Fueling issue.

[dudehog]

Tried to post on my other thread and use the search function but I keep getting "page not found" on my comp. Stooopid technology

So Here is what I have changed:
Petcock valve
Spark plugs
Front coil
Balanced carbs

When I go above 4krpm she splutters on very light throttle. Below that i can ride along and get puffs back through the carb. Upon inspection it is through the rear carb.
Under acceleration she pulls like a train in all gears right up to the redline. Above 4krpm, open it up full and there is a very light hesitant cough.
Let go of the throttle and it decelerates fine.
It ticks over just fine.

Now one member said about the pilot may have crap in it? How hard is that to clean?
The rear head has a spark but is a coil the problem?
This has literally happened over night.
Is is not filling the carbs fast enough?
Any advice greatly received

[Anotherbikerbabe]

Guys, I've been trying to help this member and we have been through the whole airbox/fuel tap bits eyc.. C'mon guys, you lot a re great at putting your heads together and coming up with solutions!

[MacV2]

Pilots with crap in them aren't a problem really.




Once they take off they can use the loo...Unless its a single seater then they have to hold on to it until they land...




What you describe as 'puffs' are know as 'carb farts' they all do it to a certain extent.

Check you TPS reading for a start.

It may be something a simple as an air leak in a carb rubber.

[dudehog]

Ah, you say about the TPS. What would happen if it was running and I unplugged it (whilst running)?

[dudehog]

"Once they take off they can use the loo...Unless its a single seater then they have to hold on to it until they land..."

Explain?

Also I get the carb farts but more than I should. Again. that came overnight.

I may toy with the idea of stock needles/pins. I know I have a bigger jets fitted.

[MacV2]

Ah, you say about the TPS. What would happen if it was running and I unplugged it (whilst running)?

I guess the ECU wouldn't know the position of the throttle is the simple answer...

Although I'd advise against trying to do it whilst running along side the bike...

[dudehog]

Ok because my bike runs the same with or without it connected. Has done since I got it last year.

[MacV2]

"Once they take off they can use the loo...Unless its a single seater then they have to hold on to it until they land..."

Explain?

Really ?

OK then. Pilots fly aeroplanes, if they want a crap they will need the toilet. Bigger aircraft have loo's on board. So once they have taken off they can use the loo. Single seat aircraft don't have loo's so the pilot's have to wait until they land to go for a dump or the sensible ones go before take off. This also has the advantage of saving weight.

Has that explained it ?

[dudehog]

Er....I guess. Random.

[MacV2]

Er....I guess. Random.

Nowt random about that Mate.

In your OP you mentioned crap in pilots...

[dudehog]

Ok. Would those pilot things in my carbs being slightly clogged cause issues at very light throttle?

[NZSpokes]

Ok. Would those pilot things in my carbs being slightly clogged cause issues at very light throttle?

Yes.

[dudehog]

Ok.
How does the fuel tap diaphragm work under vac? when the engine runs, is it permanently open?

[Anotherbikerbabe]

Me: do you get petrol coming through the bottom vent hole on the fuel tap ( cos you shouldn't)

Member:: The tap. It's seated ok. It pulls like a beast up to 9k....

Me: they do but then they run out of fuel
so when you throttle off it gives the vacum time to build up the fuel in the flo chamber
cos the vacum pulls the fuel back through and fills the fuel chamber so it feels normal again,you'll need to check the diaphragm and the seating inside the tap..
Member: New diaphragm, so it's not that..

Me: and you've not cleaned the carbs?

Member: Nope, not taken them apart...

Me::: hummmmmmmmmmmmmmmmmmmmmmmmm thinking.... What speed does it start coughing? and how long do you hold that speed?

Member: above 4krpm. usually after hard riding.
Me: Sounds like fuel starvation...

Me: Check and triple check the seating of the new diaphragm, fiddly as owt piece of nothing to fit:when dave put a new one in, he actually had a piece of hose that he attached to vacuum inlet on the fuel tap n sucked on it to pull the diaphragm into place while he was assembling it

[NZSpokes]

Ok.
How does the fuel tap diaphragm work under vac? when the engine runs, is it permanently open?

Easy test. Lift tank and unhook one of the fuel lines. Unhook the vac line from the petcock. Find a bit of hose that fits the valve and suck on it. If fuel flows the valve is working.

Which i would say it is working.

Clean out your jets.