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+--- Thread: High speed weave ktec springs and 10w oil (/showthread.php?tid=78261)
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High speed weave ktec springs and 10w oil - Covertlaugh - 07-06-17
Hi all,
I have recently had my fzs1000 forks upgraded with ktec springs for my weight and 10w oil as recommended by ktec. Generally the ride quality is improved. The bike also has r6 Shock conversion and 10mm forks through yolks. Tyres are Dunlop Roadsmart 3's. The bike has developed a high speed weave which can be experienced in the higher part of the Rev range at the silly end of the speedo but when short shifting behaves normally. The bars begin to weave side to side steadily increasing until I think a tank slapper is next. Worrying! Tyres are new, no apparent play in swing arm, head stock or wheel bearings, wheels balanced and in line, tyre pressures correct. I set the sag when I put the forks back in the bike. Now showing 2 and half rings preload. Compression not far off standard and rebound a little softer. I am 14 stone in kit. Any suggestions? Anyone experienced similar? I am assuming I don't quite have the suspension quite right as yet. Anyone similar weight with same fork springs and a set up? Thanks
Re: High speed weave ktec springs and 10w oil - celticbiker - 08-06-17
Are they linear springs or progressive?
What are the tyre pressures?
What is the rear ride height set at(relative to standard?
What is the weight distribution ratio.?
Re: High speed weave ktec springs and 10w oil - Covertlaugh - 08-06-17
Linear springs, rear ride height preload at third from highest, sag correct for my weight, tyre pressures front 35 and rear 39...and no problems at these pressures prior to forks being done. Can't say exact weight biase but with forks dropped 10mm and preload up at rear roughly front 52 and rear 48.
Re: High speed weave ktec springs and 10w oil - 5LV - 08-06-17
Firmer springs need more rebound
I went with 5w oil in mine and maxed out the rebound.
However it could be anything as you have new tyres, new suspension.
I'd lose a bit of air out of the front as well, down to 32psi to allow the tyre to work a little harder
Re: High speed weave ktec springs and 10w oil - celticbiker - 08-06-17
52 percent front is a bit higher than design so would suggest 36/42 Tyre pressures.
What spring rate is on the rear shock?
The standard on an 800 is 450kg but my custom nitron has a 700kg, if you have a standard r6 shock on I would suggest that the spring rate is way too soft now that you have the ktechs in the front.
Re: High speed weave ktec springs and 10w oil - Covertlaugh - 08-06-17
A few good ideas there guys. Once it stops pissing it down I will give it a try
Re: High speed weave ktec springs and 10w oil - Tmation - 08-06-17
Did you put the forks back in the yokes yourself?
I think your forks might be slightly out of line. (bit of a twist)
Try loosening the bottom yoke bolts a bit then bounce the front end up and down.
I assume the headstock bearings are in good order and aren't overtightened.
I thought 36/42 are the recommended tyre pressures.
Re: High speed weave ktec springs and 10w oil - celticbiker - 08-06-17
Yes that is the recommended pressures but you can run lower front if the weight balance is moved back.
With the balance he has running I think he'll need full pressure in the front and the rear is to soft anyway. I wouldn't be surprised if that is the main cause for the weaving but if the spring or high speed damping is too soft then that won't help either.
Re: High speed weave ktec springs and 10w oil - devilsyam - 08-06-17
see replies in r6 thread to same question and i also suggested tmations point
Re: High speed weave ktec springs and 10w oil - Covertlaugh - 08-06-17
Hi guys,
I intend to try the fork bolts tomorrow. Tyre pressure wise 42 rear is recommended for rider and passenger while 39 was for solo....it is in my Yamaha service manual anyway. The front pressure is my preference but again manual states 36. I was running these pressures before in metzlers and also Dunlop qualifiers with no issues although I fully accept the tyres are different now as is the suspension. Headstock and all other usual suspect bearings are fine. It's the standard r6 shock conversion in which case the rear Spring should be stiffer than the standard one. Dog ones were done as per Devilsyam's genius. I have one up on the high speed damping but no difference as yet. I will as I say try the bolts and all standard set up again tomorrow and see how we go. Thanks for the suggestions everyone.
Re: High speed weave ktec springs and 10w oil - robbo - 08-06-17
According to my book 39 is the correct amount up to 14 stone rider weight, and 42 for over that weight.
Re: High speed weave ktec springs and 10w oil - JKay - 08-06-17
(08-06-17, 03:18 PM)Tmation link Wrote: Did you put the forks back in the yokes yourself?
I think your forks might be slightly out of line. (bit of a twist)
Try loosening the bottom yoke bolts a bit then bounce the front end up and down.
I assume the headstock bearings are in good order and aren't overtightened.
I thought 36/42 are the recommended tyre pressures.
I think this would be my first check as I have had the same at lower speeds on my drz400 and it sorted it
I'd go 35/36 and 39 solo on the rear
Re: High speed weave ktec springs and 10w oil - tommyardin - 08-06-17
[size=1em]Just a thought do you have exactly the same amount/level of suspension oil in each leg.[/size]
[size=1em]?????? Just a thought.[/size]
[size=1em]I was also was told that when aligning the forks legs to loosen all bolts that connet the fork legs. [/size]
With the EXCEPTION of the top yoke/ leg pinch bolts.
[size=1em]I.e.: loosen front Mudgard bolts, pinch bolt on the axle (not the axle itself) and calliper bolts, bottom steering yoke bolts. [/size]
[size=1em]DO NOT UNDO THE TOP YOKE PINCH BOLTS.[/size]
[size=1em]Bounce the bike by pressing directly downwards/vertically on the centre of the top yoke and not on the handlebars, not in the direction of the fork angle but vertical and do not touch the front brake while doing it.[/size]
[size=1em]A helping hand from a mate or a willing wife is good to hold the bike vertical at the rear, 5 or 6 firm push down is enough and then without turning the bars at all, nip up all the opposite bolts a bit at a time crossing from one side of the bike to the other.[/size]
[size=1em]With saying all that about fork alignment it should not cause the bike to weave it just feels wrong cos the bars are not completely straight when traveling in a straight line, much the same as the steering wheel being out of line (steering wheel spokes) in the car.[/size]
[size=1em]Tyre tread pattern can cause the wheel to follow the treads. I recall the Dunlop TT 100 when they first came out in the 70's the were notorious for it, I had them on a 400 4F Honda they stayed on the bike for two weeks and I replaced the with Avons.[/size]
Re: High speed weave ktec springs and 10w oil - nick crisp - 09-06-17
I've never seen manufacturers tyre pressures as an absolute. As suggested by others, your weight and other factors may determine what is ideal for you. I've settled on 36 front, 40 rear on PR4s, think my weight is around 13st. But I find I don't need to adjust those pressures with touring luggage (I haven't gone particularly heavy, far less than a pillion would weigh anyway). Playing with pressures a pound or two either way might improve things. Others here clearly know more about suspension than me :lol
When I had standard forks on my last one, they were dropped through the yokes by about 10mm, and I found a tendency to a slight weave when maxed out. But since I'm a good boy and don't use the top end that much (:whistle
, I could live with it.
Re: High speed weave ktec springs and 10w oil - b1k3rdude - 09-06-17
(09-06-17, 08:34 AM)Hedgetrimmer link Wrote: I've never seen manufacturers tyre pressures as an absolute.I have ktec spring and the R6 shock and ages ago I found I had a very slow pouncture which meant the pressure at one point fell below 30psi. At that pressure the front got very light and wibbly
Re: High speed weave ktec springs and 10w oil - Covertlaugh - 09-06-17
So today I put the front forks back to recommended settings as per the fazer manual despite the ktec springs and thicker oil. I also put forks back to flush with yolks. I did as you suggested with the loosening of bolts, bouncing front and tightening. It made no difference. Hard acceleration around 110mph (closed road!) speed weave. Forks thru 10mm...standard settings...same. Forks thru 13mm! Same! Rear preload up to one off max. Same! Front rebound dialled back to absolute minimum and all as before...the bike is on its nose. Same though maybe not quite as violent. Really stumped! I am thinking of taking the forks back to the mechanic who fitted the springs and oil...summats up!
Re: High speed weave ktec springs and 10w oil - Covertlaugh - 09-06-17
I have gone through all the bearings again. I think the swing arm bearings have some side to side play. It wasn't noticeable before but after spending half the day trying to identify the problem with some high speed runs I am convinced it has play in it.
Re: High speed weave ktec springs and 10w oil - b1k3rdude - 09-06-17
What was the pressure in the rear tyre? the fazer 1000 only really likes 39psi or above in the rear.
Re: High speed weave ktec springs and 10w oil - Covertlaugh - 10-06-17
39psi
Re: High speed weave ktec springs and 10w oil - Ricky - 24-06-17
I to have a high speed weave since fitting Hyperpro progressive springs and the R6 shock, spoke to Luke and it is better but still trying to get sorted.Having front issues and hopefully Luke will be able to help, going to get a new set of tyres and see if it helps.