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Hello,

I’m from India and i just imported a new Bandit 1250S. The bike is over-steering a lot and it’s very scary to corner with the bike behaving like this. I drop my speed down to 20-30kmph while cornering just to ensure I don’t fall off. The bike just wants to dive into the corner as soon as you turn the handle.

Since I’m in India, there aren’t many good technicians I can go visit for such a bike. All we have here are basic 150 - 200cc motorcycles and hence I’m going to attempt to adjust everything at home, by myself, I have access to a workshop.

I’m 6'2" tall, weigh in at about 100kgs. Do I need to tune the suspensions according to my weight to rectify this problem?
I have done just 170 kilometers in the last 20 days that I have the bike, it just feels very front heavy.

Thanks for taking a look and for your suggestions.

Is the bike new or used? Has it just started doing this or when you first owned it as well? Are the front forks straight and inline?

If it's not any issues above and it is just turning too freely into corners you can always pick up a steering damper:



But I would go for the inspection route to make sure the frame/forks are normal and the tire is ok too. If so, then it's just a quick turning bike that you will just need to get used to.

Mike


:Steering damperFrom Wikipedia, the free encyclopediaJump to: navigation, search
A steering damper, steering stabiliser or sprint damper is a damping device designed to inhibit an undesirable, uncontrolled movement or oscillation of a vehicle steering mechanism (a phenomenon known in the motorcycling community as 'wobble', or in extreme cases, a 'tank-slapper'). Modern motorbikes are unlikely to exhibit this behaviour in daily use thanks in part to better dampers and due to their very stiff front ends and other general improvements in design and tyre technology.

[edit] Device usageSport bikes have a short wheel base and an aggressive steering geometry to provide the ability to make very quick changes in direction. This has the generally undesirable side-effect of making the bike less stable, more prone to feedback from uneven road surfaces, and more difficult to control.[1] In addition, their light weight and powerful engine can cause frequent wheelies. If the front wheel significantly deviates from the direction of travel when it touches down, it may cause an unwanted wobble. Steering dampers are factory installed on some high-end sport motorcycles and fitted to most contemporary racing bikes to counter these behaviours.

Steering dampers are also mounted to off-road motorcycles such as motocross bikes[2]. A damper helps keep the bike tracking straight over difficult terrain such as ruts, rocks, and sand, and also smooths out jolts through the handlebars at the end of jumps. They also reduce arm fatigue on longer rides by reducing the amount of effort needed to control the handlebars.


Transverse linear steering damper (centre foreground)On motorcycles, one end of the damper mechanism is mounted to the steering yoke, the other to the frame. Steering dampers are available in two forms. Linear dampers resemble a telescoping shock absorber and operate in a similar manner. They can be aligned either longitudinally and to one side of the steering, or transversely across the bike. Rotary dampers resemble small boxes and operate via a rotating pivot. They are mounted coaxially with the steering axis and are typically located on top of the steering head.

For motorcycles with sidecars, especially for solo motorcycles which have had a sidecar installed later and where the front wheel geometry (trail) has not been adjusted for the particular use with a sidecar, the installation of a steering damper is highly recommended and extremely beneficial. This prevents low speed wobble which may occur in the lower speed range of about 13 to 20 mph. In older motorcycles adjustable friction dampers had been routinely installed. Hydraulically operated steering dampers may be retrofitted. The installation and operation of a steering damper must be inspected by an expert or examiner and must be entered in the vehicle papers. [3]:"

Mike

its a brand new bike and it felt like this the moment they took it out of the shipping crate. it had 0 (obvious) kilometers on the clock and since then I've been calling the Suzuki guys to correct it. They say its the suspension which needs to be adjusted to my weight and riding style. I'm thinking of stiffening up the front and softening up the rear? good idea?

Yeah that's one option. Get the bike up on a centerstand or a lift and check the front bearings. From the fork to the wheels to the steering stem. I'd guess it's in there if it's that bad. Otherwise yeah stiffen the front and soften the rear.

Asking the obvious here: How is the tire pressure????

Yea, try 2.75 kg/cm² in each tire.

the tyre pressure is as recommended (36Psi front and 42Psi rear). I cant find anyone knowledgeable enough to adjust the setup for me so im downloading the workshop manual, i guess that has more details on how to adjust the suspension. if i do it by myself, what do i need to tamper with to get the bike 'nose up'? the rear shock has 7 levels of spring settings and one small screw at the bottom for adjusting 'hard' and 'soft'.

Your description of the problem is puzzling. Oversteer and dive are not usually mutually co-existing. Oversteer is usually the result of a stiff front end but a dive is the result of a soft front end.

HYPERR wrote:Your description of the problem is puzzling. Oversteer and dive are not usually mutually co-existing. Oversteer is usually the result of a stiff front end but a dive is the result of a soft front end.

i just figured it out. my whole damn suspension setup is wrong. the mechanic who delivered the motorcycle to me had no clue about such motorcycles and fiddled with the stock setup.

im taking a break from work tomorrow to sort out the whole setup. Can someone please tell me what is the average suspension sag for the bandit 1250S?

I've got access to the manual.
It doesn't say average sag, but for the rear suspension it says the adjustment should be 1 and 1/4 turns out from the stiffest setting for a standard setting.
Also on the rear it says the position of the collet at the top of the shock should be at the third position on bikes without ABS and on the fourth position for bikes with ABS.

For the front suspension it says the spring adjuster should be in the third groove from the top.
Depending on if you have the ABS or not the front oil level should be at 143 (without) or 144 (with) mm of oil with the spring out and the outer tube fully compressed.
The front fork oil capacity is 472 ml (without abs) or 471 ml (with abs) as well.
And your spring free length should be a minimum of 382 mm and an average of 390.4 mm.

Hope that helps buddy!