try to email Jamie. Go here . http://www.vfrdiscussion.com/forum/index.php/user/6344-jamiedaugherty/ Link to comment Share on other sites More sharing options...
Dannytb Posted January 28, 2014 Author Share Posted January 28, 2014 Here's a photo of a typical interface between the shims/check plate and the valve that I've achieved: Unless Tapatalk changes the size of the photo, it should be 50x actual size at 100% on a computer screen. Also bear in mind that the gap looks bigger than actual because of the reflection on the check plate. Unfortunately, it doesn't seem that this has fixed the issue. I intend to test ride the bike in the morning, but the initial indications (tested rebuilt cartridges in a bucket of fork oil) look like the bike will dive just as much as it has been all along. Link to comment Share on other sites More sharing options...
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