What causes a 'shudder' on Take-Off

My SWing just started doing something on take-off that it has never done before. When I accelerate from a standing-stop I get a very severe shudder. There is a very strong vibration throughout the entire bike that lasts a couple of seconds - but disappears entirely during a hard acceleration once I get going. There is no significant noise that I hear - other than maybe a vibration type sound. My typical ride lately has been about 300 miles. I noticed this shudder as being very slight 3 rides ago, then more noticeable 2 rides ago, and on my last ride it really started a very hard shudder and I came home and parked it in the garage until I can get it fixed. The SWing runs very smooth once it gets going. It exhibits no sign of any problem under any riding conditions once it gets moving and up to 75mph - it is very smooth like it normally is. I changed the belt 11,000 miles ago and have been running 24gram Dr Pulley Sliders. Most of my take-offs are under very hard acceleration. I plan to replace the belt today and see if that cures the problem. If it does not - then I will likely turn my attention to the clutch.

What do you think is the problem/cure? Is there any way to check on the condition of the clutch without taking it apart? Are all those 'special' tools (listed in the Honda Service Manual) necessary to get the clutch out and apart? Any pictorials on clutch work? Do clutches fail - or is that rare? I did a search but could not find any useful links - if you have any it would be appreciated (this site or other sites). Many thanks.

You don't mention (or I didn't see it) how many miles you have on your Swing. You also don't indicate how often you open up your CVT to inspect and clean it.

So just taking a guess from where you wrote that you changed the belt 11,000 miles ago, is perhaps the variator is gunked up. The inside where the weights move, will pick up belt dust. That will get to the point where the weights won't move evenly...and cause vibration.

Is there a spec for the CVT belt wear? On my Burgman 400, there is a wear measurement. The service manual also calls out for inspecting the belt for delamination. The maintenance schedule calls for inspecting and/or replacing the belt at 14,500 miles, but many people find their belt will last till at least 22,000 miles.

My point in that, is I wouldn't just change your CVT belt automatically, but would use the opportunity while you have the CVT open, to inspect and clean everything else.

How long has the clutch been in the bike? While a worn clutch might cause the symptoms you're finding, I'd expect more of a sound instead...like metal to metal. Still, it is worth looking at.

Chris

Dimond,

Just hold in your brake and then rev the engine up to about 4,000 rpms for about 5 seconds. You clutch is becoming glazed and this will 'de-glaze' the clutch. It is on old trick with the SWing and the Reflex. It will go away but you may smell a small bit of 'burning', but don't worry.

While you are replacing the belt its very easy to remove the clutch for an inspection.

The special tool is to hold the back wheel from turning, you can apply the hand brake and pull the back brake lever to stop it then you can loosen the centre nut. The whole clutch and rear pulley assembly can be removed in one piece.

JeffR_ wrote:

Dimond,

Just hold in your brake and then rev the engine up to about 4,000 rpms for about 5 seconds. You clutch is becoming glazed and this will 'de-glaze' the clutch. It is on old trick with the SWing and the Reflex. It will go away but you may smell a small bit of 'burning', but don't worry.

+1....as simple as that

Inspect well the slider/roller mechanic , behind the drive pulley.
Look for were on sliders and their slide channel.

A stuck slider(s) can cause your problem.
Because in that case, the drive pulley start not with the minimum diameter and / or a non-uniform weight distribution.


Eddy

Hats off to JeffR for diagnosing the problem and providing the cure! Who would have thought! Don't know why this is not in the Service Manual. I went from despair to bliss is 4 seconds! Everything is back to normal.

I did open the case and there was not much dust inside the belt casing and the belt was within the Honda wear limit.

Thank you RArch for advising me on how to remove the clutch as I may do this on the next belt change.

Thanks to Daboo and to Eddy for their input as well.

Hey Dimond,

I'm glad it worked and the SWing can get this 'shudder' if in really slow traffic. And since I see you are listed to be in S.F. it could be the stop and go and also the steep hill. I'm just across the bay from you in Fremont, so if you are ever up for a ride give me a PM. I also started a Bay Area riding group on Yahoo, but I don't really go on it too much at all anymore. Some may still be arranging rides all around the Bay.