First off, the title's the best way I could put it, English isn't my native language.
I'll explain - lately the bike's been feeling "wobbly" from the front end. If I let go of the handlebars, after 2-3 seconds it'll start to turn left. I've had my mechanic check it out - the wheel and steering bearings are fine (they were replaced like 2 years ago, since then it's been like 25-30 thousand KM, plus my mechanic checked them), the forks are OK, the tires are getting dry and will be replaced soon (they have like 23 thousand KM on them but they still have some thread left, it's within the "OK" limits). It really started out of the blue.
My mechanic suspects it's because I have a lot of load on the back (saddlebags and a top box), but I've been riding with that setup for as long as I've had the bike and I didn't feel any vibrations from the front end until recently. I thought maybe the tires got out of balance but my mechanic said they don't just "do that" all of a sudden. I did put a Katana shock on the back recently and kept the front forks stock, maybe that's why it feels wobbly? the difference in stiffness? it did happen around the time I blew my old shock (it sort of just "exploded" in the middle of a roadtrip and ran out of oil) but it didn't stop when I put on the Kat shock, which is in good condition.
Please, help!
If I were you, I'd remove the saddlebags and top box then go for a ride and see how it feels. If it has no effect, you can rule it out.
After ruling out the luggage, my main suspect would be the katana shock, which if I remember correctly, raises the rear of the bike. This would affect the fork angle, which might be causing that wobble.
Quote from: qcbaker on October 17, 2018, 12:50:54 PM
If I were you, I'd remove the saddlebags and top box then go for a ride and see how it feels. If it has no effect, you can rule it out.
After ruling out the luggage, my main suspect would be the katana shock, which if I remember correctly, raises the rear of the bike. This would affect the fork angle, which might be causing that wobble.
Yeah I'll try that, though I've had this bike for about 2 and a half years now and even when the top-box was ridiculously overloaded it was very stable on the front end. What you're saying about the Katana shock sounds very plausible, and I'm thinking of getting Sonic Springs for my front end soon to compliment the rear shock.
A Katana shock will indeed raise the rear end, with no rider on it about 1" and with a rider and gear, less. It's a much stiffer spring but the same length.
To match the Kat600 shock on mine, I put 0.90kg/mm fork springs which made a world of difference.
However I think your problem is likely tire wear.
Quote from: mr72 on October 17, 2018, 01:33:43 PM
A Katana shock will indeed raise the rear end, with no rider on it about 1" and with a rider and gear, less. It's a much stiffer spring but the same length.
To match the Kat600 shock on mine, I put 0.90kg/mm fork springs which made a world of difference.
However I think your problem is likely tire wear.
My front tire IS dry, as told by my mechanic, it's from late 2015/early 2016 by it's code, and I'll be replacing it within the next few weeks before the rain starts anyhow.
So...guess I'll change the tires and give it a try then. Tnx guys!
Quote from: mr72 on October 17, 2018, 01:33:43 PM
However I think your problem is likely tire wear.
Yep.. I think the same
Mine started suddenly wanting to tank slap after two years of being perfect. With a passenger on the back it's not a problem. My rear tyre is cactus and I strongly suspect that it is in fact the rear tyre causing the problem, I'll know for sure next month when I replace the tyres. Currently runny BT45's which were brilliant when new, but I'm going to try the Michelin, next go.
It just started happening one day, which led me to suspect bearing and the like but they all feel good.
Quote from: user11235813 on October 18, 2018, 11:32:12 PM
Mine started suddenly wanting to tank slap after two years of being perfect. With a passenger on the back it's not a problem. My rear tyre is cactus and I strongly suspect that it is in fact the rear tyre causing the problem, I'll know for sure next month when I replace the tyres. Currently runny BT45's which were brilliant when new, but I'm going to try the Michelin, next go.
It just started happening one day, which led me to suspect bearing and the like but they all feel good.
Every motorbike I've had so far has wanted to tank slap if I took my hands off the bars. Still haven't figured out what it is.
Have you checked wheel alignment? Something must be out of alignment / balance for the bike to not go straight. I don't believe that simply having more weight on the back and or raising the back end, would cause this.
Although both of these things might possibly intensify the problem.
Stop The Presses!
@Tundra
TL;DR, set the chain to be one and a half inches of slack on the centre stand.
Something happened today that had I not experienced it myself I would not have believed it. I've had some trouble with strange clanking sounds which I finally tracked down to the centre stand nut being loose. However once that was fixed there was some more subtle sounds. For about a year now I suddenly started getting the dreaded tank slapper if I took my hands off and gave the bars a tap. It did not happen with a passenger.
I think my chain is cactus and it goes loose fast now. Yesterday instead of having it slightly loose I put it much tighter than I normally would stilll within spect at about 22mm slack on the side stand.
Well fcuk me dead if not only did that eliminate the last of the sounds, but No More Tankslapping, even with a worn out tyre. I can take my hands off the bars now, give them a whack and instead of oscillating into a tank slapper, it just steadies itself instead. Just from keeping the chain at the tight end of the spec. Turns out to be 1 1/2 inches slack on the centre stand which translates to about 1" on the side stand. So try that and report back!
Re the chain I found a similar result after testing chain slack at maximum extension (using straps to pull swingarm up, etc - receive knowledge is that the change should have half an inch of free play at its tightest possible point). The end result for me on centre stand was just over 1.5 inches (40 mm) free play.
@herenow,
I guess that also explains why a passenger helps as it would tighten the chain a bit. However I must admit that do not understand the physics that would cause this. It's extremely bizarre and also explain other people who commented on my sudden tank slapping problems to say it was normal.
I'd be very interested if the OP would check back in after adjusting the rear chain as that would nail it for certain. Also I have removed the bar weights which actually make no difference whatever. Maybe Suzuki understand there's a potential tank slapping problem here and tried to head it off, unsuccessfully I might add.
Bar end weights are an attempt to change the resonant frequency of the handlebars and to reduce vibes through the grips.