Hi all! My Gas Gas JTR clutch is not working. Unfortunately my package is slipping, I measured exactly 27 mm. 0.3 less than expected, maybe that’s why it won’t work? If you give it gas, the revs increase and there is vibration, but the motorcycle doesn’t move. It only works in 3-4-5-6 gears and maybe the springs have sagged, can you tell me what size they should be?

1 hour ago, lineaway said:

Did it sit for a long time or did you just work on the clutch. Tell us the whole story.

The motorcycle is 30 years old, I am the 4th owner. I bought a separate motor, the old one was not working properly. I bought the engine from an auction in Japan. I tried motul 10w40 oil for the motocross gearbox. Then I tried Putoline RS 75 oil. It didn’t do anything, I thought maybe the wheels were slipping because of the oil. I found a video https://www.youtube.com/watch?v=oK4q6eJLC-s my discs are 0.3 mm smaller, maybe that’s why the clutch doesn’t work. When I give the gas, the engine speed increases, the engine spins up, there is a lot of vibration and the motorcycle does not move!

I forgot to write it down, it more or less drives in 3 gears, but works in 4-5-6. It doesn’t want to go to 1 and 2 at all, the front wheel won’t lift

Edited September 26, 20241 yr by nick1

Have to ask because you didn't specify; any chance you over-filled the transmission oil capacity?   

2 hours ago, lineaway said:

Well have you taken the clutch completly apart. Those old plates were known to come apart. The friction plate glue would give out and and you could just pull the friction msterial right off the steel.

 Also the clutch basket can only go together one way. There is a notch on one of the clutch fingers that aligns with a mark on the pressure plate. 

yes, I assembled according to the mark, I know that the basket should be in only one position.

1 hour ago, lemur said:

Have to ask because you didn't specify; any chance you over-filled the transmission oil capacity?   

poured 700 ml

3 minutes ago, nick1 said:

poured 700 ml

Can't tell from here but if the clutch basket is swamped the oil level is too high.  Another thing to inspect and clean is the spaces between the clutch pad friction pads, if oil can not evacuate from inside the clutch pack then hydraulic action can keep the clutch from engaging.  

7 minutes ago, lineaway said:

700 is fine., Bit did you have the clutch plates out.

I removed the clutch and checked its size, the overall size is 27 mm, but it should be 27.3-27.9, I have 0.3 mm less. I assembled the clutch correctly. Like the YouTube video.

5 minutes ago, lineaway said:

So if it is assebled right. Now the question is do you have free play at the clutch lever?

I bought a new  clutch machine. The handles are free to move.

1 hour ago, lemur said:

Can't tell from here but if the clutch basket is swamped the oil level is too high.  Another thing to inspect and clean is the spaces between the clutch pad friction pads, if oil can not evacuate from inside the clutch pack then hydraulic action can keep the clutch from engaging.  

I have a 1994 engine, it looks like you need to pour 700 ml of oil. Or less? I checked the clutch discs are intact, the feredo is not separated from the metal.

I was not questioning the friction pads being intact, the other guy was, it's the spaces between the pads I had question with and I asked if the clutch pack looked swamped.   If oil can not evacuate from inside the clutch pack then hydraulic action can keep the clutch from engaging.

1 hour ago, lemur said:

I was not questioning the friction pads being intact, the other guy was, it's the spaces between the pads I had question with and I asked if the clutch pack looked swamped.   If oil can not evacuate from inside the clutch pack then hydraulic action can keep the clutch from engaging.

In what space do you mean? Can you take a photo so I understand? Do you mean maybe the feredo itself, there are grooves there, are you asking about them? I am writing to you via Google Translate

If the spaces between the friction pads become clogged with friction pad material or if the oil level is way too high oil pressure can happen that pushes against the springs.  It is one of the scenarios that can make a motorcycle clutch slip.  Yes to the groves needing to be clear so that oil can pass through, some times it is very obvious on inspection where the groves have become plugged with fibre material.  

Thanks everyone for your help! I bought 5w30 mineral oil and machined the rings so that the springs would press the clutch harder, but it didn’t help. The problem is probably in the carburetor!