Behind the clutch

[denis]

Hello all,
Could anyone please tell me how to remove the « thing » from under the 200 mark on the first pic so I can put it on the other engine?  It seems to be riveted in..
Which leads me neatly to the next question; do you have to take out the gearbox to replace the sprocket? Just asking, it seems in good nick but i’d feel stupid not to ask. 
Also, it seems to be the first time the clutch is out, any idea what the « 200  » means? 
I hope the pics came out alright.
Thanks in advance for your help,
Denis

[RDfella]

With the primary inner cover off, changing the sprocket is a breeze. As for rivets, I presume they hold the oil seal onto the case.

Ignore above post - just dawned on me it's a semi-unit plunger type so my comment does not apply as the case doesn't remove as with a S/A.

[denis]

Wow, quick reply!
I forgot to mention these are rigid and plunger engine, you can’t take the primary inner case off, it’s the entire half that would need to come off.

Cheers, Denis

[muskrat]

G'day denis.
Grind the heads off the rivets ans use small screws to hold it in.
To change the g/box sprocket the wholw lump has to come out and the g/box unbolted from the engine. So it's a good time to do all those other jobs.
duTch modified his like an A65 to be able to get to the sprocket. I think orabanda modified for a proper seal for the mainshaft.
Cheers

[denis]

Thanks Muskrat, 
Little screws it will be then.
The engine is still in the frame and as said, sprocket seems in a good nick, so the sprocket ‘ll stay in for now.
I’d be curious to see duTch and Orabanda’ s mods though.
I did your mod’ on the primary adjuster yesterday with the white chopping board, (as she agreed)
Thanks for the tip, the grooves were impressive!   I’m surprised how easily you can drill that stuff vs how fast the primary chain will slide on it.  Time and Kms will tell. 
Cheers, 
Denis

[morris]

Hi Denis,
When I had to change the oil seal on the plunger I drilled out the rivets and replaced them with 5BA screws.
As the inner cover is to thin to hold the screws I made up a steel ring, drilled and tapped to hold the screws.
Details about this and some more ideas/suggestions in this thread;
https://www.a7a10.net/forum/index.php?topic=4282.msg62295#msg62295

Getting the sprocket off means removing the gearbox and to remove the gearbox from a plunger it's engine out I'm afraid...

[Greybeard]

I used small nuts and nylock nuts to hold my seal in place. I found that the nuts touched the gearbox sprocket so I ground some metal off the heads and turned the bolts around. Just check clearance of sprocket plus chain before you put the engine back in the frame.

[denis]

Hello,
Tanks all for your input, I love these sprocket mod’s! 
I’ll first try to tap the inner case and red loctite (4 mm thick should be enough for making a thread, or not?) or use rivets as Trev said in another topic, and do the sprocket mod’ next time the whole lump comes off the frame. 
Thanks again, Denis

[Greybeard]

I wondered about using sealed Pop rivets:
https://www.rivetsonline.com/blind-rivets/closed-end-blind-rivets#1

[duTch]

 

.......duTch modified his like an A65 to be able to get to the sprocket. I think orabanda modified for a proper seal for the mainshaft.  .........

 Yep-  guilty as charged  there should be some pics on here somewhere-maybe a search will dig it up, the originals are buried in a Hadrondrive or two somewhere...

[Swarfcut]

As standard, the three rivets hold the oil flinger, (the bit you can see), and a further washer behind the chaincase to support the oilseal. As detailed above, morris made a rather clever thicker version of this washer, drilled and tapped to hold  three fixings bolts.

Just screwing into the aluminium chaincase  will not secure this thin original washer, so to do it with nuts, bolts and Loctite is possible but difficult because of limited access. Pop rivets will do, but may not survive long in the vibrating environment and ensuring they clamp the washer presents a challenge. Doing the job properly is an engine and box out exercise.

Swarfy.

[AdrianJ]

I've done this and the bike is nearing road testing. It remains to be seen how well my 5BA screws, nuts and loctite stand up to the vibration. Wish I'd thought of Morris's ring washer idea. That will happen if the engine has to come out again.
Adrian

[denis]

Hi all,
Ok, so finally got some time to get back to my bike and took the whole thing out to find what a groovy motorcycle I had, ha.
Good day all,
Denis

[duTch]

  yick ....It can't be very thick at the thinnest point......    

[denis]

At the groove made by the chain i’ve no idea. 
Concerning the oil seal, i’ve 2 or 3 mm left, so not thick enough for a proper oil seal, you guys reckon thick leather or felt would work squashed between the oil flinger and a home made ring? 
I can see the oil seal being there for the dirt not to come in rather than for the oil not to come out, right?
If so felt or leather should work.
Any advice welcome, i’ll have some more shed time tonight yeepee.
Cheers, Denis