nhchris Posted February 17, 2019 Share Posted February 17, 2019 In a recent thread about suspension tuning the subject of moving the fork legs up and down in the triple trees was discussed. Is this really cool to do? I assume Yamaha chassis engineers designed the bike's geometry according to some optimum rules, ratios and measurements. Do you really want to mess with these in an effort to improve... what? Seems sketchy to me. What do others think? cb 1968 Triumph Bonneville 650 1971 Norton Commando Roadster 2002 Harley 1200 Sportster 2003 Honda ST 1300 2016 FJ 09 Link to comment Share on other sites More sharing options...
Supporting Member roadrash83 Posted February 17, 2019 Supporting Member Share Posted February 17, 2019 Moving the fork tube up in the triple tree is not unsafe to do, it is done all the time. Rember when doing suspension changes do one change at a time and see how it rides. He who dies with the most toys wins. Link to comment Share on other sites More sharing options...
norcal616 Posted February 17, 2019 Share Posted February 17, 2019 It's totally fine... At most forks get raised 10-15mm... this puts a little more weight up front and stability on high speeds... Best to adjust one thing at a time- you have to mess with settings to understand the black magic of suspension tuning... try going past/before the settings you think was "good" to get the suspension settings within the "goal post"... I prefer to test the suspension on a rough/choppy road vs a smooth parking lot... OEM test rider was a 130# teenager on a smooth glass road= not reality... RaceTech suspension book is a good source of information about suspensions black magic... 2012 wr250f - C-class 30+ age group 2015 fz-07- Hordpower Edition-80whp 2015 fj-09- Graves Exhaust w/Woolich tune by 2WDW @120whp Link to comment Share on other sites More sharing options...
BBB Posted February 17, 2019 Share Posted February 17, 2019 My forks are raised 10mm. I prefer the feeling of more weight forward. Red 2015 Tracer, UK spec (well, it was until I started messing with it...) Link to comment Share on other sites More sharing options...
Supporting Member betoney Posted February 17, 2019 Supporting Member Share Posted February 17, 2019 2 hours ago, nhchris said: In a recent thread about suspension tuning the subject of moving the fork legs up and down in the triple trees was discussed. Is this really cool to do? I assume Yamaha chassis engineers designed the bike's geometry according to some optimum rules, ratios and measurements. Do you really want to mess with these in an effort to improve... what? Seems sketchy to me. What do others think? cb Not "sketchy" at all, - adjusting the fork height in the clamps has been done for decades, street and dirt. I usually raise the forks about 5-8mm in the clamps to get more of a forward weight bias, it quickens up the steering and gives you a more planted feel of the front end. For sportier riding it makes a noticeable difference, for just puttering around town maybe not so much. Give it a try, you cant hurt anything and if you dont like it, its only a few minutes to change it back. Additionally, almost all aftermarket shocks are ride-height adjustable. ***2015 Candy Red FJ-09*** Link to comment Share on other sites More sharing options...
chitown Posted February 18, 2019 Share Posted February 18, 2019 Ditto to above. Not particular to this bike but as a general rule recommend making the changes in 5mm increments. More than one rider that decided "a lot more must be a lot better" has been caught out by the quicker steering and changes to stability. And, the occasional aftermarket horn or some other hard part making contact at full compression. Link to comment Share on other sites More sharing options...
nhchris Posted February 18, 2019 Author Share Posted February 18, 2019 So does stock rake and trail numbers change as part of the fork tweak? cb 1968 Triumph Bonneville 650 1971 Norton Commando Roadster 2002 Harley 1200 Sportster 2003 Honda ST 1300 2016 FJ 09 Link to comment Share on other sites More sharing options...
chitown Posted February 18, 2019 Share Posted February 18, 2019 Yes. And, wheelbase, etc. The manufacturer designs for what they think is the best compromise for the majority of the market. Sometimes that nails the sweetspot for me (Versys 650) sometimes it doesn't (nearly every other Japanese standard and sport bike owned). Many tens of thousands of miles on bikes with fork height changes with the only impact being they work more to my taste. Link to comment Share on other sites More sharing options...
koth442 Posted February 18, 2019 Share Posted February 18, 2019 Tuning frame geometry is a giant rabbit hole. I play with it on my trackbike(s). I haven't played with it on the FJ yet though. It's okay to play with. As mentioned above, it was designed as a compromise for the widest band of riders. You can tune it for how you ride. '15 FJ09 Link to comment Share on other sites More sharing options...
Tripletrouble Posted February 18, 2019 Share Posted February 18, 2019 Every time you hit potholes or bumps your suspension is changing height and will change the geometry. As BBB, raising legs in triple trees will put more weight on front which also sharpens the rake, making it slightly twitcher. Try it with a 10mm increment to feel the difference, over a variety of road surfaces. There's not one size fits all when it comes to set up, just experiment but keep a log of changes so you can go back to standard as a reference point. Link to comment Share on other sites More sharing options...
nhchris Posted February 19, 2019 Author Share Posted February 19, 2019 Just curious... Have any of you suspension tuners ever put scales under the front and rear wheels to measure the weight distribution of stock vs. raised front forks? I suppose a rider should be sitting on the bike for a test like this. It would be interesting to know what 10mm of rise equals in pounds of added front wheel load under static condx. My stock FJ turns in easily and is twitchy enough already (compared to most other bikes I've ridden). I think the longer GT swing arm is the route to better top end stability. But hey, I'm conservative when it comes to altering bike dynamics! cb 1968 Triumph Bonneville 650 1971 Norton Commando Roadster 2002 Harley 1200 Sportster 2003 Honda ST 1300 2016 FJ 09 Link to comment Share on other sites More sharing options...
chitown Posted February 19, 2019 Share Posted February 19, 2019 To offset stability issues (raised forks or not) might consider adding a link or two to the chain. Link to comment Share on other sites More sharing options...
Premium Member runnerhiker Posted February 19, 2019 Premium Member Share Posted February 19, 2019 I don't see any problems moving the fork legs up and down. I do see a lack of mentioning pluses and minuses. If you move them up you improve "this" but you make "that" worse. There is no doubt in my mind that you get both when moving the forks up. nhcris, I would suggest changing your question to add, if I were to raise the forks, what improves and what gets worse? I am sorry I can't add more details about the good vs bad, I don't have the experience and knowledge on this topic to expand. 2019 Tracer 900 GT Niwot CO USA Link to comment Share on other sites More sharing options...
koth442 Posted February 19, 2019 Share Posted February 19, 2019 If you want to know more, my friend and suspension guru Dave Moss is cruising around New Zealand on a Tracer 900 GT. He lives on the road as a suspension tuner and teacher, so unfortunately he charges for his content. But if you want to know more he's a great resource. Plus you can contact him directly and ask questions. 2018 Yamaha Tracer 900 GT, New Zealand – Dave Moss Tuning DAVEMOSSTUNING.COM Premium Article Excerpt. To read the full article please Subscribe or Login. Whenever we acquire a new motorcycle, the first choice should not be to take that ride to see what it will do. The first choice should be setting the bike up... '15 FJ09 Link to comment Share on other sites More sharing options...
nhchris Posted February 19, 2019 Author Share Posted February 19, 2019 Great info. Thanks guys. Just an FYI -- In stock kit, the 09s rake and trail is almost identical to the R1: 24 deg and 3.9 in versus 24*/4.0 in. The Tracer GT spec is identical to the FJ 09. The FJR spec is 26* and 4.3 in. I think trail is the spec that relates most to stability. cb 1968 Triumph Bonneville 650 1971 Norton Commando Roadster 2002 Harley 1200 Sportster 2003 Honda ST 1300 2016 FJ 09 Link to comment Share on other sites More sharing options...
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