6 replies to this topic

[BPilgrim]

Hello,

I'm having issues with the clutch on my 348. Firstly, it slips if I kick it through a compression, so to start it I use the decompressor to get it to TDC and give it a kick from there, that works. I tried adjusting it to give me enough bite to enable it to be kicked straight through, this worked, and then to test if it was now dragging, I put the front wheel against a fence (it's a good job), and knocked it into gear, even with the clutch pulled in fully, the rear spun.

After a lot of adjusting whilst it was firmly stuck against the fence, I've adjusted it so the clutch drag is bearable, I can't move the bike backwards in gear, but it doesn't move forwards on it's own anymore. Another problem with this is that you can't get it into neutral when the engine is running.

When the engine is hot however, this improves, so I'm thinking that it's just the oil? I was recommended to use modern gear/clutch oil, by a bike garage, I went in asking for the oil that the manual says, and they had never heard of it... They were also surprised to hear the clutch was separated from the gears...

Do you think this is just the oil? I've heard it could also be warped plates? What type of oil do you recommend, I've heard ATF being mentioned, any particular type?

Another thing I thought it could be was the travel on the cable/levers. I've got some standard/universal levers, are amal levers known for having more travel?

Thanks in advance

Ben

ps. What's the point of the breather of the RH crankcase cover?

[keychange]

I think the 348 is similar to the 247 and if you remove the clutch side covers you will see that a small metal plunger (about thimble size) is there and this pushes against the spinning mechanism to activate the clutch. The plunger wears out and your bike behaves exactly as described.

The plunger on my 247 did this 9 months ago and on mine it was steel so I laid some metal on with an arc welder and then ground it smooth on an oil stone - it is still working fine.

However just to be careful I ordered one from John Haberbosch Rocky Mountain Montesa only a a few days ago cost $15 and this one is brass ( which I believe is correct) his email is john@rmmontesa.com - great service and reasonable post etc - from USA to Oz..

[belldane]

That little brass plunger is the right one to use. However it can fit into that little slot that actuates the clutch either way. Only one way to fit it as the bottom sides of that plunger have different cutouts. Can't remember which way it goes now but I can check if you want. I have always used 10w 30 oil on the clutch side with no problems. As far as building up that plunger with a dob of weld, It may work for now but I would think that it is eventually going to wear the three pronged thing that it rests against and then you will be up for some new parts.

[BPilgrim]

Thanks for the comments, I have fitted the brass clutch plunger with the cut out into the hole in the casing, so the smooth end is pushing against the rotating 3 claw pusher.

I have just ordered some Morris Lubricants Golden Film SAE 20, which has been recommended for use in 348/349's. So I'll change the oil and if not, I'll order a new brass plunger from RM Montesa and see if that does the trick.

Thanks
Ben

[keychange]

This was my before and after - not pretty but it works. The correct plunger comes in various lengths for my 247 I ordered 8mm from the face to the cut away. If your existing plunger is less than 5mm - it is almost certainly the problem.

[BPilgrim]

Thanks for all of the advice, it was the plunger. My one's actually steel, but I checked my spare 348 engine and that had a brass plunger. The brass one was however quite a bit shorter so I used the steel one. There were signs of uneven wear on the 3 claw pusher, as if the plunger wasn't flush, but the plunger fell out when I took the cover off so I know it was in the wrong way, but I didn't know which way was the wrong way! So I played around with it and put the cover back on, and the travel on the clutch arm was much further. Topped it up with the Morris Lubricants oil and it's brilliant. I can now roll the bike backwards in gear, and can get it into neutral with the engine running.

I tried kicking it through the compression, it did slip, but that isn't too much of a problem, and it may get better after some running, and some more fresh oil.

Thanks for the help!

[keychange]

BPilgrim, on 28 January 2011 - 06:55 PM, said:

There were signs of uneven wear on the 3 claw pusher, as if the plunger wasn't flush, but the plunger fell out when I took the cover off so I know it was in the wrong way, but I didn't know which way was the wrong way!

You buy the replacement plungers in various lengths - my 3 claw pusher was also worn so I laid some metal on that with the arc welder and ground it flat - it too has been working happily for about 9 months .

Cheers