Wandering symptom - possible causes

[dbbrian]

I met up with a few vintage bike guys last night after a 45 min ride. Rode home late (first time on this bike in dark) with a vintage guy on a vintage '59 Triumph 650.

I was kind of embarrassed with my struggle to maintain a straight line on the highway, especially since I led the wy with my superior lighting system over the Bonneville.

Could be my tire - it is a Chen shin(spelling?) with what looks like a raised centre ridge. I think I hate it.

Could it also be the headstock bearing?

Or something else? Would fork brace help, or steering brace? (little known subject for me) or rthe big honkin' fairing? Was some wind but not much.

Or maybe I'm just a crappy driver - but I don'r recall having this difficulty when I used to ride in the past. No worries about saying it - my feelings won't be hurt if you think that.

Thoughts?

[JeffH]

- but I don't recall having this difficulty when I used to ride in the past.

Thoughts?

Being the diagnosis with the basics. What is the front tire pressure? The rear tire pressure? What kind of pavement and its condition. Acting odd at what speeds?

Anything new on the bike? Any recent work or maintenance?

Yes, steering head grease & adjust or new bearings can make it better but if it was fine in the past then I'd question if its not just tire psi or road or out of balance wheel. Easy stuff first.

Jeff

[dbbrian]

Tire pressure - I forget exactly, but I know I was shy to put in too much being the tires are 8 years old. Maybe 32 lbs

What pressure should I shoot for? Rear is a Bridgetone.

Bike is new to me. No recent changes by me. Always noticed some wandering with wind, thought the issue was the fairing, but I have been kind of relaxed about my road position, out on local country side roads with varying conditions. Definately notice the tire wander when pavement is uneven - like depressed tracking or lapping pavement

But with a partner nearby I was trying harder to be steady and struggled.

[Bonz]

Like you said, don't be a crappy rider, but I don't think that is it. You don't want to be a crappy bike owner . Check your equipment before you ride if there is any doubt.

Has it been so long you don't remember what psi you did set them at? And "shy" about putting more air in the tires because they are "8 years old"? But you are more than willing to trust them to stop, turn and accelerate under you by virtue of riding on them?

Tires are inexpensive for these bikes, maybe a new front for sure is called for.

Think about why you won't air them up, and then you would go ride on them without truly knowing how much air is in them?

"Tire wander": Could be tires with uneven wear, also if the tread depth is getting low the front will wander more, or low air pressure and the tire follows every groove and line. And heck yes, if you don't know what pressure they are at, please check that before you ride next time.

With that said, my head bearings needed servicing and that got rid of a low-speed wandering but was always steady at more than parking lot speed.

Is the fairing on straight and true? If not, could cause front end to wander around as it cuts through the wind as you try to go straight.

[MaximPhil]

Hi Brian,
Following JeffH suggestions. I would increase the front pressure to 38psi after examining the tire for any irregularities. TEST after every change so you know what was causing it.
I have a fairing on mine and do not have an issue with wandering in the wind.
Check the steering head for slop or play.
Do you have a manual? If not go to any post by member Catatonic Bug and look in his signature for the link to down load. see Chapter 2-18 for Test and adjustment of Steering head bearings. see Chapter 5-14 for cleaning / replacing bearings.

I would change that tire anyway
https://www.canadasmotorcycle.ca/shinko-712-front-tire.
Zdeno in Kitchener have lots of tires too.
Mounting is always cheaper if you take the wheel off your self.

Report back with results

Phil

[ViperRon]

One possible big mistake many make is having one of those old slide tire pressure tools or a new plastic one. I have seen these things vary by more than 15 lbs pressure. On these bike 5 lbs makes a big difference on some roads. If pressure is too high and you hit a slick spot in a curve it can get away quick. If tire is low the bike will wonder all over the road and follow every crack. On grooved cement it will take you all over the place and at high speed a tire wobble can be a very bad thing. Make sure you have a good gage that 1.00 thing may be great or a piece of crap do not risk it.

Bad bearings misadjusted front fork bad shocks all amplify these things so it may be a combination of things. Check your fairing and see that it is solid mounted if it has a lot of shake or flex it could possibly give you more problem in wind.

Tires that are old can be an issue but what is more important is what they are exposed to. Sitting out where sun and rain hit them decays rubber quick. Running in a city where the streets have a lot of oil chemical and gas residue can eat up tires as well as the chemicals for snow and dust treatments like calcium chloride eat up rubber.

Other important question is how many beers did you have that can have an effect.

[DiverRay]

From my side, as someone who rode a bike with OLD tires, that would be my first thing to fix!
Second is check the bearing while the front end is up for the tire change, and also loosen and re-tighten the front forks to be sure they are not tourqued.

[TopCatGr58]

All good stuff listed here. My bet is the steering bearings. The bike is NEW to you. Where and how was it stored?? IF outside, then just rain exposure can eventually get down in the steering neck and degrade the grease. I parked mine in '92 when the tranny went bad, the cover rotted, and it was exposed to the weather for 8 years. When I finally got around to rebuilding it, the steering felt very notchy and I thought it had rusted badly there. When I took it apart, pulled the bearings out, thoroughly cleaned them...the grease had turned into what looked like charcoal. The races were not rusted, nor notched. Once they were repacked and installed, the steering was a smooth as butter! There's a good chance that the steering grease is 38 years old.

I realize that it will be a bit of a PITA to have to pull the fairing off, as well as the handlebars, steering assembly to get to them, but pretty sure you'll find that they needed it.
When the steering head bearings are tight or sticky, the bike can't self center/correct/stabilize it's balance, and you have to constantly have to re-correct the line because it ends up oversteering since it can't CASTER itself.

T.C.

[BA80]

8 year old Cheng Shin tires aren't going to help either.

[skids]

Front bearings adjusted too tight makes it feel like you are on a balance beam. Swing arm bearings that are too loose make it feel like the rear end is sliding around as you negotiate tight turns.

[dbbrian]

Wow guys - thanks for all the great feedback.

I am away for the weekend so the bike is parked at home.

No, it was not that long ago that I checked and touched up the pressure - just have you-know-what for brains sometimes with my memory. Think I've burned out the hard drive with too much work stuff lol. I recall looking at the max for the tire and thinking I don't want to go to the max. and stayed below, probably too far below. Definitely not up to 38 lbs. I just bought a new dial guage tester - think its decent quality, and checked against known pressures and another gauge.

No - no beer or anything else to intoxicate. Just coffee.

I think its time to get the tires I wanted to buy from the start. Pretty cheap really. I'm getting over the initial cash outlay for bike, insurance, inspection, gear (ATGATT) tune up stuff, etc. Going to do the Shinko 230 Tourmasters for more weight capacity - wanted the to get a 110 fromt, but measured the fender and looks like 110 is too big.

I have the service manual. I did tilt the bike back to test the steering head, but will try it again. The original owner parked the bike in his kitchen till 2009, then 2nd owner parked in a garage. Appearance supports this story.

I will go over it thoroughly when I get back with all these comments in hand to check things and report back. Thanks - - great forum / great members!

[jetmechmarty]

Chen Shin was crap when it was new. I can't imagine what an old one is like. Probably dangerous. 100/90-19 is the correct size. Why mess with it? If the 110 runs true to size, or big, it's not going to fit or it will damage your fender when you pick up a rock? Many brands run small and you can cram them in there. The proper size is going to handle better than oversize.

Fork brace isn't going to do anything for you. It keeps the bike on the line during hard cornering. You aren't going to do that with ancient Chen Shin tires. The fork brace helps most if you go to tighter front springs. With bumpy Canadian pavement, I wouldn't expect them to be a priority.

[Bonz]

I am running the Shinko 230 Tourmaster front and rear on the 80SG. Couple thousand miles on the front, just put the rear on a hundred miles ago. I like the higher load capacity as well vs 712's.

[skids]

I have run the bikes on low pressures (like 10 psi low) and it does not seem to be any big deal except for abnormal wear... The wear profile, like tread worn badly around the center will make it kind of "twitch" into hard turns. New rubber can make all the difference if that is the case.

[JMilliken]

Your tires are way too old

I have heard as low as 4 years on tires

http://blog.unsafemotorcycles.com/20...tters.html?m=1