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-   -   My bike unstable? (http://www.horizonsunlimited.com/hubb/yamaha-tech/my-bike-unstable-63839)

bikereurope 20 Apr 2012 08:55

My bike unstable?
 
i have a 1991 xt600 3tb.

I have never ridden any other bike (since learning many years ago) and therefore i have nothing to compare with.

When i drive my bike in corners and around in speeds under 70-80 kmh its stable and predictable.

when I'm driving on the highway in 80-90 kmh it doesn't feel that stable. its okay when i do slow movements, cornering etc. but if i do small and hard movements on the handlebars (like movements so hard that i wouldn't normally do them )the bike feels unstable. the bike doesn't go into a wobble, (whitch i have never experienced ) but i think this could be a pre stage to one? the bike shakes between my legs. Im afraid that the bike would be unstable on me if i needed to do a quick turn at high speeds due to deers, cats etc.

i the tire pressure is ok

i have a big box on the back, its has only 3-5 kg of luggage,(oil, chain lock etc)

i changed fork oil last fall.


new front and rear wheel bearings last year.

for all i know this is how these bikes handle?

any pointers? is this how these bikes drive? or should i check something?

Panzer 20 Apr 2012 10:13

My TTR600RE is terrible on motorways it wanders about and have to hold on for my life and thats below 70mph and lower if windy.

Tenere Tom 20 Apr 2012 11:57

Quote:

Originally Posted by Panzer (Post 376142)
My TTR600RE is terrible on motorways it wanders about and have to hold on for my life and thats below 70mph and lower if windy.

I agree, my XT600's all were terrible on the motorway.
They are not a motorway bike really...

kentfallen 20 Apr 2012 14:57

Agree with above posts - The Yamaha XT600 series of bikes (all models) are not designed for riding at those quoted speeds.

My bikes cruise happily all day at 60 mph max. Higher than 60 mph they feel unsteady. Although it's possible to touch the ton just... (flat on the tank with assistance of the wind on a long straight), it's not to be recommended for longer than a few moments!

Ride your bike within it's designed safety margins (max 60mph) and all will be well. Tank it over this speed and be prepared for a spill or worse! :nono:

The XT6 is an awesome economy RTW bike nothing out there will beat it. It's reliablity and simplicity record is legendary. :thumbup1:

Where these bikes do excel is in town on B roads (relaxed countryside riding) and on light trails. Take them onto the motorway and they are less capable. A single cylinder bike without wind protection is never going to perform well above 60mph. I ride my bikes in the countryside (summer only) at speeds averaging between 40 - 50 mph and they take some beating. I like the high riding position because it allows you to see over hedges etc... I also enjoy the "grunty" low down torque the single cylinder XT engine produces...

Lastly if you ride at those speeds, your bike (and you) probably won't last very long. :thumbdown: If you are a speed demon then get something that will put up with that punishment and give better wind protection. Sounds like you need to get yourself a twin cylinder (or more) trail bike instead...

Some modern bikes (sports/tourers) are very capable at speed but you must ride well within your riding capability in order to stay in one piece. Never forget the country road killer - their might be a slow tractor or broken down car around the blind bend....

bikereurope 20 Apr 2012 15:18

thanks for your responses. i need to point that my speed was referred to in kilometers an hour, not miles. in miles the speeds I'm talking about is round 50 milesph.

i have owned the bike for 16 monts and this is almost the first time i have driven it on the freeway, the first time i noticed that it was so shaky.

John Downs 20 Apr 2012 15:46

It sounds like you have looked after the easy stuff like tire pressure, fork oil, wheel bearings.

It's time to look into the other common culprits.

My first thought would be worn swingarm bearings that allow the rear wheel to wag back and forth slightly going straight but track straight when leaned over in a curve and forced to the side. On a twenty year old bike I imagine it is a combination of things, steering head bearings worn or slightly loose, possibly loose motor mounts, worn rear shock, rear wheel slightly off square to the frame.

Add to that a top box on the back catching air at speed exacerbating things and the old bike starts riding like she's been drinking again.

People in third world countries who are too poor to fix these things slow down or else learn to dance with drunk bikes. You are hopefully able to tighten things up and get a more stable ride.

Best luck.

Kindest regards,
John Downs

bacardi23 20 Apr 2012 19:34

Or it can be just that piece of crap front fender it comes with!

After I replaced my front fender with one of an YZ250 I ride above 120 k/h and there is no wobbling or whatsoever......

Jens Eskildsen 20 Apr 2012 20:51

Which tires, they make a world of difference. My knobbies wander all over the place at 100km/h, but my streettires are just fine.

An easy way to make the frot more stable is to raise the forks, so you lower the whole front end, and push more weight on it.

Have you tried to remove the topbox to see if it makes a difference?

Fern 20 Apr 2012 22:09

wheel balancing doesn't cost a lot. I balanced my rear tyre and it went from being a psycopathic demon above 50mph to bearable, just by swinging the tyre loose on the spindle in the swingarm and sticking weights on myself. Could be that, but 50kph? That's nothing. umm.

eeyore 19 May 2012 13:50

Hi, bikeurope. Just going through the same problem myself. I have a TTR600RE and have previously owned an XT600 which I went to Morocco and back on. First off I found my XT very stable at motorway speeds when fully loaded. Secondly, the only handling problems I've come across so far on the TTR have been due to the rear tyre - poor quality/balance. An easy test is to raise the rear of the bike on a stand - so that the rear tyre is well clear of the ground and the front tyre is touching the floor. Start her up and engage first gear, rev gently and observe the front end. Any rear wheel/tyre imperfecrtions that affect handling will show up in the forks as you increase revs to the speed equivalent on the road (ie whatever the revs are when you get the problem). Rear tyres are easily overlooked as a source of handling issues, but it's easy to check and easy to fix. Good luck and make sure you buy good quality tyres.


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