Carb issues......?

Question

Im in a dilemma, put new piston in bike, rebored and new rings its all good in that respect....but now it seems there is no fuel getting to carb, this is not a problem i had before. I guess im really looking for a diagram of a carb fitted or even a photo that i can compare to. The lines are clear the fuel filter is clear, its not old petrol, and its not been stood. Because i did the piston and timing myself no garage is prepared to take it now. i have compression and if i put fuel direct into carb it works.
Any links to sites much appreciated.

Model; Yamaha XT125 4-stroke (2005)

Answer 1

Hi Jimi,,,



I know how cars' steering wheels are in the UK,,

But on the Bikes,,which side do Y'all put the handlebars on?

;)



................................

We Yanks can't see any data on XT125's.



But the TTR 125 version uses same carb and hose set-up.



Here is a TTR 125 '05 Factory Service Manual You can download.

It's from Yamaha Australia



http://www.yamahaownershandbook.com.au/lib/download.php?f=1B2-28199-80.pdf



If that link doesn't work,,,

Go Here:

http://www.yamahaownershandbook.com.au/?r=0

>Select MOTORCYCLE

>Enter model name (__125_)

>Select model year(__2005__)



Then Download the TTR125 Manual.

It's Fairly Big,and slow.

I suggest Saving it on your PC in "My Documents"



..........................................................

When you finally get it downloaded and Opened,,,

Grab the Scroll Slider on the side of the PDF Thingie,,

Pull it Down while watching Page Counter at bottom center of page.



CARB starts in Section 4~3,,

which is page 264 .

Just Quicker and easier to drag the scroll slider directly to that page.



Look at page 480 for some clues about Which hose goes where AT The CARB



Look at page 154 for overall Hose Routing



I Suspect Fuel lines may be crossed with Vent lines .



If Fuel is coming out of Fuel Line when gascock is ON,,,

That leaves a Stuck Float Needle or a blockage in the carb as just about the only possibilities.



The Other good fellows have already covered most all the possibilities.





One VERY odd,,off-chance thing is this...

While you had fuel tank off the bike,,,theres a Slight Chance it accumulated some condensation.

Any sloshing while Re-Installing tank would have rinsed that down in tank to settle at bottom.



Which would have give carb a small sip of water when You 1st open the Fuel tank.



Water is much heavier than Petrol,,,and it SHOULD settle into bowl of carb,,,,where draining the Carb bowl would eliminate it.



However,,,if by Some chance it DID have that water,

and it Did suck any into one of the jets,,,

Simply draining the Carb wont eliminate the water inhaled INTO the Carb's Air/Fuel circuitry,jets,etc.



The chain of events Required to cause all that,,is next to Impossible.

But it IS Possible.



If Carb can be verified to be getting adequate fuel,,,

But "ENGINE" is getting none,,,,then the Fuel is blocked somewhere WITHIN the Carb's circuits.



Carefully remove the jets and blow them out with Air,WD-40,Carb Cleaner Spray or whatever.

Tighten them upon re-installation Carefully,,Only SNUGLY,,,not actually "Tight"



...........................

Occasionally a Carb's Float will simply get physically Jammed,,,stuck in closed position.



Occasionaly water or debris from Fuel Line Wont go Through the Float Needle Valve,,,but accumulate on top of valve inlet.

Simply remove fuel needle valve Seat that's screwed into Carb Body and have a look.





I'm not certain of exactly how You introduced fuel to get engine to start,,,,,,But That's a Good Sign & reassurance Your Motor Work is Good & all in order.



If You added the Fuel thru Air Intake,,,,,that indicates actual Carb Blockage internally.



If you somehow added fuel thru the Fuel Inlet Pipe on the Carb,,,,that suggests there's No Delivery from Tank/Gas Hose.

In that case ,,Crossed Hoses ,,Vent vs Fuel,,,would be the obvious suspect.





If you need to dismantle carb,,,the Manual has a parts blow-up

Diagram,,,and some rather feeble instructions.

But it's probaly plenty enough to get you through



The FRUSTRATION LEVEL may be SERIOUS by now,,,

But I'm sure there's nothing Serious wrong with Your Bike



Hope any of that helps,,,Good Luck.

Answer 2

hmmmmm, pull the hose that goes between the tank petcock and the carb off the carb end to insure fuel is getting that far.... if you don't have gas there, try turning the petcock and/or pull the petcock out of the tank and clean the screen.



if you do have gas at the carb end of the hose, reinstall hose and pull the carb drain screw from the bottom bowl (float bowl) of the carb to see if you have gas there. if no gas there, pull the carb off the bike, pull the float bowl off (probably removal of 4 screws) to inspect the float, needle valve, main jet, etc. and clean thoroughly with carb cleaner (like b-12). the float needle might be stuck, not allowing fuel into the bowl.



here is a diagram for an 2005 XT225 (didn't find a XT125 but this should be similar in principle) that might help on how it comes apart / goes together. http://houseofmotorcycles.bikebandit.com/parts/Yamaha/XT225T+XT225/2005/1122613



how long has the bike been not running (when was it last run prior to doing the top end???)???

Answer 3

Do you have a workshop manual for the bike..if not get one.



Is the fuel tap on the fuel tank working ? pull the fuel pipe off the carb and see if fuel is flowing thru it when you turn on the fuel..........is there fuel in the tank ? is the fuel tank tap filter blocked (its inside the tank you need to remove the tap) ?



Is there a vaccumn tap on your fuel tank ? (I dont think so though - if there was the fuel tap only open with the vaccumn action of the carbs and you'd see another small line from the carbs to the back of the tap !!)



Open the little drain screw at the bottom of the carb float chamber and see if fuel is draining out...it should be...if its not the no fuel is coming from the tank...again check the tank, the tap, is tap on ? is there fuel in the tank ?



Er.

Answer 4

Simple answer either your float is set too low or the needle valve in the fuel line on the bowl is clogged.