Clutch not engaging at all, will pull forward when put in gear

**tommorobo** · 11th November 2016, 10:48

Hi there,

I changed the oil of my bike and put in 80w for my KDX80 and the clutch is not engaging at all and will pull forward when i put it in gear and sometimes stall???
I have no idea what is wrong, any help would be much appreciated.

**Akzle** · 11th November 2016, 11:30

eighty weight.

are you fucking serious.

**OddDuck** · 11th November 2016, 11:36

Yep... check your manual and see what weight is suggested.

Higher weight number = thicker, more viscous oil.

80W is normally seen on gearboxes, not engines, and may contain friction modifiers. If it does and you're running a wet clutch then these modifiers may have messed up your friction plates. Wet clutches are why there's motorcycle-specific engine oil.

I'd suggest drain the oil (leave it draining for a full day if possible), put in the manual's suggested oil, run it and see if the problem's cleared.

I've got to ask... why did you put in 80W?

**ellipsis** · 11th November 2016, 11:41

...I also have to ask, why 80?...

**Ecstatic** · 11th November 2016, 11:58

Service manual says 10w-40, chuck that in and you'll be sweet

**Hemi Makutu** · 11th November 2016, 12:25

Originally Posted by OddDuck

Yep... check your manual and see what weight is suggested.

Higher weight number = thicker, more viscous oil.

80W is normally seen on gearboxes, not engines, and may contain friction modifiers. If it does and you're running a wet clutch then these modifiers may have messed up your friction plates. Wet clutches are why there's motorcycle-specific engine oil.

I'd suggest drain the oil (leave it draining for a full day if possible), put in the manual's suggested oil, run it and see if the problem's cleared.

I've got to ask... why did you put in 80W?

Its a 2-stroke, & the gearbox oil is not shared with the engine..
Specific transmission oil numbers such as "80W" do not directly co-relate with 4-stroke engine oil viscosity numbers.

I agree that he ought to follow the advice given in the manual.

**BikeNewb** · 11th November 2016, 13:07

What a Rat

**OddDuck** · 11th November 2016, 15:22

Originally Posted by Hemi Makutu

Its a 2-stroke, & the gearbox oil is not shared with the engine..
Specific transmission oil numbers such as "80W" do not directly co-relate with 4-stroke engine oil viscosity numbers.

I agree that he ought to follow the advice given in the manual.

Oops, OK. Should've checked before posting.

**Hemi Makutu** · 11th November 2016, 15:39

Originally Posted by OddDuck

Oops, OK. Should've checked before posting.

You are correct, 'friction modifiers' in car engine oil can make your wet clutch slip,
& maybe something in the oil he poured in, has caused the plates to swell/bind?

**Kickaha** · 13th November 2016, 05:38

Originally Posted by Akzle

eighty weight.

are you fucking serious.

Originally Posted by OddDuck

I've got to ask... why did you put in 80W?

There are plenty of 70/75/80 two stroke gearbox oils around, I used to use Castrol MTX in evrything which is an 80

Originally Posted by Ecstatic

Service manual says 10w-40, chuck that in and you'll be sweet

This is from Silkolene about their two stroke comp gear oil

SAE Rating 75W80 (Gear), 10W40 (Engine)

This is from Castrol about MTX

Specifications

SAE 75W-80, 10W-30

I'd check clutch free play for a start

**AllanB** · 13th November 2016, 07:29

Over filled it?

**T.W.R** · 13th November 2016, 08:39

New clutch friction plate pack required....the new oil isn't compatible with what the old stuff was....most likely mineral vs synthetic. The plates are saturated with the old oil.
Temp fix would be strip pack clean FPs with brake clean then dry completely then soak over night in new oil then reassemble...only as a temp fix.
Fresh plates soaked properly before assembly is the only proper remedy