Topic: Leak from tacho drive in cyl. head.HELP

[stevej]

My 550 K3 started leaking oil from the tacho drive area during an 80 mile round trip to Donnington park for the classic bike show earlier this year ,this oil was "black"and shorted no.3 spark plug.I changed the small o ring just inside tacho drive  for a new Honda part from D.S.Spares although the part no. was different to that in my parts book?and gave the bike a oil/filter change ,seal  seemed to fit ok,tonight I had my first run since fitting the new seal only to find  I still have a leak only now the  leaking oil is Rusty Brown!Any ideas please.Stevej

[ProTeal55]

My 750 is doing the same leak of rusty-brown goo from the tach plug.
I should fix it, but it isnt at the top of my list at the momment...

[phylo101]

Hi. Never had a 550 do this, but my 750 dribbles from the tacho mount in the head. I renewed the seal and no change, so tried a smear of RTV round the cable end.

All went well for about 60 miles, then I noticed the tacho wwas filling up with oil! So why wasnt there a nice split in the cable housing of a 25yr old bike when I needed one lol

phylo

[jdpas29]

make sure that the little crack that goes around the outside edge of the hole is clean and clear.  it is a real pain in the rear to get all the old rubber out especially if it has overheated and baked on.   once you know that crack is clear, clean the surface as best you can to insure a good seal.  push the new seal in (the side with the lip goes in first) and make sure you feel a little snap all the way around so that it's properly seated. 

if it weeps a little bit after this procedure, i wouldn't worry about it.  if it pours out and runs across the front of your fins and dribbles off... worry about it.

[stevej]

Oh dear,panic over! the rusty brown oil im seeing is from the tacho cable I greased/oiled ,obviously it gets warm spinning and runs out the base hense gooey mess on tacho cover but im glad I posted my message unaware as i was  that the little o ring needed to click into position it does now so will proberably last longer than the last one did, my thanks to jdpas29 for that info.

[bryanj]

Now you got me confussed as there are two seals!

One is an "O" ring that goes on the outside of the alloy casing that the cable goes into (held to the rocker cover by a screw)

The other is a proper seal that goes inside the alloy casing to seal the shaft of the drive gear--Dont brake that they are obsoleted

[stevej]

bryanj The only seal ive replaced is the "polo mint"shaped one that sits just inside the tacho drive cover,after a cleanup inside the housing it just  slots in perfectly now.I have seen another seal sitting on the tacho drive shaft I may well find this was the culprit all along but proberably wont know for sure untill I next go on a long ride,the brown oily goo i was seeing was the grease/oil I put on the tacho cable heating up and running out over the drive cover.