Grinding sound on quick take-offs (first gear)

[calebxs]

All,

XS2

This issue started after replacing my clutch last season. It never happened before then.

When I put the bike into first gear and take-off quickly (high torque) sometimes I get this weird grinding sound from somewhere in the motor. I know that the word "grinding" immediately makes you think of gears, but I'm wondering if this also could be the clutch slipping. The bike also lurches when the grinding sound happens.

Quick facts on the problem:

• This isn't a switching gears and grinding problem like in a car. This happens when the bike is stationary, put into gear first, and then accelerated.
• If I ease into first gear (low torque) it never happens.
• If I have a second rider it happens more often (hauling extra weight)
• When I loosened the chain it improved the problem a bit (could take off quickly and sometimes not grind) -- chain was too tight.

I don't understand enough about the transmission to figure out what the sound is or what is causing it. I read that the MikesXS replacement clutch springs are sometimes not stiff enough so maybe it's my clutch slipping? Could it be my gears grinding even though the bike seems to already be in-gear?

Thank you!

 

[TwoManyXS1Bs]

Try a hard launch from stop in 2nd gear. If it does that grinding thing, double check the clutch washers and the clutch assembly.

If not, may need to open case and check the output shaft bearings, particularly the one on the right side, between clutch and kickstart...

 

[gggGary]

Clutch slipping is normally pretty smooth. All you usually notice is the engine revving and it tends to happen at higher RPM.

 

[calebxs]

2M,

I tried a hard launch in second gear and it made the grinding sound again. I'll take a look at the clutch later this week.

What did you mean by checking the washers?

 

[5twins]

There are spacer washers behind the main clutch hub and in between the main hub and the inner basket. There is also a flat radial bearing in between those two parts. They have a certain specific assembly order. Early parts drawings omit one of the washers needed in between the main hub and inner basket. There should be two washers with the radial bearing sandwiched in between them .....

You said you replaced the clutch? Exactly what did you replace? Just plates? The whole assembly? I ask because the plates in your early clutch differ from the later ones. Yours were 3.5mm thick, the later ones only 3mm thick. They say (MikesXS, but who can believe them, lol) you can use the later thinner plates if you add one more to make up the thickness difference. You would also have to add another steel plate. I've read mixed reports on that switch, some saying it doesn't work very well.

 

[calebxs]

5Twins,

Thank you for this. I only replaced the steel drive plates and friction plates. I remember when I changed them going through the struggle of getting the stack the right thickness.

I used EBC CK2242 clutch plates and EBC CSK14 clutch springs. I think I used 7 EBC friction plates (because they are thinner) and a mix of steel plates from Mikes and the original to get the proper overall thickness of the stack. I can't remember if it I had all original friction plates and one Mikes plate or all mikes plates and one original (i think the latter). I can verify based on what I have left over when I get home.

As far as washers and reassembly; I think I put everything back in the right order. I don't remember there being much to it once i got the old springs out and put the new stack in.

 

[5twins]

You can replace the plates without removing the inner basket or the outer hub. Just the pressure plate needs to come off the top. If that's what you did then you didn't disturb any of the spacer washers. I should mention though that your original steel plates are also a little different than the newer steel plates. Yours are slightly thicker @ 1.6mm. The newer ones are 1.4mm thick. I don't think there is a way to match the stack heights between the two versions, the math just doesn't work out. All newer steels and fibers add up to .4mm more than the old stack. Maybe that's OK, I don't know.

 

[xs650roadster]

Hi Calebxs, did you ever sort this out?

Many years ago I replaced just my friction plates and my 650 has done it ever since!

I need to sort it out now I'm semi retired!


Cheers, Phil.