General mixture 750 FIRE engine.

[tashman]

Every time I remove the spark-plugs on my 1992 750 fire engine they're covered in white deposits.

I believe this means that the engine is running too lean.

The engine runs badly untill it is fully warmed up.

Looking at the emissions test from the last 2 MOT's the CO reading has been in the region of 0.1%-0.2% CO.
I believe the recommended setting is 1.5% CO? Can someone confirm this?
I have connected a gas tester to the exhaust pipe and tried turning the mixture screw a couple of turns but there was almost no change in the CO reading.
Is there something else I should be doing to adjust the mixture?
Am I right in thinking that anti-clockwise makes it richer?
Many thanks and any ideas would be appreciated.

 

[oldernowiser]

Looking at the emissions test from the last 2 MOT's the CO reading has been in the region of 0.1%-0.2% CO.
I believe the recommended setting is 1.5% CO? Can someone confirm this?

The test figures are too low for a carbed Panda - you (almost certainly) have an air leak.

A good/tame tester would have advised about the figures being wrong.

Check the vacuum advance unit, and it's pipework, first.

 

[tashman]

the vacuum pipe is fine and the advance works correctly
At the moment i'm cleaning the white stuff off the plugs every 1000 miles.

 

[Alan.D]

The mixture screw is prone to rounding off by being tightened then released flattening the point on the screw which makes it completely usless. You either need a new mixture screw or a different carb...

 

[Chas Uno]

Don't forget that the mixture screw on the Weber 32 TLF carburettor ONLY adjusts the mixture strength at tickover. It does NOT affect the mixture at wide throttle openings. The only way to richen the open throttle mixture on this carburettor is to fit a bigger main jet.

White deposits on the spark plugs can also mean that the timing is too far advanced, or even that the spark plugs are too hot a grade for the engine. Oldernowiser is also on the right track by suggesting that your induction side has an air leak.

 

[JimMagill]

The engine runs badly until it is fully warmed up...

They all do that... Hence why mine is called splutter, lol!

(thou I still think you've got a problem but don't expect it totally disappear)

Jim

 

[Nuova500]

mine runs beautifully when cold mind you its a proper engine

 

[JimMagill]

mine runs beautifully when cold mind you its a proper engine

Sorry, I should of said... All the 750's are a pain when they're cold. Even the guy raping my wallet today when I was buying splutter back at 15 pounds for every one of his BHP today told me 'Ah, you'll need to leave him till he's wamed up'

Jim

 

[Alan.D]

Jim the Italia 90 runs just as well when cold as hot?