Darmah SD sport identification

I have not posted for a while since getting advice on buying. I did end up buying a 78 Darmah and if was not for Corona would be out regularly on it.
Posting this time to see if anyone can tell me more about the briefly sold 78-79ish Darmah SD sport. Not the SD ss.
As I understand it for English market came with conti,s and 40mm carbs but with some issues as may have kept 32 cm intakes!!
Does anyone know if discs were drilled and how to tell if a Darmah was originally sold as sport.
Also what is expected BHP for a good one. Spec sheets indicate 65 but at least 3 period road tests with dyno say 52 to 54 bhp.
Thanks Peter

A lot of information out there, great bike, getting rare to find now.

I think that 52-54 bhp is nearer the correct figure.
The Darmah’s fitted with 40mm carbs as standard even with full 40mm intake stubs, had a 1 into 2 throttle cable that would only open them to around 36mm and the exhaust headers were double skinned with a smaller ID than the pipes fitted to the PUKKA SS’s.
This goes for all the standard Darmah’s inc’ the full SS model.
To get the carbs to open fully you need to fit a twin pull throttle and 2 separate cables like the genuine SS’s.

Steve R

Thanks very helpful info. I am still trying to pull together books and info on the Darmah. My 78 came with lots of history and Bill’s for older engine rebuild including head mild gas flowing etc. 40MM carbs contis etc. Had some issues with sticky rings on rear think due to layup. Currently making 60hp on dyno but had to have a new clutch fitted to get that.
Rearly not sure what size intake stubs are. How can I tell. Receipts don’t list intakes. Also any suggestions for history and spec by engine number reference books.

60 rwbhp is pretty healthy, the claimed 67 would have been at the crank.
It’s 99.9% certain that if you’ve got 40mm carbs you’ll have 40mm stubs to match them and the gasflow.
Apart from the bigger ID the difference between the 32mm and 40mm stubs is the width between the studs that bolt them on. I’ve just dug out a spare 40mm stub and the stud centres are as near as damn it to 58mm.
Standard clutches would both slip and drag when hot, this showed up as trouble finding neutral and when the motor hit peak torque/came on cam the revs would soar until the torque peak was past then it would drive again.
Surflex made an upgrade pack of friction and steel driven plates for them back in the day to overcome this problem.
Others fitted the clutch springs from a 450cc single, but these made an already heavy lever action even worse.
I tried several different ways to combat this problem before solving it perfectly and then after all that effort I found a dry clutch conversion at the WDW2000.
Are you a DOCGB member? if so contact Kev Baker the mem’ sec’ and get him to give you my home phone number and I’ll talk you through your options.
I converted my clutch operation to Hydraulic back in the early 80’s and to this day it’s the lightest Bevel twin clutch I’ve ever tried.

Steve R …not the northern imposter.