eric_f Posted April 7, 2015 Report Share Posted April 7, 2015 Hi Eric, I'll give you my academic speculation here - The rebound on the rear is too fast and the compression looks slow.There might also be a preload issue. The rebound on the front is slow and compression is fast.Again, might be a preload issue. The wear pattern on the rear looks ok...good throttle habits.The very edge looks a little ragged to me.Perhaps you got on the gas a little hard when leaned over? You have not used the front tire fully, and the area that served as the " Edge " with respect to the amount you used looks ragged. If i am correct, the slow rebound meant the suspension collapsed early but did not recover in time, leading to punishment on the front tire. Was the bike understeering? I think you're right on the money. The bike does tend to understeer, especially if the throttle is only lightly rolled on. If I get greedy with the gas or apply the "hook turn" technique (depending on the type of corner) it feels like my line tightens significantly. Next time I'm in the curves, but definitely at my CSS class, I'll pull the screwdriver and notepad out while listening to what their mechanics say. I ran a zip tie on the fork leg and they are nowhere near bottoming, but too slow rebound is definitely a possibility. I think the rear is about as good as I'm going to get for stock. I may try 1/8 turn increments, but I am used to how it feels. I don't necessarily love it, but it's set where it will pack down the least. I have an Elka unit on order; no word on shipping yet. The front hasn't been adjusted since I installed the valving and bounced it for a few minutes trying to get it to "sit" at the top of the stroke at the same speed as the rear. Realistically, it's an F4i...I can't expect perfection...I have to keep telling myself that. Thanks for the insight! Quote Link to comment Share on other sites More sharing options...
Stroker Posted April 7, 2015 Author Report Share Posted April 7, 2015 Could you put up pics of the lovely F4? You could try the " Bouncing the bike " technique to see if the compression and rebound are off and get them to a good starting place.Mark a reference point on the forks noting the amount of travel available when the bike is held upright.Have a friend hold up the bike and push down on the seat.The suspension should - 1. Go down when you press down on the bike , but not collapse rapidly. If it does you need more compression damping. If it is too slow and difficult to push down you need less damping. Applicable for both front and rear. 2. When it returns , it should not go up past the reference point and down for another stroke or two. This means you need more rebound damping.If it slows down on the way to the reference point and does not cross it, you need less damping. Applicable for the forks. 3. When you have set the rebound, have your friend press down again.The front and rear of the bike should come back up as one. If rebound is off whack, then one side will rise faster than the other. 4. Make sure you set the preload before doing the above, and also ride around for a bit so the fork oil has gotten to temperature. I trust you know how to adjust the settings on your bike? Fine tune on track. How heavy are you in full kit? Quote Link to comment Share on other sites More sharing options...
eric_f Posted April 8, 2015 Report Share Posted April 8, 2015 Sure, this is the only picture I have handy on the PC. I'm sure some of you can identify where this was taken. OK, starting to drift off topic. I'm pushing 215 in gear. Thanks for the instructions, and yes, I am familiar with how my suspension adjustments work. I only have low-speed compression/rebound adjustment on the stock shock. Large suspension inputs bypass the adjuster amost entirely. I'm hoping to fix this with the aftermarket unit. Quote Link to comment Share on other sites More sharing options...
Stroker Posted April 8, 2015 Author Report Share Posted April 8, 2015 AAh....i have heard talk that these Jap bikes are usually tested by fairly light riders in the 120-140 pound range in full kit. The suspension is dialed in for this weight range. Add another 100 pounds and the spring is punching wayy above it's weight. Add to this the valving etc, and you need a full suspension tune before the stock suspension can handle your weight. Aftermarket is the way to go, and if you are holding on to this bike for a bit, invest money in good suspension front and rear. Quote Link to comment Share on other sites More sharing options...
csmith12 Posted April 23, 2015 Report Share Posted April 23, 2015 gosh... I am so late. Here are some fun and easy ones. I rode on these tires at JenningsGP doing some 1 on 1 coaching and a little bit of playing around in A group, for the new to me bike's first outting to the track. The rear should be an easy diag. Quote Link to comment Share on other sites More sharing options...
rchase Posted May 25, 2015 Report Share Posted May 25, 2015 I found a really helpful guide on tire wear through the BMW groups. Figured I would share. http://biketrackdayshub.com/motorcycle-tyre-wear-guide/ Learned a lesson about under inflating tires. Here's the tires on my nearly perfectly setup RR that were under inflated. This is one pretty slow session. Quote Link to comment Share on other sites More sharing options...
Stroker Posted June 6, 2015 Author Report Share Posted June 6, 2015 Hmm....looks like there wasnt enough weight on the front and the bike was understeering? That seems to have torn up the front tire a bit. Looks like you got on the gas hard as you were picking up the bike.The throttle control is good, as there is a clean area on either side of the worn area. Which bike was this? Were the tires warmed properly? Quote Link to comment Share on other sites More sharing options...
Stroker Posted June 6, 2015 Author Report Share Posted June 6, 2015 Robert, how did the under inflated tire feel like on track? Quote Link to comment Share on other sites More sharing options...
rchase Posted June 6, 2015 Report Share Posted June 6, 2015 Robert, how did the under inflated tire feel like on track? Not bad really. The bike had lots of grip that I was not really using all of. Felt well planted. When I say under inflated they were 26psi when I should have been running 28psi for because of ambient conditions. Quote Link to comment Share on other sites More sharing options...
Stroker Posted June 7, 2015 Author Report Share Posted June 7, 2015 A 2 psi deficit tore up the tire so? Quote Link to comment Share on other sites More sharing options...
ironkiwi Posted October 17, 2015 Report Share Posted October 17, 2015 This is a metzeler k2 racetek, with 29psi cold in it, hot temp after coming off track was 34psi Quote Link to comment Share on other sites More sharing options...
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