Finally rebuilt my Dad’s Comet from the ground up. Did a couple of rides round the block, then a 25 mile, followed by 75 miles and yesterday 170 miles. All at running in speeds and nut bolt checks between each ride.
After the first rides except for a spot of oil on the ground from the gearbox output shaft everything is oil tight and the bike feels really good.
On returning from the 75 mile ride I checked the oil which had not seemed to have gone down and in anticipation of a longer ride topped it up. Arriving home from the 170 miles there is some oil on the front of the back mudguard and left side of the swing arm although it must not be much as the oil level looks the same as when I set off. Tracing the oil up there was a drip from the UFM return pipe (bolt is tight and sealed) and some oil against the throttle cable where it sits against the UFM.
Removing the tank showed a trace of oil coming from the filler area all heading to the left side of the bike. It’s hard to see if it has come from under the cap or the weld - the paint seems intact around the weld.
The oil level in is about 1/2” below the base of the filler pipe (I couldn’t see a cross brace when filling initially). The cork seal in the cap is rock hard.
Is it possible that the returning oil is reaching up to the cap and leaking past the cork seal although I don’t think this was this happened on the earlier rides. There was a little oil on the left side of the RFM after these rides but up put this down to the weep from the gearbox output shaft, maybe it wasn’t.
50% of the ride was very bumpy. Could it be possible for the oil to splash up an under the hard seal? This is my favourite but asking here just incase I'm missing something.
This was defiantly not sump oil coming up and overfilling the UFM - did that when I first got the Vin from Dad years ago.
Any suggestions please
After the first rides except for a spot of oil on the ground from the gearbox output shaft everything is oil tight and the bike feels really good.
On returning from the 75 mile ride I checked the oil which had not seemed to have gone down and in anticipation of a longer ride topped it up. Arriving home from the 170 miles there is some oil on the front of the back mudguard and left side of the swing arm although it must not be much as the oil level looks the same as when I set off. Tracing the oil up there was a drip from the UFM return pipe (bolt is tight and sealed) and some oil against the throttle cable where it sits against the UFM.
Removing the tank showed a trace of oil coming from the filler area all heading to the left side of the bike. It’s hard to see if it has come from under the cap or the weld - the paint seems intact around the weld.
The oil level in is about 1/2” below the base of the filler pipe (I couldn’t see a cross brace when filling initially). The cork seal in the cap is rock hard.
Is it possible that the returning oil is reaching up to the cap and leaking past the cork seal although I don’t think this was this happened on the earlier rides. There was a little oil on the left side of the RFM after these rides but up put this down to the weep from the gearbox output shaft, maybe it wasn’t.
50% of the ride was very bumpy. Could it be possible for the oil to splash up an under the hard seal? This is my favourite but asking here just incase I'm missing something.
This was defiantly not sump oil coming up and overfilling the UFM - did that when I first got the Vin from Dad years ago.
Any suggestions please
