More thoughts...
1. What diaphragm is it?
Blue? Orange? Grey? Double Grey?
I wouldn't go stronger than an orange one on a road car.

2. There have been coating adhesion problems with some recent ACL thrust washers in packaging marked 'packed in Tasmania. These are a product of China. Contact Graham Russell for further info.
Previous ACL ones said Made in Tasmania.

Edit
What crank? 998 & 1098 have smaller thrusts than 1275s so more psi load when clutch is disengaged.

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

These are the thrust washers I fitted. It’s for an 1100. I guessing they may be the problem then after all.
Also pulled clutch out this afternoon. It’s a blue dot but also worked out that the diaphragm doesn’t sit flat either. Need to take 28 thou off of posts to get it flat. Current thickness of clutch plate is 7.76mm so almost new still.

_________________
A recent study found the average Aussie walks about 900 miles a year
Another study found Aussies drink, on average, 22 gallons of alcohol a year
That means, on average, Australians get about 41 miles per gallon

Kind of makes you proud to be an AUSSIE

The last 2 1330 motors I helped build we sourced other thrusts.

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Can I ask where from and what brand please?
Pete

_________________
A recent study found the average Aussie walks about 900 miles a year
Another study found Aussies drink, on average, 22 gallons of alcohol a year
That means, on average, Australians get about 41 miles per gallon

Kind of makes you proud to be an AUSSIE

Will advise when the owner finds records.
I think were GLYCO brand .

Try here https://www.precisionintl.com/products/ebt2204t2gy

Edit check, I think these were for 1098 with 2" mains eg sprite.
Same size as 1275 not yours.

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Had a talk with Graham Russell today about this issue. He was explaining that the thrust washers that are made in china are a bright bronze colour instead of the dark dull colour of the originals. Also the china one have square ends instead of the rounded ones. We ascertained that i have in fact got the chinese but as it's not a performance build it should be fine to keep them in. Graham has has success with in road motors but has had dramas in race motors. He also stated it is normal for the revs to drop a small amount on small bore motors with a heavyish clutch and also said the new Blue Dot diaphragms are actually stronger than the old ones and not far off of the orange ones.

Anyway I sorted out the diaphragm on mine as it was not sitting flat. Had 30thou taken off of the posts, reassembled it and checked again. It's not perfect but within about 3 thou of being totally flat.
Put it back in and ran it up.
It is heaps better now, revs still drop but only by about 100 rpm. I'm happy with that so it will stay like that for now.
Thanks to all for your help especially drmini and Graham.
Sorry for the long winded response.
Pete

_________________
A recent study found the average Aussie walks about 900 miles a year
Another study found Aussies drink, on average, 22 gallons of alcohol a year
That means, on average, Australians get about 41 miles per gallon

Kind of makes you proud to be an AUSSIE

Hi all,
Bit of an update. We had to pull the engine and box out due to a different issue ( diff pin let go, may have seen my sons post on Facebook about it )
Anyway we checked the thrust washers and they were in the correct way but were about stuffed. Will find pictures later and post.
The engine only had about 500km on it and the thrust material had started to wear excessively. To the point that we had 6 thou end float when built and was out to 7 1/2 thou when we pulled it down.
Found a good set of old ones in the garage and fitted them.
The drop in revs has totally disappeared now, happy days.
These were new ACL thrusts but going by the information available they are the ones made in China. Different colour and no angle where the 2 halves meet.
Try and keep all your old ones as these new ones are crap.
Thanks for all the advice and if GR reads this thank you for your time on the phone.
Pete

_________________
A recent study found the average Aussie walks about 900 miles a year
Another study found Aussies drink, on average, 22 gallons of alcohol a year
That means, on average, Australians get about 41 miles per gallon

Kind of makes you proud to be an AUSSIE

They are supposed to be sintered bronze that's why originals are dark. They are quite hard. I suspect China isn't doing it properly, if at all.

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.