Just bought a ‘73 Sherpa 350 model 92.  Changing fluids and can’t figure out how to drain clutch fluid...need help.

The drain plug underneath the left side case in line with the Bul part of bultaco that is cast into the case. That is assuming it has the original case and not the later model case in which case the drain is actually one of the case mounting bolts- the middle one on the bottom and it has a much larger round head.

 

If you like you could leave well alone drain plug wise and remove the clutch adjusting access plate (plastic) and lay the bike on its right side and the oil will come out from there pretty quickly. Turning the bars will allow more lean. Are you draining gearbox?

I removed two of the screws on the bottom of the clutch primary case and they were not drain screws.  There is a screw on the bottom of the left side case, underneath...is that what you are referring to...it’s about the size of a nickel and has a flat blade screwdriver slit in the head?

Here is what I can’t figure out what it is...the plug with the flat blade screwdriver head.

Your clutch case should look like this, you can see the plug underneath

https://www.ebay.co.uk/itm/Bultaco-Lobito-Pursang-Alpina-175-clutch-engine-case-cover-cap/172934687132?epid=7007483100&hash=item2843b5e99c:g:19UAAOSwnw9Z5~gd

 

In your photo the original gearbox drain plug is the one behind the one you are pointing to, although I can't see that it has a drain bolt in it. The one you are pointing to is something that someone has added, maybe made their own gearbox drain if the original is damaged. I can't tell where exactly it's positioned but could also be a drain for the ignition should water get in there

 

The casting on the other side is for a speedo drive which is a hangover from older engines. Thyey weren't used on later bikes, It's blank and isn't drilled

I think Sherpa325 meant to say RIGHT  side case.........

Thanks guys.  The reason I couldn't find the primary drain plug is because it was apparently sheared off in this bike's past life.  The hole had been filled with what looks like epoxy.  I wound up using my brake bleeder vacuum pump to suck the fluid from the primary.  Not really happy to find a patched hole in the primary.

5 minutes ago, TigerGA said:

Thanks guys.  The reason I couldn't find the primary drain plug is because it was apparently sheared off in this bike's past life.  The hole had been filled with what looks like epoxy.  I wound up using my brake bleeder vacuum pump to suck the fluid from the primary.  Not really happy to find a patched hole in the primary.

Replacement primary drive covers are readily available

1 hour ago, feetupfun said:

Replacement primary drive covers are readily available

I’ve had my Sherpa for about 3 weeks...never had a trials bike before.  Where is a good source to find a primary cover (also, is there a place I could find a part number...I imagine that primary cover was used for multiple models?).  Would also like to find a clyinder...I’ve got some broken fins on mine.

Edited April 23, 20188 yr by TigerGA

US ebay usually has lots of those primary drive covers advertised. The original cover on a M92 is the most commonly available type of cover and sometimes called the boot heel shape.

A good M92 cylinder will be much harder to find because it is a wearing part and unique to only a few models

This is the first boot heel primary drive cover I saw when I searched on US eBay https://www.ebay.com.au/itm/BULTACO-RIGHT-SIDE-COVER-FROM-1971-ALPINA-125-DIRT-BIKE-TRIALS-BIKE-ENDURO/123068514902?hash=item1ca7748256:g:HNcAAOSwuIRamwb I'm sure there will be lots more listings

 

The M 92 barrels are used on the M92, M125 and the M151. I have a 151 engine and the barrel still has 92 stamped on the top of it. I would also say the Alpinas from that era might have the same barrel as well. I`m not sure on that one though. Graham.

15 hours ago, bullylover said:

The M 92 barrels are used on the M92, M125 and the M151. I have a 151 engine and the barrel still has 92 stamped on the top of it. I would also say the Alpinas from that era might have the same barrel as well. I`m not sure on that one though. Graham.

Only the M99 (325cc) Alpina model barrel is the same as the M92. After the M99 model Alpina, the stroke was made longer to make them 350cc, so the later Alpina "350" barrels are also longer, so are not the same as the (325cc) M92 barrel