Carb to Carb tray gasket

[fredperrybruce]

Hi , I've been having trouble lately with loss of power and petrol coming out of exhaust. So today I decided to take out the Carb and take a look.
Here's what I found!

Does this look bad and what kind of affect would this have on the running of the scoot.

I believe the small black bung thing? come's from the bottom of the carb and was found in 4 bits.

I have also found lots of quite large particles of c**p under the fuel filter, "god know's how they got there" .

As a newbie this is all very new to me and all advice is much greatly received. PX 125 Disk 2005

I cant ad an attachment as my files are to big so take a look at this link

s1273.photobucket.com/user/fredperrybruce/media/WP_20130626_001_zps1ef80215.jpg.html?sort=3&o=0

[pxguru]

You are having some trouble but at least we know what your problem is now. Everything you have been saying in the last few posts tells me the clutch side oil seal leaking. Gearbox oil level, black gunk running from exhaust, severe loss of power, white spark plug. To minimise the internal damage and before something expensive breaks, dont start the engine again until this is fixed.
KRU has just fixed his own one of these you really need him to come to you now!

[fredperrybruce]

So are you saying the clutch side oil seal is more than likely damaged?? Is this a big job or can it be a done fairly easy?. I took the cylinder head of today and found a'lot of carbon around the top of the piston head and gasket didn't take the bottom part off as I was worried I might damage the piston or not fit it back in right!

[vespasian]

could be a knackered crack seal,however i would eliminate other possibilties first,is your carb set up right,have you recently changed it,put other jet sizes in? also is there gearbox oil coming out of the breather on the carb cover? is the compression low?are your rings worn,causing unburnt fuel,,if it is the crank seal,then yes,its a case of partial strip down of the engine,splitting the cases,removing clutch and crank and replacing the seal,if its a metal seal,there a pain in the arse to get in,i put one in last week,and had to heat the casing,would not go in on its own

[fredperrybruce]

Wow so many things it could be!

I'm replacing all gaskets in and around Carb and cylinder tomorrow, have already stripped and cleaned the carb ready to go back in. Will check more things out as I go, all a good learning process for me

[kru251]

Well, the house was put on the market Saturday 22nd June. Sold by Tuesday 25th!!!!
So if you want use of my workshop you'd better be quick!!!!!!!

[pxguru]

Jun 27, 2013 22:30:55 GMT fredperrybruce said:

Wow so many things it could be!

I'm replacing all gaskets in and around Carb and cylinder tomorrow, have already stripped and cleaned the carb ready to go back in. Will check more things out as I go, all a good learning process for me

There isn't so many things it could be! Its the oil seal. We have all had them fail occasionally and I always remember the one that came out 300 miles from home in the rain!

Have a read of this old post vespa.proboards.com/thread/3155/air-leak-test

This is the best way to tell and also that the new one is seated properly.

[bsr65]

from my experience servicing vespa's and coming across a lot of knackered clutch seals, if you drain the oil and it's full of petrol, that's a sure sign, or if hardly any oil come's out and you refill with fresh oil then black smoke belches out the exhaust that's another sure sign. Must be where the seal tears that you get either symptom.

[pxguru]

Yeah, the garage full of smoke test is a sure sign a seal is really gone! As I think his fredperrybruces one is.

On a fast scooter where speed is the only factor then the seals must be pretty good all the time. If your lucky, oils seals wear out slowly just like piston rings, tyres or brakes. They get to a point where you just have to change them but there is a lot of time in between where they might be not so good and slowing you down. As I have banged on about too often for some, a pressure test is the only way to tell what's what

[sbwnik]

A quick word of warning here:

There was a method of testing for blown oil seals which was popular in the 80s. Fire the engine up, put your foot over the exhaust and see if the engine dies. If it does, then the seals are fine (The engine is chocking on its own exhaust fumes). If not, the seal is blown.


It made sense, and most of us have tried it. The problem was that filling the crank case with burnt exhaust fumes built up a lot of pressure as the engine continued to burn fuel but fail to pump it out.... An this in itself would sometimes cause a seal to fail.

A good theory, but flawed.

[fredperrybruce]

Yes very true!! I already read this on another forum,good job to as I was gonna use this method to test for a leak. Lucky I found the thread Cheers anyway!

[kru251]

Reminds me of that old 'adage'.

If it isn't broken........................................fix it; until it is!!!!!!!

[fredperrybruce]

After another day of tinkering about with the scoot and then taking it for a good thrashing there seems to be no more leaks. There's a small amount of burnt fuel coming from end of exhaust but that's all. Scoot is running sweet got rid of the bogging in high revs buy adjusting the mixture screw and the plugs a nice brown slightly rich but ok. Few thank god that's over "until the next fault pop's up"

[kru251]

You can be sure that next fault is just waiting for the Gremlins to realise you've sorted this one. In the meantime.........................ENJOY IT !!!!!

[pxguru]

Who was it that said "youth was wasted on the young"? At least, check the gearbox oil level is ok before every ride!