T90 Oil Leak

Tappet blocks rarely leak although oil can leak from the bolt that holds it in the barrel, normally its the top or bottom pushrod seal that leaks. Thoroughly clean the area and ride the bike but keep stopping to have a look and you should be able to tell

 

The pushrod tube seal will likely be the culprit, there are uprated seals available and I would go for a set of those.

 

Hi Fuseman, this was true when machines originally came out of the factory, this was due to a combination of things, mostly worn out tooling that caused poor mating surfaces and inconsistent tolerances, leading to oil leaks amongst other faults, however modern gaskets and seals are usually high quality and when used usually eliminate leaks, also a lot of people now use quality silicone to seal chain cases, however this needs to be applied very sparingly, a carefully re built engine will be completely free of oil leaks, what is top quality is the alloy that was used in the engines, often these "battle scars as I call them" can be carefully filed out and finished by various grades of wet and dry paper, then buffed up so they are like new, personally any restoration I complete I like to leave these in place as they all tell a story. Ride safe all from an ageing Rocker.

 

The places oil can leak from are a chain oiler from the oil tank if its fitted, can be turned off with the screw inside the oil tank. A split in the engine breather to oil tank pipe, unlikely. The oil seal in the primary on the output shaft, these would be for engine oil and the mainshaft to output sprocket oil seal in the gearbox, gearbox oil. None of these are urgent if you don't mide dripping oil.

 

if its pushrod seals, i generally use clear silicone seal.

clean it thoroughly all arond and then use probes and paper strips to wind a bead around th eseal junction.

dont use orange silicone or everybody will know that you are a peasant like me.

it can last a surprisingly long time

eventually you will re-do the seals, but you dont have to be in a hurry

 

I have a 66 500 and had a similar leak that was cured with a new pushrod seal.