Hi fellow users ,

i'm having a problem with my TXT.

I'll try and scetch what happens.

When i go and play on my nearby mountainbike paths (aprox an hour or 1.5 hour length) ,

my bike cuts out.

Just no fire...

Sometimes 2-3 minutes after refueling , sometimes from the moment i leave (filled gastank 5 minutes prior to that)..

And ONLY when i'm on the public roads , riding at 60KPH constant throttle,

the moment i let go of the trottle...

Never when i'm riding in the woods.

It feels like i'm out of gasoline , but sometimes 2-3 minutes after refueling.

Things i've tried/done :

-Changed the tank's tube on top (to prevent / fix a blockage , so there is no vacuum)

-Changed the sparkplug

-Changed sparkplug holder

-Changed Sparkplug wire

-Changed Piston

-Cleaned the killswitch on the stearing wheel

-Cleaned the killswitch on the radiator hose

Anyone that can help me with this?

you didn't mention checking the filter in the fuel tap

and you've got some pretty bizarre things going on there (a steering wheel and a kill switch on the radiator hose)

Edited November 19, 201312 yr by feetupfun

The tap filter?

Is that a filter on the fuel line?

There isn't one , i filter my fuel before mixing.

The tap filter is inside the fuel tank and is attached to the fuel tap. Filtering the fuel as it goes in is a noble act, but this filter may still be causing a restriction to flow.

You did say you changed the tank cap hose, but didn't say that you tested the fuel flow rate to the carby. That would prove if there were any problems with fuel supply caused by tank vacuum or flow restriction.

It is also possible to get a vapour lock in the fuel line that stops the fuel flow. I can't see the fuel plumbing on your bike to know if that is a likely problem or not

I think he meant the kill switch on the handlebars and the mapping switch below.

this may be why? i was reading the gasgas uk ssdt preperations manual and it says its critical not to run the bike on the road at a constant throttle because it causes the mixture to become weak and run very poorly and damage it or will not work like in your case.

when on the road make sure your using 100mls to 5 litres of fuel of 2 stroke oil as theres lots of stress on the engine. but most importantly you must never keep a steady throttle becuase i bet thats whats causing it to cut out! it never happens in the woods does it because the throttle is constantly being varied!

hope that helps or makes sense lol!

ben -13

When riding on smooth surfaces such as roads the floats can stick and not allow fuel into the float chamber; this would explain why you have a problem on the road but not off road. Make sure the floats are really free on the pins inside the float bowl.

Does the bike rev up before it quits? That is a common indication of a super lean condition as a bike runs out of fuel. Other's have suggested checking adequate fuel flow to the carb including sticking floats. Those are great ideas.

Here is another more obscure idea. Are you losing coolant from the radiator? Perhaps it is an overheating problem. Trials bikes run very low amounts of oil per gallon (or liter) and very small radiators, compared with most street or trail bikes. Running at continued high RPM's can lead to very hot running inside the engine. This can cause a light seize. How do the piston look when you changed it? I have heard that during some of the world championship events with long road transits, the riders often ride with their choke on to make the mixture richer to provide more internal cooling.

could be that your carb bowl isn't holding enough fuel because the float height is too low and at constant high revs its running dry, but I would check fuel flow first, and if you have a dellorto carb clean the banjo filter on the side where the pipe is attached to carb.

TLTEL

Ok thanks guy's!

I'm gonna take this step by step.

I'l try the throttle postion first.

I can fully understand this theory

Then the flaoting chambers.

Then maybe enlarge the carb bowl.

I'll keep this thread posted , is someone in the future should have thesame problem.

You need a bigger float valve read gas gas ssdt prep

Well...

Went for another ride last saturday...

1st hour , nothing happened.

Watching my throttle movement on the longer straights (especially roads).

Everything went fine.

Stopped over at a friends house ,

refueled.

Only 500 meters later , it cut out again.

Triad watching the throttle positioning.

Couldn't get it stable , nor running longer then 2-3 minutes without it cutting out.

And it's not like the piston is creeping , my rear wheel isn't blocking.

I can tell from the casual exhaust "puff" that the engine is still turning.

But the moment i give a little throttle , it totaly cuts out.

Any sugestions what my next step should be?

The other thing you could check is that the gas cap is venting properly, The fuel in the tank gets warm when riding off of heat from the engine, and if you add fresh (cooler) fuel to the tank and then put the cap on, it will pull a vacuum if the cap is not venting properly. Just one of many possible explanations, but where I would start. The other thing would be changing to a clear fuel line to rule out if it is a fuel starvation issue.

Edited December 2, 201312 yr by mickl

The other thing you could check is that the gas cap is venting properly, The fuel in the tank gets warm when riding off of heat from the engine, and if you add fresh (cooler) fuel to the tank and then put the cap on, it will pull a vacuum if the cap is not venting properly. Just one of many possible explanations, but where I would start. The other thing would be changing to a clear fuel line to rule out if it is a fuel starvation issue.

Just pull the fuel cap when it starts to do this as an easy test.

Another thing I have heard of is a loose airbox to carb boot. It blocks the lower ports on the carb from getting a correct fuel mixture as you wack the throttle open. Why all of the sudden? The seat is the air box and if its loose at all it will allow that rubber bushing to move around as you sit down on the seat. If your sick of that rubber bushing between the carb and the seat (as i have been in the past) then get yourself one of these.

--Biff

I understand that it sounds like fuel. I have seen several bikes with poor connections at the cdi. Make sure all the pins are pulled out in the proper placement at all the plugs in the wiring harness. Would hate to think you are chasing the wrong problem.