Clutch Drum Rattle

[mark2yahu]

I got the roller (friction) drive kit yesterday from bikemotorparts.com, and installed it in a matter of hours. I had problems with the motor mount bolts being too long, so I had to find enough washers to use as spacers.

When I took it out for a test ride, I gave it a little gas. The clutch and clutch drum gave out a loud rattle, like a bolt hitting the clutch drum. The bike runs, the motor is good, but the clutch is really noisy. Only when I'm at full throttle does the rattling go away, so this tells me the clutch is fully engaged onto the clutch drum.

Now I'm thinking the clutch on the motor isn't compatible with this type of clutch drum. But they're both 78mm components. The motor is a 40cc Mitsubishi 2-stroke.

Can anybody tell me what's causing this rattling noise?

[vegaspaddy]

hi mark,

i had the same problem on my tanaka 2 stroke, if you adjust your idle screw one or two turns, (just behind the throttle cable connection) that should do the trick for you.

Mine sounded like a kids bell been rung every 5 seconds when the engine was idling but the adjustment did the trick, it was the clutch pads hitting the inside of the clutch housing, it would have eventually went away by itself but..... The bells The bells....

hope this helps.

[mark2yahu]

Vegaspaddy, you described it exactly: a kid's bell being rung! I must have set the idle too low. So, the clutch pads must be spinning fast enough that it's lightly contacting the clutch bell. Thanks for the tip!

[Boomer]

I noticed on my 66cc alot of noise coming from my clutch cover, it evidently must be an acoustic or harmonic noise, I can hold my finger in the center of the clutch cover and it stops, let up and it starts up again. Has anyone a solution for this problem? I thought I might spray some automotive sound deadner on the inside of the cover. I noticed one the vendors was offering a plastic replacement cover so it must be a problem on many motors.

[BoltsMissing]

Some have cut out carboard from a cornflakes packet and shaped it so it sticks on the inside of the cover, others have used an old mouse mat and cut it out to shape and stuck it on the outside of the cover.
You also need to periodically put some molly grease on the gears.
I did the outside option, but not used a mouse mat, but it's industrial strength synthetic rubber off-cuts about 1/8" thick. Works well.

[Boomer]

Some have cut out carboard from a cornflakes packet and shaped it so it sticks on the inside of the cover, others have used an old mouse mat and cut it out to shape and stuck it on the outside of the cover.
You also need to periodically put some molly grease on the gears.
I did the outside option, but not used a mouse mat, but it's industrial strength synthetic rubber off-cuts about 1/8" thick. Works well.

Great Ideas!
Rather than spraying that sound deadener in side the cover, I thought maybe it would find it's way into the clutch, I've got a thin piece of synthetic rubber I'll cut and fasten it with some spray adhesive to the inside of the cover and see if that works.

[Happy Valley]

The issues are confused here, though both valid.

The OP was talking about the bell or drum on a centrifugal clutch not the closed clutch on a HT engine.

[rossfree]

Boomer said, "I noticed on my 66cc alot of noise coming from my clutch cover, it evidently must be an acoustic or harmonic noise, I can hold my finger in the center of the clutch cover and it stops, let up and it starts up again."

Get someone to tape your finger tightly to the center of the clutch cover. That should do it!

Geeze... I crack myself up!

LOLOLOL

...sorry... couldn't help myself.

Ross

[Boomer]

The issues are confused here, though both valid.

The OP was talking about the bell or drum on a centrifugal clutch not the closed clutch on a HT engine.

Not confused for myself...I received a good answer to my question.

[Boomer]

Get someone to tape your finger tightly to the center of the clutch cover. That should do it!

Geeze... I crack myself up!

LOLOLOL

...sorry... couldn't help myself.

Ross

You can sure tell when the "kiddies" are out of school.