Charles13
XS650 Addict
Personally I am not a fan of longer swingarms, but a much stronger one. Although I do have longer swingers on some of my bikes to get more front end feel I prefer the shorter wheelbase for wheelies and sideslides
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Geometry, rake, handling, high speed wobble & weave
- Thread starter Bjorn
- Start date
@Ratranger Do you happen to know the rake angle and the triple clamp offset? so wel can calculate trail and compare?
regarding weave and wobble, I would say mine is weaving at 100 km/h but its starts to get violent >140kmh.
@Charles13 thats very interesting! I have not changed the headstock area of the frame. I could though. To bad I had everything powdercoated back in the day, instead of painted, not great for modifications like welding.
Although my front fork is more modern, the swingarm and shocks are quite "period correct" age wise. Regarding the swingarm strength: It's one of my long term plans to build my own swingarm. So its on the list! I'm thinking about getting new shocks first. Also been on the list for a long time. Just got to decide wheter to get shocks in the original length or shorter. Especially if i plan on making my own swingarm (square tube is higher than a round tube.)
@dave_a Yes im gonna measure the weight distribution! Im just waiting on the scale to be delivered. Suspension sag including myself i did check, but ill remeasure and share it here.
regarding weave and wobble, I would say mine is weaving at 100 km/h but its starts to get violent >140kmh.
@Charles13 thats very interesting! I have not changed the headstock area of the frame. I could though. To bad I had everything powdercoated back in the day, instead of painted, not great for modifications like welding.
Although my front fork is more modern, the swingarm and shocks are quite "period correct" age wise. Regarding the swingarm strength: It's one of my long term plans to build my own swingarm. So its on the list! I'm thinking about getting new shocks first. Also been on the list for a long time. Just got to decide wheter to get shocks in the original length or shorter. Especially if i plan on making my own swingarm (square tube is higher than a round tube.)
@dave_a Yes im gonna measure the weight distribution! Im just waiting on the scale to be delivered. Suspension sag including myself i did check, but ill remeasure and share it here.
Wasn't suggesting S/W change, just that something is out of wack. Possibly weight distribution.
That said when things don't work, I always go back to the last thing I touched!
Bjorn - if your steering head bearing are too tight, it can cause a weave.
Forks should drop side to side under its own weight. No fore/aft movement, indicating too loose.
That said when things don't work, I always go back to the last thing I touched!
Bjorn - if your steering head bearing are too tight, it can cause a weave.
Forks should drop side to side under its own weight. No fore/aft movement, indicating too loose.
Like a tail wagging the dog.
This why I have 34mm forx with brace AND longer/stronger XS650sp2 with the short spoked 16" wheel.
The stock was tank slapping and anything but straight ahead.
Curves were weaving, corners were just awful.
Mind you, this is a Kaw 500.
This why I have 34mm forx with brace AND longer/stronger XS650sp2 with the short spoked 16" wheel.
The stock was tank slapping and anything but straight ahead.
Curves were weaving, corners were just awful.
Mind you, this is a Kaw 500.
It's about 25.4* of rake, 51mm offset from the zx6 lower triple, so it works out to somewhere around 3.4" trail.
@dave_a yes I like your suggestion! To be honest I don't know when this problem actually started.... Might sound weird, I know. But I've been changing stuff non stop for some 10 years. And I don't ride the bike a lot on the highway. Having sold a bunch of the stock parts, it's hard to go back. Did learn that selling stock parts is not always the best idea haha.
Here is what I'll do: I'll make a video showing the turning of the handlebars. The best I can do.
@AUTOMAN that's a lot of data on one print. Where did you use this for? Building a kawa?
@Ratranger that's a low number regarding the trail! Is your frame reinforced or anything? Any idea on weight distribution?
Here is what I'll do: I'll make a video showing the turning of the handlebars. The best I can do.
@AUTOMAN that's a lot of data on one print. Where did you use this for? Building a kawa?
@Ratranger that's a low number regarding the trail! Is your frame reinforced or anything? Any idea on weight distribution?
Since I like bikes so much, I like engineering, and I have a problem with my XS. Figured that's plenty of reason to buy this book:
I got "some" reading to do
I got "some" reading to do
demo of the steering head bearings. Please note that there are some wires/hoses and cables connected to the handlebars. It might not fall all the way to the end. But still feels pretty smooth if you ask me.
And I cannot feel play of I grap the lower end of the forks and try to move them.
The drawing is the final product of what worked for me.
Just for reference as to what to measure.
c
Like adjusting valves, head bearings change when tightening the top nut. Its a trial and error process.
In the video it looks a little tight to me. But what do I know? Its really a "feel" thing.
I'd loosen the top triple tree at the forks & top nut. Then loosen the stem lock nut, loosen the bottom nut until you get some fore/aft play in the balls. Tighten just enough to eliminate F/A play. Then tighten the top lock nut without letting the bottom nut move. (tricky w/o spec. wrenches) Assess where the F/A play is.
Trial and error, but get it just right.
Torque the top clamp to spec, go for a ride.
As we all know, nothing worse than tight balls!
Yeah that's basically how I do it. Pretty confident that I'm in the ballpark. But I'll see what loosening or tightening does.
In the mean time I checked all the engine mounting points.
Swapped the front fender for the stock steel one.
Might be able to do a small test run today
In the mean time I checked all the engine mounting points.
Swapped the front fender for the stock steel one.
Might be able to do a small test run today
Max Midnight
XS650 Addict
I use a spring balance to make sure that the torque doesn't increase as the nuts are tightened.
You need to have the top yoke off, front wheel off the ground and with the bars to the left or right. Attach the spring balance.
Pull the balance so the bars come to the central position and note the reading on the balance or loosen it if more effort is required to turn the bars.
Put the bars back to the left or right and start to tighten the lock ring. Keep pulling the spring balance until to are back to the first reading.
Put the top yoke back on but don't tighten the pinch nuts.
Tighten the top nut until you get the original reading. Torque the pinch bolts.
IMO this is the best way to ensure additional torque is added to the bearings.
You need to have the top yoke off, front wheel off the ground and with the bars to the left or right. Attach the spring balance.
Pull the balance so the bars come to the central position and note the reading on the balance or loosen it if more effort is required to turn the bars.
Put the bars back to the left or right and start to tighten the lock ring. Keep pulling the spring balance until to are back to the first reading.
Put the top yoke back on but don't tighten the pinch nuts.
Tighten the top nut until you get the original reading. Torque the pinch bolts.
IMO this is the best way to ensure additional torque is added to the bearings.
That high front fender is one potential culprit. This is a known phenomenon with dual sport/ adv bikes at higher speeds.
Also, two pretty large brake discs add mass, which in turn will lower the front ends natural harmonic frequency. Which may allow oscillations to develop.
Pretty much everything is related/ connected to everything else.....
Also, two pretty large brake discs add mass, which in turn will lower the front ends natural harmonic frequency. Which may allow oscillations to develop.
Pretty much everything is related/ connected to everything else.....
Tire pressure matters also.
Out west on a dresser that picked up a screw in the rear tire.
Started out fine at 80+MPH, then it started to weave (felt like the bike had a hinge in the middle) at this point I had no idea I had a slowly deflating rear tire.
65 miles of freeway with NO exits or services. Slowed to 75 it was fine, as the miles to the next exit SLOWLY wound down so did my "not weaving" speed.
By the time I was finally able to exit I was down to 50MPH
When I was able to get off in a gas station parking lot the tire was completely flat, I think centripital force was the only thing that let me keep rolling.
Very interested in your fender change experiment!
Getting rid of the "beak" on a uly a popular change.
Out west on a dresser that picked up a screw in the rear tire.
Started out fine at 80+MPH, then it started to weave (felt like the bike had a hinge in the middle) at this point I had no idea I had a slowly deflating rear tire.
65 miles of freeway with NO exits or services. Slowed to 75 it was fine, as the miles to the next exit SLOWLY wound down so did my "not weaving" speed.
By the time I was finally able to exit I was down to 50MPH
When I was able to get off in a gas station parking lot the tire was completely flat, I think centripital force was the only thing that let me keep rolling.
Very interested in your fender change experiment!
Getting rid of the "beak" on a uly a popular change.
I like my beak haha. Unfortunately too little time for a test run today. Btw I like that buell you got! Could that be a daily?
Like that method max! Ik recall some Manuals even State using a spring balance to check the force. I'll see if I can find one to use.
@artic yes I know everything is related haha. Makes finding the reason for my troubles even harder. Yes I have a double disk. And calipers, but these combined weigh less than one OEM disk with caliper....
I just received the scale and was able to do a quick check.
tank of gas is about 2/3 full. Just the bike.
Front weight: 93,5 kg (47%)
Rear weight: 104,5 kg (53%)
Might to another measurement with me on it, to see what that does. Anyone know the original weight distribution?
Like that method max! Ik recall some Manuals even State using a spring balance to check the force. I'll see if I can find one to use.
@artic yes I know everything is related haha. Makes finding the reason for my troubles even harder. Yes I have a double disk. And calipers, but these combined weigh less than one OEM disk with caliper....
I just received the scale and was able to do a quick check.
tank of gas is about 2/3 full. Just the bike.
Front weight: 93,5 kg (47%)
Rear weight: 104,5 kg (53%)
Might to another measurement with me on it, to see what that does. Anyone know the original weight distribution?
O and regarding tire pressure, I've been running around
Front: 2 bar (29 psi)
Rear: 2,4 bar (35 psi)
That's with tubes
Any references?
Front: 2 bar (29 psi)
Rear: 2,4 bar (35 psi)
That's with tubes
Any references?
My V-Rod has tapered head bearings and they are extremely susceptible to tightness, lubrication and condition.
HD is notorious for under lubrication of chassis components during assembly and very early water ingress to the head bearings would initiate rust creating a notchiness that induces a wobble, which is very difficult to feel assembled. There's a standard procedure they call a "fall away" check where you get the front wheel off the ground and tighten the head bearings till when a certain angle of turn is induced that the fork assembly falls to either side.
What I discovered is that the extra weight of the wheel and caliper assemblies on the fork mask the conditional feel of the head bearings.
By put the front wheel off the ground and removing the wheel and caliper assemblies from the fork I could turn the bars from side to side and you could more easily feel roughness in the head bearings that could not be felt with the additional weight of those components.
I realize that you're running balls rather than tapereds but the premise is the same. Raise the front, remove that extra weight and carefully rotate the bars side to side and verify that there are no lumpy spots. Just a suggestion.
HD is notorious for under lubrication of chassis components during assembly and very early water ingress to the head bearings would initiate rust creating a notchiness that induces a wobble, which is very difficult to feel assembled. There's a standard procedure they call a "fall away" check where you get the front wheel off the ground and tighten the head bearings till when a certain angle of turn is induced that the fork assembly falls to either side.
What I discovered is that the extra weight of the wheel and caliper assemblies on the fork mask the conditional feel of the head bearings.
By put the front wheel off the ground and removing the wheel and caliper assemblies from the fork I could turn the bars from side to side and you could more easily feel roughness in the head bearings that could not be felt with the additional weight of those components.
I realize that you're running balls rather than tapereds but the premise is the same. Raise the front, remove that extra weight and carefully rotate the bars side to side and verify that there are no lumpy spots. Just a suggestion.
Looong story but yes it's now a daily and other considerations aside, the bike I'm most likely to pick for a ride.
your weight? Unless you're big guy; 35 in the rear might be a little hard? front sounds "about right"
I've kinda headed towards 30 front and rear on the XS's
notchy races on ball bearing are SO common.... Would that contribute? mebby once races have been diturbed.
Those later yamaha stem nuts use a rubber bushing between the nuts and a retainer to lock in the setting.I think the idea is to avoid changing preload when locking with the second nut.
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Cycle World Road Test of the '70 XS-1 said the weight distribution was 45/55.
https://magazine.cycleworld.com/article/1970/3/1/yamaha-xs-650
