Slow then sudden increase in fuel consumption

[kinger]

Wheels spin freely? No bearing/brake drag?

[Oakie]

Could be time for a new set of plugs

Checked during service in Feb 4000km ago although they are now 20000km old

Wheels spin freely? No bearing/brake drag?

Seem to be OK but probably worth checking again this morning.

[Drew]

Valve clearances would be high on the list of things to check. If it's an American model, I wonder if the catalytic converter isn't clogged up a bit.

[Oakie]

There will be a little plug in the end of a rubber hose under the bike. Pull it out and see what comes out.

May pay to put a jar there.

Did that and thanks for suggesting the jar! Got half a cup of water with a bit of oil in it. Came out looking about the colour of a weak cup of tea. You reckon half a cup would be enough to upset things?

Valve clearances would be high on the list of things to check. If it's an American model, I wonder if the catalytic converter isn't clogged up a bit.

Have thought about valve clearances. Done just on 20000k ago so they should still be OK? UK model so no catalytic converter.

[T.W.R]

Checked during service in Feb 4000km ago although they are now 20000km old

Can start to die unexpectedly though.

You've got a few options to look at like mentioned in other posts, but 12 simple checks are:

1) Drivers erroneous operation (Very doubtful)
2) Slipping clutch (You'd know)
3) Dragging brake
4) Insufficient tyre pressure (Doubtful)
5) Decreased compression pressure
6) Fuel leakage (you'd see it)
7) Maladjusted idling speed
8) Contaminated air cleaner
9) Maladjusted carburettor
10) Clogged muffler (Doubtful)
11) Poor spark
12) Maladjusted ignition timing

So you've got a few options to check, you said you'd had the brakes done so in reality that'd lessen over time not increase if they were dragging.
Valves you'd hear them if they were that far out of adjustment to cause that much change in consumption & it'd effect performance too.

[mossy1200]

Did that and thanks for suggesting the jar! Got half a cup of water with a bit of oil in it. Came out looking about the colour of a weak cup of tea. You reckon half a cup would be enough to upset things?



Have thought about valve clearances. Done just on 20000k ago so they should still be OK? UK model so no catalytic converter.

I think you need drop match into jar to confirm if its water or petrol.

[Oakie]

Can start to die unexpectedly though.

You've got a few options to look at like mentioned in other posts, but 12 simple checks are:

1) Drivers erroneous operation (Very doubtful)
2) Slipping clutch (You'd know)
3) Dragging brake
4) Insufficient tyre pressure (Doubtful)
5) Decreased compression pressure
6) Fuel leakage (you'd see it)
7) Maladjusted idling speed
8) Contaminated air cleaner
9) Maladjusted carburettor
10) Clogged muffler (Doubtful)
11) Poor spark
12) Maladjusted ignition timing

So you've got a few options to check, you said you'd had the brakes done so in reality that'd lessen over time not increase if they were dragging.
Valves you'd hear them if they were that far out of adjustment to cause that much change in consumption & it'd effect performance too.

Thanks for that. I can understand the maladjusted stuff but with no loss in performance it's just got me baffled.

I think you need drop match into jar to confirm if its water or petrol.

Oh believe me ... there was a large part of me that wanted to do that.

[Oakie]

Clogged up air filter is the spanner-man's assumption. Two years riding on Christchurch's dusty roasd on what is apparently quit a small filter element. Also recommended replacing the plugs as running with the clogged up filter won't have done them any good. By this time next week I guess I'll know.