Timido Posted August 2, 2005 Share Posted August 2, 2005 Well after several days in the garage I got a lot of work done to my bike. I replaced front fork springs and fluid fluid level 155mm Front sag 35mm. New steering Head bearings Botom adjusting nut maybe 4-5 pounds Top Bolt 76ft Pounds. They stiff feel a little stiff. New Tires Pirelli Stradas. New DID chain and sprockets. I now know I should have only done one thing at a time. The bike feels a lot better soaks up bumps turns in a lot nicer no more decel wobble. Now my problem I seem to have some headshake at around 75-80 and up mostly felt behind the dirty wind of a semi. My only thoughts are the new fork springs raised the front slightly and might have messed up the geometry. My bike has a wing rack and a small set of Givis on it almost all the time. I have never had this problem before. Thanks all Tim Quote Link to comment Share on other sites More sharing options...
Redbird Posted August 2, 2005 Share Posted August 2, 2005 If it's specific to riding behind semis, it's not headshake, it's aerodynamics. This was explained to me by a much smarter person, but basically there's vortices formed behind a large truck that cause a back and forth motion to the air you're riding through. This will make it seem like your bike may be wobbling or unstable, it's not. My bike does it all the time- but only behind semis, where I don't stay for long anyway. If pulling out of the semi's wake solves it, you have no problem. Quote Link to comment Share on other sites More sharing options...
bartonmd Posted August 2, 2005 Share Posted August 2, 2005 My bike does the same thing... I don't know... Seems like it's mostly the wind hitting my shoulders and making them move the bars back and forth... Mike Quote Link to comment Share on other sites More sharing options...
N1K Posted August 2, 2005 Share Posted August 2, 2005 Now my problem I seem to have some headshake at around 75-80 and up mostly felt behind the dirty wind of a semi. EXACT same thing happened to me. AFTER the front springs were changed. I (ok, Tim and Dean) put new racetech springs in my front forks and changed the pre-load or sag or wtf it was. That raised the front end up quite a bit. We also shimmed the rear at the same time, but I think the front raised more then the rear raised. On the way home I felt like behind semis it was REALLY loose. I dropped the forks 6mm in the triple tree and it solved the problem. (well, technically I raised the forks 6mm in teh triple tree, lowering the front of the bike.) I highly recommend you give that a try. I'd be willing to bet it solves the problem. Quote Link to comment Share on other sites More sharing options...
azxx Posted August 2, 2005 Share Posted August 2, 2005 If it looks like this your springs are too long. Quote Link to comment Share on other sites More sharing options...
matey_peeps Posted August 2, 2005 Share Posted August 2, 2005 Why ride in the dirty air behind a semi? Pass the fucker! :twisted: Quote Link to comment Share on other sites More sharing options...
bartonmd Posted August 2, 2005 Share Posted August 2, 2005 ... come to think of it, I didn't notice it before I did the front springs/rear 6mm spacer... Mike Quote Link to comment Share on other sites More sharing options...
Timido Posted August 3, 2005 Author Share Posted August 3, 2005 I took the Givi's off and raised the forks in the trees about 6mm more and that helped some but its still there. I might try taking the stack of shims off the top of the rear shock and recheck my steering preload. I think alot of what I am feeling is there because the tires are actually round now instead of square. Quote Link to comment Share on other sites More sharing options...
Obby Posted August 3, 2005 Share Posted August 3, 2005 I took the Givi's off and raised the forks in the trees  about 6mm more and that helped some but its still there.  I might try taking the stack of shims off the top of the rear shock and recheck my steering preload.  I think alot of what I am feeling is there because the tires are actually round now instead of square. Had the same thing happen when I changed my tires recently. It steers quicker, but now I have a head shaking/wandering front end from time to time. Quote Link to comment Share on other sites More sharing options...
N1K Posted August 3, 2005 Share Posted August 3, 2005 I might try taking the stack of shims off the top of the rear shock and recheck my steering preload. I wouldn't do that... Lowering the back will in effect make the front higher again. Quote Link to comment Share on other sites More sharing options...
NHBandit69 Posted August 9, 2005 Share Posted August 9, 2005 I noticed the same thing after changing from the 190 that came on the bike when I bought it (used) to a brand new 180. Wobbles a bit behind semis, nice and stable all other times, and I LOVE the way she turns in now. I just pass the semi and drive on. Quote Link to comment Share on other sites More sharing options...
Fonzie Posted August 13, 2005 Share Posted August 13, 2005 Hey........Is that a picture of the long rumored '06 Blackbird American Chopper up there?!? Where's the Pauls & Mikey?? :wink: Quote Link to comment Share on other sites More sharing options...
pug Posted August 13, 2005 Share Posted August 13, 2005 I am not sure it matters but your oil level is too low. If i remember right, stock is 143mm and you can play levels between 135 to 145 mm. By the way, what springs did you install and what oil weight? Quote Link to comment Share on other sites More sharing options...
Timido Posted August 14, 2005 Author Share Posted August 14, 2005 traxxison 1.0 springs I weigh about 190lb without gear The fluid weight is racetech 2.5 Quote Link to comment Share on other sites More sharing options...
Skull Posted August 14, 2005 Share Posted August 14, 2005 It is definitely a ride-height mismatch problem. The exact thing happened to me when I put in a 1" lowering link but didn't do anything to the front. I slipped the fork tubs 1" and now it's rock-solid. Quote Link to comment Share on other sites More sharing options...
pug Posted August 15, 2005 Share Posted August 15, 2005 I think the oil you used is too light. Others in the forum use this weight but personally I use 7.5wt. If you cannot find 7.5, just mix the equivalent amount of 5wt and 10wt (preferrably from the same brand). What I have found from my early biking days is that firmer damping settings make the bike a bit more stable in side winds, sudden gusts e.t.c. Still I am not sure that this is your problem, it might be ride height related. By the way did you check tire pressure (42 psi), did you balance the new tires? Quote Link to comment Share on other sites More sharing options...
Timido Posted August 16, 2005 Author Share Posted August 16, 2005 I went and took the bike back apart and reset my steering head bearing preload because I knew it was a little tight. I check the fork oil level and added a litttle to make it about 140mm. I put everything back togther measuring everything torquing everything and I set the forks at about 49mm in the trees Stock was 39 and I am about 10mm less sag now than before so I figured the ride height would be close. I took it for a spin with the bags on the other day got on it a little and played on some local country roads. REAL nice so far now I just need to ride it on the highway. Quote Link to comment Share on other sites More sharing options...
Dano Posted August 16, 2005 Share Posted August 16, 2005 I'd be surprised if any bike doesn't feel the wake/wash of a semi. Two 40-ft trailers at 60mph move about 1/2 million cubic feet of air per second. If you have ever ridden a bicycle on the side of the road when a semi goes by then you know there is a hell of a lot turbulence. If you tires have the right pressure and your wheels aren't falling off, then you are OK. Drop back or pass-em. Quote Link to comment Share on other sites More sharing options...
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