I changed the fork oil seals and decided to go for 20W fork oil in place of 15W (as i mentioned in another thread). The previous 15W was new-ish so the changes dont have to do with oil being old but viscosity only, i suppose. Highest (3rd settting) preload on the springs (20mm or so spring pre-compression). 30psi front tire. Went to test ride today, twisty local backroads, 100kmph zone. The fork oil took some time to warm up, 15mins or so. I find the forks to be noticeably stiffer and transfer the road conditions to the handlebars more accurately than before. Low speed damping now feels just fine for how i ride (but not that i have tried any modern suspension so couldnt really compare with that). When heavy braking the forks dont dive nearly as much as before and I find the breaking feels more realible. High speed damping was a bit compromised (too harsh) so i re-adjusted the spring preload to the softest setting and tested again on the very same roads and the change in preload did the trick and took the sharpness out of the high speed damping. In the end i settled for the spring preload mid position. Which is good cos now i actually have some adjustability in the forks for various road/riding conditions Unfortunately, there is some play in the forks (only with the legs fully extended) and this is noticeable in certain situations. I think heavier oil somehow pronaunced this problem. I'm a bit worried that some overzelous guy might pick this up at the WOF and give me grief... . Anyhow... My rear suspension (stock) always used to feel better than the front but now it's the other way round and i can see how the rear could be upgraded. I have rear springs preload at the higest setting so i guess it's the springs doing all the work and the shocks dont do much. I havent ridden that many different bikes so would be interested (maybe at Taumarunui?) if more experienced folks might be interested in test riding Bruno and let me know what they think. I'm looking forward to a longer ride to get a better idea of the results but am very happy for now. I hope the seals hold a bit longer than the last ones... it's quite a bit of work changing them!
Well done Psy. Sounds like you are onto it. 20W eh? You try it leaned over in corrugated corners?
yeah, that's one thing that remains to be seen... fast long corners. i've had a look at suzuki manual and they suggest 10W20 and the way i understand oils is that the second number means viscosity at the operating temperature (wrong??). but i'm sure that the fact that the forks are worn out, to the point where you can tell there's noticeable play in them when they're empty, plays a part as well. perhaps for as new forks 20W would be too heavy? i guess i'm discovering something that must have been "news" 30 yrs ago, lol. but i'm having fun...
Psy, I'll swap bikes with you at Taumaranui. The effects of extra wear in the shocks internals will be reduced by increasing the viscosity. That's what people do with auto engines that start burning oil excessively too. If you go too viscous, you'll notice it in corrugated surfaces, especially on tighter corners. Not a nice feeling. You're fortunate to have adjustable preload. Mine was done with spacers. The 1150 is adjustable though.
Diesildick. Could you gain adjustability by swapping out your fork caps for a set off a GK (with air valves) Have heard it can be done easy and that air can then be used with a smaller spacer to provide a range of accessible adjustment
Yeah, I believe that can be done. I have just settled on the present setting since it seems good for my style of riding. I'd like some feed back from Psy too.
that's a deal, DD! DD That's what people do with auto engines that start burning oil excessively too. i think i might be one of them people... i use 15/40 in my gs
DD and i swapped bikes at traumanui. having had time to reflect on the experience i'd say the following: if i can for a moment forget how much smoother and torquier his engine is and only compare the suspension i think i'm pretty happy with my setup. the usual upgrade over the stock (for the air forks at least) is to fit progressive springs and use 15w oil (and that's what DD has). i didnt find much noticeable difference with what i have (stock springs (within spec) and 20w oil so i'll probably leave it as it is. what do you think DD? still may want to play with the tyre pressure. the somewhat harsh high speed damping probably has to do with the old technology more than anything else. time to concentrate on the rear shocks. they really work only with a maximum preload, dont think that's good.
Yeah, a pretty accurate assessment Psy. Your front suspension was slightly softer than mine and dove a bit more under harder braking, but not a major difference between the 2 setups. I never tried heavy braking on yours from high speed, so can't comment on that. I was running 31 psi (cold) up front. If you're on maximum preload for the rear, you'll need to up grade soon. I'm still using middle position on mine. I gather that some PO has fitted replacement ones on mine. I was using the same settings on HD too.
Croc, getting back to the air over caps, I do have them but I'm not interested in having another set of air pressures to regularly monitor. Tyres are bad enough. It may become an issue as the forks wear.
Fair enough DD. If I was to consider air caps (which I did briefly), I would want to link them so there was only one fill point. Easier to fill and less likelihood of imbalance. I decided against it for much the same reason and concern over how damping wouldn't be improved. I wanna go racetech emulators and new springs one day. Though seeing Psy's experiment has some value, I might try that for a while. Want to do Baz as well but haven't thought that through yet. totally clueless on how the cartridge doo dahs work on his forks
The anti dive is less effective, the higher the setting # you set to. It's really a relief valve system. Fork preload adjustment is pretty obvious.
If there is play at full fork extension it will only really come into effect coming out of choppy corners on acceleration from a safety aspect I guess, still not the best psy. It's a lot of bike for the puny forks in good condition. I really think you guys expect a lot more from those GS bikes than their original design brief, they are a touring bike and good all rounder after all. They have about 70kgs over my Mk1 but same dia forks... it's a big ass ask. Ian, our psyguy does tend to push his bike in the twistys a bit
i run 20w oil in most of my bikes, maiinly because im a fat bastard, but generally the forks in 80s bikes were setup for 60kg Asian girls you could add a fork brace, that might hide a few sins
but generally the forks in 80s bikes were setup for 60kg Asian girls I didnt get one of them with mine, Might be in the post, Heres hoping she turns up on a saturday delivery
