What if?

[Red Dog]

Hypothetical question:

If your scooter engine suddenly sized solid while doing 70mph on the motorway, would it lock your rear wheel or would the variator let go allowing it to run free?

[Ralph]

The front pully weights would stop with the engine and the front pulley would loose
a lot of it's grip, allowing the belt to slip, the scoot would slow down quite quickly
but not lock the wheel,

[Data]

This has actually happened to me during my tech days whilst dyno'ing a Honda 600 Silverwing. The bike of course was tethered (thank goodness). As I accelerated quite hard, the rear wheel ACTUALLY LOCKED momentarily at 60mph. Due to tethering the bike remained upright and ok. Slight heart stopping moment though! The bike broke a piston with an immediate seizure resulting.

So, why did this happen? Well, it can happen on any scooter with this type of transmission. The chance of it being a problem though is relatively low. It seems the faster you are going and the more throttle that is applied at the time, the more likely it is to be more of an issue. It will only be a momentary lock up but if you are doing 60 mph or more you can travel an awful long way in a second (88ft in fact). That means you may be skidding for a good few feet before the variator finally lets go because not all the weights suddenly drop back to the centre of the variator hub. In addition the clutch has to let go too. In some testing we did afterwards we showed that it's the clutch that is the last thing to let go preventing the rear wheel from spinning freely. In effect the reason I skidded was due to the marginal delay of the variator and the clutch letting go. That's all. It's usually not just a simple dropping of the variator weights that will let you off the hook. There is always this slight delay. I hope no one suffers this on the road.

[Red Dog]

Thanks, I appreciate it.

I've been thinking about it recently because a good Suzuki mechanic who did some work on my bike told me that he thought it sounded very slightly "Bottom endy"
His mate disagreed and said they all sound like that.
Both said "Don't worry, it will be fine".

I must admit I've never noticed any change in the engine sound and I've done over 20 thousand miles on it.

I can't recall seeing any posts on the forums about Burgman's seizing up and chucking the rider off, in fact very few about Burgmans seizing at all.

[Scootalli]

I'd be more worried about the condition of the drive belt.

I had a friend who had shall we say, not a perfectly maintained burgman, who was on the motorway when the drive belt snapped.

He regaled to me the tale of terror and the need for some new underpants!

[Pandrop]

Way back in the nineties I had a chain give up the ghost whilst hammering a Kawasaki GPZ550 uphill on the M65 early one chilly morning and luckily for me it rolled itself from the sprockets at high speed and dropped straight onto the deck where it lay full length with steam rising from it. There was however considerably more steam rising from the rear of my leathers.

[Tartan Cobbler]

I had a chain let go on a ZXR 750 and it just ran off the sprockets and I fortunately coasted to a stop, endless smokes later thinking what could have happened.... never did find the chain

[MrGrumpy]

The real 'could have been nasty' moment was when a bearing between the CVT and final drive failed on the Tmax. I had very little warning that something was wrong then the rear wheel seized completely! Fortunately I was only doing 10 mph 10 yards from my house, but I dread to think what would have happened if it had happened in the outside lane of the M25! Presumably that's why Yamaha Japan got involved with the warranty claim...