Britbike forum Forums British Motorcycle specific Brands Triumph bulletin board 9989 screw threads

Hello; any of you with a 9989 camshaft (Harris made) on the bench can tell me if the hole threads in the TS are UNF or BSF?

Thanks

Thank you mate.

20 tpi, same as bsc? I know that the earlier nut fits, as does the factory assembly tool.

Hi TinkererToo; the hole is for 1/4 so if it is UNF should be 28tpi. Seems that you are talking about the external thread.

Sorry, I was, can you get a 1/4 UNF tap in Uruguay?

Hi; I dismantled there to be sure what I did in the past and found the screw a bit loose but UNF. I tested a BSF but did not worked. Would be very very frustrating tear up the cases to fix that but seems that I did the testing when I built that.
Yes; there are UNF taps here.

Just run a tap up the hole, it goes no-where else, so no need to dismantle!

I removed the magneto to check that but I do not think that an UNF tap into a BSF thread can make for a good tight hold for the taper of the magneto to the camshaft; anyway was UNF and had the UNF bolt there so was all good.