Good evening all. 

after my ignition spark success I thought I would give the bike a go.  Fuel on. Couple of light kick overs to hopefully get some fuel going. Motocross boot on and  Went for it.  Mechanical noise from clutch side case best described as a type of clunk and a smell of a potential “pop” and kick start returned. Now won’t engage to turn engine over. I am due a break with this bike. 

kick start just rotates without engaging.   Removed clutch cover.  Kick start gear turns ok.  The gear that engages with turns ok.  That gear disappears behind the clutch.  It is here the problem is. It turns without engaging until it’s done a full engine cycle then tries to engage but seems to slip out of mesh with whatever it is. Clutch seems to jump forward a few mm. Then the gears just turn not engaging with anything. Repeat. 

I don’t know what it’s not engaging with or why. I guess it’s a clutch off job?  I have tried to attach a photo. Gears 1 and 2 turning ok. Whatever gear 2 engages with is the issue.  

it’s a test of my patience this bike. All pointers, as always, welcome.  

thanks. 



share.icloud.com/photos/0a725MW1oK89smX1ZBpDBdPJA

Have a linked my whole library or just one photo? Could someone let me know please?

I can only see one photo.

Sorry should have said 1970 RT1.

Not sure if I can change a thread title. I can’t see how.

Thanks

Fixed title.

Sounds like gear behind the clutch broke?  (#18 here: www.partzilla.com/catalog/yamaha/motorcy...970/rt1/transmission)

Thanks markt. Appreciate the title change.

You must all be sick of me. Could it be part 17 the circlip? On inspection after your suggestion the clutch basket moves outwards as a complete item effectively disengaging that gear you mention. If I push the basket back towards the cylinder the gears seem to engage and try to turn but the basket jumps forward and it disengages. Not a great description but hopefully you know what I mean

Will have to remove the clutch and take a look. Do I need special tools for the clutch removal? Sorry, being lazy. I can’t see how look up that process.

i wonder if the clutch basket nut is loose?  Soon find out I guess.

Many thanks. Ian

Hi all,

Update. Got my service manual out and the spanners. I don’t have a clutch spanner but one is on order. Just thought would get as far as I could. Lots of oil sediment at bottom of case from clutch friction plates I think. Removed pressure plate. Then I could see the boss nut. Which I could turn with my fingers! Removed boss. Plates are not nice. I measured the thicknesses and are in tolerance of 3mm - 10%. But think will change them. See pictures hopefully attached. Also get new cushion rings whilst at it

Will also change clutch springs as at limit 36.4 in book. Mine 35.3.

Seem to be missing a rubber friction ring that goes between the primary driven gear and clutch housing. Will try to source from usual places.

Not sure if the thrust bearing is there on the crankcase side of the primary gear spacer. Will have to remove the kick start idler gear to check. Unable to find circlip pliers just now. Spacer is there just can’t see if bearing there .

I moved on to the primary gear and that too was hand tight! Some has forgotten to tighten things up after being in there.

Kick start assembly all came out in one go including the spring. Looks ok.

All the gears look ok, which is a result.

So awaiting me getting round to ordering some new parts. And finding circlip pliers and receiving the clutch tool to reinstall.

Questions? Should I do anything else whilst I am so far in on this side? I do have new crank seal that I could fit. Genuine Yamaha. Daft not to? Easy to do?

Take a look at the photos and let me know if anything looks amiss or you think I should address please.

Thanks ever so much, ian

share.icloud.com/photos/0abZSP31X-8Cjl5wcRZH-4sLA

You might want to take a file and try to smooth out the grooves in the fingers of the clutch basket. Those are pretty deep so you may not be able to remove them completely.

Thanks schu.

Yes they are deep aren’t they. Not sure how much is safe to take off. I have never done that job before. This bike has had some use I fear over the years.

Thanks, ian.

I’ve filed several clutch baskets on my bikes and it is an easy task. I use a medium to fine file which seems to work best. The ones that were really grooved I simply filed them down to the point where all you see is a small witness mark being what’s left of the deepest portion of the grooves. The edges were gone and it left a relatively smooth surface. I do this with the basket removed and in my lap. You need to flush it all clean because there will be a considerable amount of aluminum dust from the file. I’ve heard others say you can get away with doing this one time. But after that you are best to replace the basket with one that is in better shape.