ET: Engine (Twin) 1954 Black Shadow Oil Fouling on front Cylinder only, any checks?

JohnA

Forum User
VOC Member
Been through all carb settings and had it to pieces many times, I feel like I can rule that out as well as plugs. New needle/jets/float - complete rebuild.

I have reversed the ignition leads to count that out. I did a compression test to find both cylinders equal. 52lb on kick.

I'm now convinced it's oil fouling, in the picture you can see the plug looks like it's painted satin and it's wet always. I have the same plug reading no matter what I do to the carburation and I've made many adjustments. I have six plugs that look the same. Again the rear is always perfect.

I have checked for wet sumping I was thinking maybe after the lead free conversion done some time ago, someone may have used valve seal and one popped off? Or a retaining screw come loose?

If any one has any suggestions before I get seriously spannering I'll take anything before I have to take down the head!
 

Attachments

  • 60510739_2193418120741177_2599305926842253312_o.jpg
    60510739_2193418120741177_2599305926842253312_o.jpg
    64.1 KB · Views: 20

mercurycrest

Well Known and Active Forum User
VOC Member
Looks like it's running too cold. If the ignition, rings and guides are all OK from your tests it can only be a restriction in air intake... Remember that wipe cloth you lost last winter? ;)
 

JohnA

Forum User
VOC Member
Haha, I am going to take off the tank and have a close look, but this is how it was delivered from a very reputable man :) I am going to inspect for a blocked oil line between the rockers,
 

JohnA

Forum User
VOC Member
Besides the slide height adjuster being on the other side can I just change carb bodies and keep float bowls?
 

chankly bore

Well Known and Active Forum User
Non-VOC Member
An uncommon cause can be pooling of oil around the lower exhaust guide. This can be exacerbated by the machine being stood on the left-hand propstand for a time. I've also had a head where rocker tunnel re-bushing broke through the exhaust port.
 

JohnA

Forum User
VOC Member
I have done over 200 test miles so far and a number of plugs, I think I can see some oil around the intake valve where I left it closed. Manifold is a little tricky to get off so I am going to order an inspection cam which Ive wanted for years.
 

Bob

Active Forum User
Non-VOC Member
John, I had the same problem and I agree it's oil fouling. The front plug on my Rapide would foul after a few miles. I tried hotter plugs and they would go a few more miles before fouling.
I cured this by fitting new valve guides, the ones from VOC spares with the oil seals, and have had no problems since.
 

JohnA

Forum User
VOC Member
John, I had the same problem and I agree it's oil fouling. The front plug on my Rapide would foul after a few miles. I tried hotter plugs and they would go a few more miles before fouling.
I cured this by fitting new valve guides, the ones from VOC spares with the oil seals, and have had no problems since.
I may still be wrong but I think this is where I am headed, I do only get smoke when I kick it hot as in when it has stalled. Kicking cold just clears the oil with the tickle and turning the motor I think. Some one has modified the rocker feed bolts - Im wondering if they also have a used seals which have gone faulty, the bike was unused for a long time.
 

Attachments

  • 60906264_2201917789891210_5798955613450928128_o.jpg
    60906264_2201917789891210_5798955613450928128_o.jpg
    249.8 KB · Views: 23
Top