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Blown a Seal?

Posted: 05 Nov 2017 20:43
by Butch
Finally got the Camel back up on the table today. Scratching my head over the oil leakage on the last ride out (see previous post - Oil Thread).

Really couldn't see any likely area where it had been distributing from. Top of the motor all being dry, even around the back. Gummy underneath. Difficult to see a level on the dip stick, but a pipe cleaner poked down there seemed to suggest it was overfilled - ????? Figured I'd drop the oil and measure it out.

At point of pulling the sump plug I had it pissing out and piss thin. And a very strong smell of gasoline. Problem likely understood at least then. Taps have been off. Pulled the pipes and checked the tap action by blowing up some separate hose plugged on. Taps work in the directions I figured. Hmmmm.

So. 6/8 miles with some very thin oil. Have I damaged the bottom end? Is a major seal irretrievably blown? I'll need to buy and fill with fresh oil and see how it goes I 'spose.

Re: Blown a Seal?

Posted: 06 Nov 2017 11:33
by MickeyMoto
Hi Butch,

If you have petrol in the oil, would this be a carburettor fault? Check the needle valves? I would think that you would fill the cylinder and it would lock up, though. Maybe you have ring / bore problems? Have you traced the oil on the rear? It may be from the breather. Do you have the baffles in the pipe?

Mike.

Re: Blown a Seal?

Posted: 06 Nov 2017 17:01
by huub
i've had the same happen to a 350 , i left the taps open , and the tank emptied itself into the sump.
due to the angle of the carbs the petrol can run into the cylinder head , instead of leaking out.
mine wouldnt start ( crankcase filled to the brim) so no harm done...

Re: Blown a Seal?

Posted: 07 Nov 2017 09:07
by Butch
Well yes, that is pretty much my thinking.

In the first place the fuel has to get past the pet-cocks. I’ve either left them open or they leak.
And regardless, you’d then expect the carb float and needle to hold back the flood.
Accepting all of that the fuel then has to decant down the inlet track and through the port.
You’ve either got a valve that would fail on a leak down test, or by chance it is open.

I’ve heard of these things happening to others and been rather sceptical.

I was back working on the bike last night. Rechecked the pet-cocks. They seem OK.
Pulled the bottoms off the carbs and checked the float/needle action. They seem OK.
Dropped the sump plug again and a little more pissy oil came out.

Refilled the sump with fresh oil. Bike fired up first kick. Sounded no worse than it ever did.
I’ll run it out later in the week and see if oil is still going to get by seal somewhere.

The bike has been leaning a long way over on the side stand which I suppose could affect float heights.
Other than that I’m at a bit of a loss.

Sorry - Baffles in what pipe?

Re: Blown a Seal?

Posted: 07 Nov 2017 10:59
by MickeyMoto
The crankcase breather pipe has baffles in it, I presume to give some back pressure. Later models had a collector box with no baffles, earlier models vented out the back, in one case all over my disc!

Re: Blown a Seal?

Posted: 08 Nov 2017 09:53
by Butch
My bike is either a weird cross over model or a bitza. Twin shock at the back, and a drum; single disc up front.

The bike carries a slim breather box at back of the cylinders. Rocker covers vent into it plus some other pipes. All looks quite a neat arrangement really.

Re: Blown a Seal?

Posted: 08 Nov 2017 17:57
by 'It must be a .....'
Hi Butch, the basis of your Camel appears to be a late twin shock 500; having the box section swinging arm along with a disc front brake.

Re: Blown a Seal?

Posted: 10 Nov 2017 10:12
by Butch
I think it might be OK. Not going to be trusting that fueling system for a whiles though.

Think I'm going to be shimming the clutch again. Too abrupt now. Grrrr. Must be the cold weather or the thicker gloves.