NC30 using a lot of petrol!

[tazbert]

Hi Guys,

Thought I would try to pick your brains if I could!

My NC30 is using rather a lot of petrol at the moment.
Normally it will use (for example) 6 litres in 60 miles
(about 45 to the gallon if my maths is right).

It has been standing for a couple of months, and the last time
I took it out for a long run it used about 9 litres in
the same distance.

The only symptom was a slight 'wooliness', especially in
the midrange. No misfiring or roughness to indicate any
ignition problems.

I've checked the choke, that seems to be working ok,
do you have any suggestions for things to check when I
strip the carbs off?

Thanks

Andy

[wullvfr]

obviously it could be running rich!!!

any backfiring at all,does it bog down bad at all?what exhaust system are you running?

the best way to work out your mpg is making a note of how many miles you get before having to go into reserve.


wull

[tazbert]

no backfiring etc, it seems to run almost normally.
just needs a bit more throttle than usual in the midrange (accelerating on the motorway etc)

engine is standard, apart from an F1 jet kit (bought from here a few years ago) ;o)
and the intake opened up a little at the front of the frame (under the steering head).

hth

thanks

andy

[Cammo]

do you have any suggestions for things to check when I
strip the carbs off?

Yo Taz, best bet is that some of the holes in pilot jets, and main jets will be blocked. This will cause it to use more fuel as you'll need to use more throttle to make up for dodgy carb.

Open the carbs up and check all these, blowing them out to make sure they're not blocked. Fuel residue will block up stuff before you can even say 'I can't be arsed taking the carbs off and cleaning them'.... It's not a hard job if you follow the haynes, you'll get quicker at it every time.

I clean out my racebike carbs between track time as fuel gum blocks bits up very easily. 2 months of sitting will do it, especially in warmer months when fuel evaporates more quickly.

[tazbert]

Thanks for that!

I was thinking if a jet was blocked it would:

a) be running rough as a cylinder was not getting the same fuel as the others and

b) be using less petrol!

will get the carbs off some time, bought some extra long screwdrivers the other day
to help get those ^%&^$£&* carb rubbers undone...

Thanks

Andy

[Cammo]

Thanks for that!

I was thinking if a jet was blocked it would:

a) be running rough as a cylinder was not getting the same fuel as the others and

b) be using less petrol!

No. You'll be using more throttle to get the same sort of performance as standard. More throttle equals more fuel from the carbs that are working, regardless of what isn't working.

Get those long screwdrivers to work!

[tazbert]

Get those long screwdrivers to work!

yup, just got some 450mm ones from screwfix.
nearly lost an arm last time i tried to get to those carb rubbers!

cheers

andy

[Waza4]

Check the choke linkage isn't sticking as well.