Stability and buffeting

Hi.
As I said in my introduction I have been the owner of a low mileage 03 plate ST1300a. In general I'm quite pleased with it but have two major issues which are meaning that I'm not enjoying riding as much as I should, namely wind noise/buffeting and high speed stability. Tyres are almost new Michelin pilots and rear preload set at around two thirds. Under 80mph stability is fine but anything over that is usually accompanied by a gentle weave which although has never developed into anything too serious does mean I'm quite nervous about going any quicker. What makes it more unnerving is that sometimes (normally when your riding in clean air) it's absolutely fine but can start weaving suddenly for seemingly no reason. Several times this has occurred as I've been entering a curve. On all the bikes I've ridden over the years this has never happened (even the fireblade would only get a lttle flighty under hard acceleration) and does seem to be a quite serious flaw on something which I thought was supposed to be built for high speed touring.
I know I'm not the only person who has experienced this and am wondering if the cause has ever been narrowed down to anything specific? It currently has a Honda top box fitted so will try it without to see if it makes any difference . The other issue I have is the buffeting and wind noise. The bike came with a powerbronze after market screen which initially drove me nuts due to the fact it was quite noisy and also because that even with it on its lowest setting the top was directly in my eye line . Taking 2 inches off the top meant it was better but still not great. I next tried a bikequip flip screen which was marginally better but not as good as I was hoping. Today the powerbronze screen with another 3 inches taken off the top was refitted but the results were mixed. With the screen lowered right down it was unbearable and raised partially was about the same as the bikequip one. With it raised fully it was better but meant looking through it which I hate. It's been a while since I rode sports bikes but don't remember being bothered by noise or buffeting (maybe I'm just getting soft!) The plan now is to try a standard honda screen. Again I don't know if a solution has been found that works for most people but hopefully I'll find something that is ok for me.

My bike was fine until one winter layup during which I refilled the preload adjuster and 'fixed' the rear shock dampening. In the spring the bike did not like turbulent air (overtaking and passing semi's) whereas it had not been bothered before. After I restored the adjustments to the 'stock' position, the bike settled down.

I suggest you fill the preload adj. unless you do this regularly, and go by the book and put the shock dampening screw in the 'stock' position. Then go for a test ride.

Other guys have related deteriorating steering head bearings to this kind of behavior - but not at 'low mileage'. You might also loosen the left side axle clamp screws, bounce the bike on its suspension a few times, and tighten them to 23 ft lbs. Depending who changed the tires, they might not have followed Honda's procedure for replacing the wheel.

My 2010 has been fine up to 80mph on the interstates with the top box. (GIVI46) Twisties at that speed and cross winds in the straight I can feel the wing pushing on the box.
With the box off it feels solid at any speed. The last 2 years I pretty much only use the GIVI to keep the helmet in while parked at work.
I am considering a UNIGO or 3rd wheel trailer to put the extra's in while traveling along with a corbin smuggler.
I am not happy with the handling with the top box on at speed.

The top box can contribute to a high speed weave/wobble. Also, loose or "soft" suspension can contribute as well. Try it without the top box, as you stated, and see what (if any) difference you notice. Also, try adding some preload and/or damping to the rear shock to see what affect it has. Depending on your weight, you may want to consider putting heavier springs in the forks. I did and it helped the overall handling quite a bit, though I did not have a weave/wobble problem. The ST1300 is generally undersprung for "healthy" American riders like me (I'm 225lbs). Another thing to consider (which relates to your other problem of noise) is the screen position. Screen all the way up, top box in place, and soft suspension is the worst case scenario for developing a weave/wobble.

As for the noise, I too battled that for a while until I found what woks for me. I don't like looking through the screen so I found a different solution. I have a Rifle screen that comes with their "tuning blocks" that angle the screen so that the top is pointed back (horizontal) more than the OEM position. That helps to reduce some of the turbulence (which creates the roaring noise) created by the screen. To help even more, I cut a few inches off the Rifle screen so that, in the lowest position, the noisy turbulent area hits me in the chest rather than around the helmet (and my ears). The added benefit, here in Texas, is that I get more airflow to cool me off in the 100 degree summers. Others have built brackets to lower the OEM (or aftermarket) screen or change the angle. I tried that too but the Rifle setup is what works for me. The downside is that you have to lean into the wind a bit since it is now pushing on your body instead of being blocked by the screen. Try standing on the pegs at highway speeds and see the difference in noise for yourself before you start cutting things.

As always, YMMV. Do some searches for "windshield" and see what you find. There's quite a few threads on the topic.

Welcome to the forum and let us know what you find.

Thanks for the replies. I will wind up the preload and add some rebound on the damper and give it a try. I have looked into the screen issues, trouble is what seems to work for one person dosent necessarily work for another

Wolfheze said:

trouble is what seems to work for one person dosent necessarily work for another

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Truer words were never spoken. You have a modified bike. We all do. Mine is rock solid at all speeds that I care to do. That includes one nice stretch of rural interstate where I have cruised between 90 and 95 for up to 30 miles or so. Not bragging - I only ride this fast on this stretch and only a few times when I'm out that way. My bike does not like the turbulent air behind semi's - but it does not do what you describe and this is buffeting that can be expected (vortexes off jets can flip small single engine planes).

After you do the easy stuff - preload, etc. See if you can pick up a stock used windshield here cheaply and try that. Try taking off the top box. Your weave could be caused by tires, pressure, worn suspension parts, the list goes on, but it does not sound to me like it is caused by turbulent air or wind - that (in my experience) leads to random buffeting, not what I would describe as a 'gentle weave'.

Noise. I hate the noise caused by buffeting. I wear ear plugs and a Schuberth (supposedly noise rated). I also swapped my windshield for a taller and wider CalSci shield that is a little quieter. And, I have tried Bose's noise cancelling ear plugs. These are amazing, but have a limitation. (Search for Bose on this website - my review is about half way down,). Bottom line for me is that higher speeds mean more noise, turbulent air means more noise, and heavy, fast traffic means more noise due to the unsettled air and speed. I positively love riding in the early morning - quiet air and little traffic, and find that riding with a local club gets rid of the noise factor because we look for smaller roads - twisties - and its hard to go fast enough for noise to rear its ugly head.

Rugby UK ?

So your bike is OK to just beyond the legal speed limit

I don't know about the PowerBronze screen - the one I had on my ST1100 was very good, but I have had a couple of the BikeQuip flip-up screens, and they have been superb. Mine is the one that is a bit taller and a bit wider than the original. I believe that they brought out an even wider version. I have a series of photos comparing this to the original screen link here - so you can see if yours is the same model. If it is the same, then I can tell you that there is one point on the adjustment where the screen whistles and buffets, but that is easily tuned out with a slight adjustment to the screen height. Dead easy to do if you have the electrically adjusted screen. There were a number of variations with /without ABS and adjustable screens. I thought that the two went together, but on reading a couple of reports, it appears not. So do you have an electrically adjustable screen ?
If not, I can experiment with mine and let you know where the whistling and buffeting starts and stops.

The top box is a definite candidate for causing turbulence. Well - it the rider that creates the turbulence as the smoothed out air flows past the rider and then eddies behind his back. This then hits the top box from the side - each side alternately. Take the top box off, you still get the eddy, but there is nothing for it to hit. Put a pillion on the back, and the airflow is perfectly smooth until it passes the rear of the bike - with or without the top box.

There are a few other considerations. You have tyres fitted that are generally not OEM spec for the ST1300. I know that Bridgestone test the tyres that they recommend for the ST1300 exhaustively in different circumstances with the standard bike set-up. So you will know from their site that the tyres that Bridgestone recommend for the ST1300 are the F rated tyres for the BT020 and the GT rated tyres for T30 and T30 EVO. This is due to how the tyre is observed to behave in combination with the load and the suspension, and a whole load of other things. The F rated BT020 is an excellent base from which to work. The T30GT Evo is also very good and tested and approved by Bridgestone for the ST1300. I always find it odd that Bridgestone find it necessary to offer a different (GT or F rated) tyre for the ST1300, but other manufacturers do not. I think that there may be a big difference between having a tyre that is physically the correct size for a bike, and one which is tested (and indeed modified and improved) to work well with that bike.

How the tyre has worn can seriously affect the handling of the bike. I had BT023 GT tyres on for a while. They were superb, until the sides wore down, after which the bike wallowed quite badly in fast bends. I've not had that with either of the other tyres I have mentioned.

The amount of damping that is added in to the rear suspension can play a big part is how the bike feels. If it is too little, then the bike can pogo (boing boing) after going over a bump. Tyres with more flexible side walls will do the same thing and the combined effect can be quite unnerving if there is not enough damping.

The pre-load adjuster should be set so that when riding, the bike does not hit the top of the available movement in the damper, nor does it hit the bottom. It will need to be wound up if there is more load on the bike (such as a pillion, or extra luggage). In between the two extremes there is room for adjustment - but all that it does within this range in effect is to raise the height of the rear of the bike. It doesn't make the rear suspension any stiffer when riding.

Raising the rear of the bike has the effect of changing the angle of the front forks in relation to the ground - tucking the front wheel under the bike a little more. It is only a small amount, but it doesn't take much to change how the bike feels. It quickens the steering and can make the bike feel twitchy. It frightened the life out of me the first time I rode solo after a two-up camping trip fully loaded. I'd forgotten to reset it. It doesn't bother me know - my brain is used to the handling of the bike - but until I got used to it the bike felt very twitchy, especially at speed.

The final thing that comes to mind is what happened with the ST1300 between the earlier 2002 & 2003 models and the 2004 models. There were a number of complaints about the so called Pan-Weave. Some bikes had it and some didn't. Honda investigated and for the 2004 models onwards there were changes made to the way that the swing arm was mounted, and for 2002 and 2003 models there were new instructions for the re-assembly and tightening procedures for the engine mounting bolts and the swing arm bolts. I'm not suggesting that the changes were as a result the investigation, because I don't know. The timing seemed to coincide, that's all.

There were suggestions that expansion due to heat allowed the bolts be looser than they should be. That is just what I have read - it may be true or not. Certainly the procedures in the Honda shop manuals for tightening certain bolts were changed. Techniques such as tightening bolts to a higher torque, slackening them off and then tightening to a lower torque; tightening to a certain torque and then marking the bolts and tightening a further x degrees; changes to some torque settings - were some of the changes that I have spotted in the A4 addendum, from the original A2 / A3 shop manual . There's also a collar mentioned for the hanger bolts in the addendum, for which I cannot find a mention in the original. I've never had my hands on an A2 or A3 model to be able to fully relate the actual components to the diagrams. But there is a clear difference between the procedures for the two. It may be that your 03 model has been built according to the original installation instructions and has never been 'fettled' according to the later instructions.

You'll have to PM me if you want further information. And I have no idea as to how this relates to USA bikes, which I think started with a later model than here in the UK. Someone else may be able to chip in.

Hi. Yes I am near Rugby uk.
Thanks for the comprehensive reply, it took a while to digest all the information!
I had heard about engine mount bolts but there's no mention of this being done in the service book so maybe it's been done and maybe not. This is the first bike I've owned with a remote preload adjuster and didn't realise that resistance is supposed to increase as it's wound up. Tonight I took all of the preload off and tried to put some back on but the adjuster turns easily with the same amount of resistance until it won't turn anymore so it's probably safe to say the reservoir is empty. Not sure it's worth trying to refill it because presumably it will just empty itself again so I can either get a new one fitted to my existing shock absorber or go the whole hog and get a complete new unit. An Ohlins or Maxton shock is going to be I'm guessing between 6 and 900 pounds? so need to consider things carefully! . I've just bought a used standard Honda screen to see if it improves the airflow.

The refill of the fluid for the rear damper is apparently quite easy - although I have never done it. There are a couple of threads on it on this site - one of them here. - although I was reading a different one just the other night.

Its easier to wind up the suspension with the bike on the centre stand, but the 'standard' setting is 7 clicks from fully wound down. They do require more winding up as time goes by (at least in my experience), and the number of clicks before it gets harder to turn the knob increases with time - which seems to be due to the loss of fluid - but that doesn't happen overnight. I started wondering about doing mine after 70,000 miles and 6 years, but I traded in before I got round to doing it. Certainly worth considering doing a fluid change before splashing out on a new unit.

I like to look just over the top of the screen, but I find the stock screen blasts the wind, rain and flies straight into my face. The flip up lip takes it nicely over my helmet. I ride with my visor up a lot of the time and don't normally get helmet noise.

Read Larry's post #8 in John's link to the preload adjuster filling thread. These things lose the oil in two to three years. This is a standard maintenance item on these bikes. You don't skip oil changes because its too messy, skipping this because the oil will leak away in a few years similarly makes no sense.

Unless you ride every day just unwind the preloader when you put the bike away for the week or two between rides. Without constant pressure on it you'll never have to do the preload refill job but once, even in the 85,000 miles or so since I posted that thread.

Wolfheze said:

Hi.
As I said in my introduction I have been the owner of a low mileage 03 plate ST1300a. In general I'm quite pleased with it but have two major issues which are meaning that I'm not enjoying riding as much as I should, namely wind noise/buffeting and high speed stability. Tyres are almost new Michelin pilots and rear preload set at around two thirds. Under 80mph stability is fine but anything over that is usually accompanied by a gentle weave which although has never developed into anything too serious does mean I'm quite nervous about going any quicker. What makes it more unnerving is that sometimes (normally when your riding in clean air) it's absolutely fine but can start weaving suddenly for seemingly no reason. Several times this has occurred as I've been entering a curve. On all the bikes I've ridden over the years this has never happened (even the fireblade would only get a lttle flighty under hard acceleration) and does seem to be a quite serious flaw on something which I thought was supposed to be built for high speed touring.
I know I'm not the only person who has experienced this and am wondering if the cause has ever been narrowed down to anything specific? It currently has a Honda top box fitted so will try it without to see if it makes any difference . The other issue I have is the buffeting and wind noise. The bike came with a powerbronze after market screen which initially drove me nuts due to the fact it was quite noisy and also because that even with it on its lowest setting the top was directly in my eye line . Taking 2 inches off the top meant it was better but still not great. I next tried a bikequip flip screen which was marginally better but not as good as I was hoping. Today the powerbronze screen with another 3 inches taken off the top was refitted but the results were mixed. With the screen lowered right down it was unbearable and raised partially was about the same as the bikequip one. With it raised fully it was better but meant looking through it which I hate. It's been a while since I rode sports bikes but don't remember being bothered by noise or buffeting (maybe I'm just getting soft!) The plan now is to try a standard honda screen. Again I don't know if a solution has been found that works for most people but hopefully I'll find something that is ok for me.

Click to expand...

i have the same thing as you. Bike weaves at about 70-80. Hopefully you can get yours fixed!

If I get time at the weekend I'll have a look at the preload adjuster as it seems to be the most obvious reason for the instability. What type of fluid do you need to use?, don't want to destroy what might left of any seals.

Wolfheze said:

If I get time at the weekend I'll have a look at the preload adjuster as it seems to be the most obvious reason for the instability. What type of fluid do you need to use?, don't want to destroy what might left of any seals.

Click to expand...

It not so much bad seals, as it is a very bad surface finish on the cylinder. I polished mine up Last time I had it apart and it made a big difference. I put Honda fork oil back in mine.

Sent using Tapatalk

Wolfheze said:

What type of fluid do you need to use?

Click to expand...

Hydraulic jack oil is what I use.

Think I am getting the general picture on how to refill the preload adjuster reservoir but will still probably end up with oily hands and skinned knuckles when I attempt it at the weekend. One thing is still confusing me though and that's how to purge the air that will be in the line when it's reassembled. I understand the principle of winding in a lttle preload and then slackening the banjo to let the air out but there's no means of adding more fluid to take up the space left by the air as you can't refill the reservoir from the top. This means presumably that you will lose the effectiveness of the first few turns of the adjuster?

Wolfheze said:

I understand the principle of winding in a lttle preload and then slackening the banjo to let the air out but there's no means of adding more fluid to take up the space left by the air as you can't refill the reservoir from the top. This means presumably that you will lose the effectiveness of the first few turns of the adjuster?

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Yep, but not too worry, in two more years you will have the opportunity to re-fill it again.

They lose th eoil over time, you first lose a turn or two to air, then a little more, and a little more...

I think if I can get some preload on the spring and it cures the weave I will probably invest in a new shock without remote preload and set it up as a compromise between solo and pillion . Can't be doing with taking the bike apart every few months!

Wolfheze said:

I will probably invest in a new shock without remote preload and set it up as a compromise between solo and pillion.

Click to expand...

Better (and cheaper) to take the shock apart and put in a proper size spring. Save the pre-load for two-up.

Wolfheze said:

. Can't be doing with taking the bike apart every few months!

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It's not a matter of every few months - its more like once every year or two. I found many years ago, that when I stopped doing the easy routine maintenance items on my cars, I lost touch with them (so to speak) and was not catching incipient problems early in the game. For example, when I pull the preload to refill it, I look at the shock as well as I can, the hose, etc. When I pull a wheel for a new tire (as opposed to dropping the bike off at a repair shop) I check the calipers, the bearings, clean splines, slather on the moly goop, etc. While a good shop will do most of these items, will they do all the way YOU would do them?

From my pov, the hardest thing about refiling the preload adjuster is remembering to buy new crush washers (yeah, I know - just reuse the old 'uns).