Leaking Head Gasket? & Mikunis suck

Status
Not open for further replies.
G

geoff71

Joined
Jan 6, 2010
Messages
27
Country flag
I will make a long story short - Riding into work, one Mikuni sticks w.o. Who would have thought that, I thought Mikuni's were the standard to which everyone aspires to? At least when my Amals stick I can get them to unstick... :P

Anyway, I have oil leaks. Being new to Norton and used to a Triumph, I merely have shrugged my shoulders and let it mark its territory. However, I am getting worried by the amount that is staining the barrels - I am not sure if its coming from the rockers, inlet cover gaskets, the original rocker feed hose, or the head gasket. Does anyone have a quick method for knowing if the head gasket is leaking w/o pulling the head?

Thanks,
Geoff
 
Eliminating all other possibilities is the best way of not pulling the head. I have pulled the head only to unresolved the issue that was due to old, hard oil feed lines.
The leak from these lines seldom show themselves while idling in the drive. It will eventually end up as a hot spray on the leg while crusing the interstate. It is usually a split or crack close to the nipple. Idle it up and bring up the pressure and move line from one side then the other to reveal the leak.

Valve cover gaskets are easy enough and the origin of a leak is quite evident.

Torque the head to see if you have a loose fastener. This should be done periodically.
 
pvisseriii said:
Eliminating all other possibilities is the best way of not pulling the head. I have pulled the head only to unresolved the issue that was due to old, hard oil feed lines.
The leak from these lines seldom show themselves while idling in the drive. It will eventually end up as a hot spray on the leg while crusing the interstate. It is usually a split or crack close to the nipple. Idle it up and bring up the pressure and move line from one side then the other to reveal the leak.

Valve cover gaskets are easy enough and the origin of a leak is quite evident.

Torque the head to see if you have a loose fastener. This should be done periodically.
Click to expand...

And you forgot your favorite fix for leaks... reed valve breather!
 
Mikuni's stick if they just have the standard springs and the slide gets dirty, Double spring it to be safe. (an Amal spring fits inside the stock Mikuni) Could be a side effect of ethanol fuel dissolving stuff!!

Oil leaks, pull the head as a last resort unless you are sure its the head!! Most oil leaks are cured by the fitting of a PCV valve (unless there's an actual problem)

Don't get depressed, fix it and smile!!
 
You'll sort it out Geoff, just the same not much fun at the time.
Let me know if you want to part with the Miks.
AC.
 
Same problem here. Seemed fine when idling. I finally got it on the road and had oil everywhere.
Anyway, I just today recieved the sweet stainless Rocker feed lines from Old Brits. We'll see if
that takes care of things tomorrow. :wink:
 
"Don't get depressed, fix it and smile!!"

In my book I can't be depressed with a British bike, its more of a feeling of delayed gratification...

Thanks for the tips, I have the gaskets and was going to try to hold out on the rocker feed line - I guess that just got bumped to the top of the list. Too bad my Triumph isn't off the lift yet, at least I would have something to ride.

As far as the Mikunis - as long as the Caswell isn't melting inside the tank (its steel), its the springs. I am going to try to put a set of resurrected Amals back on - the Mikunis just seem to complicated.

Thanks again!
 
geoff71 said:
As far as the Mikunis - as long as the Caswell isn't melting inside the tank (its steel), its the springs. I am going to try to put a set of resurrected Amals back on - the Mikunis just seem to complicated.

Thanks again!
Click to expand...

As you may be aware fiddling the Mikuni slides can be a little frustrating. The needle can very easily be bent. I had this issue where one side would stick a little but not WOT. Not until I saw the needle rolling off the bench did I notice a wobble. Straightened it out (a delicate operation) and all was well.
Just something else for you to check.
 
If you're having trouble pinning down the location of the leak talcum powder's pretty good. Wash the top end down, let it dry off and dust it down with talcum powder, run the engine for a bit and the oil should be easy to spot.
 
Head oil leaks seem to migrate anywhere and everywhere, even in front of where they originate. The head is hot so the oil thins and sometimes you can't even see where it is coming from. Another culprit is the stacked oval covers over the rocker shafts. Usually it likes to come out the exhaust rocker covers. The rocker cover gasket can be trimmed along the inside bottom so the oil doesn't pool there.

I used to run Mikunis in the 80s and had them stick on me at first. The Amal spring inside the Mikuni spring cures this. No need to abandon it altogether just for this reason though. I did switch back but it was only because it was faster with the Amals, and well, they look like they belong there.
 
The Mikuni's are easier than the AMALs trust me!!! Just get the spring off one of the old amals and fit it along with the Mikuni spring, problem solved!!
 
Don't say that Gino, I wanted to buy them.
I think Geoff has two, Twin slide springs ? on Twin carbs, will that be a bit hard on the wrist after a while.
Yes they can be complicated, after Amals. :wink:
 
Status
Not open for further replies.

Similar threads

Mart UK
  • Locked
Head Gasket, Breather, Both / Neither?
2
Replies
21
Views
1,832
Lineslinger
Lineslinger
J
  • Locked
Leaking head gasket 850 mk3
Replies
10
Views
2,629
Deets55
Deets55
comnoz
  • Locked
Oil leak at the head gasket
2 3 4 5
Replies
89
Views
10,487
lcrken
lcrken
Back
Top