Newbie needs some help!

[kingkay7]

Hi Guys,

I have an Lexmoto XTR S 125. I have just had it MOTd. I know I shouldn't have bought one but I own it now and need to deal with it.

I am now having a problem where by, I left it idling for 10 minutes then went out on it. First 5 minutes it was fine, then revs started fluctuating then when it was in gear it would lose all power and stall after a few seconds, below is what I have checked:

* No kick stand switch

* When slipping clutch out, I give it some throttle

* it revs fine in neutral

* When trying to change gear after it has stalled it becomes very tough

Really starting to bug me, is it a problem with the transmission / gears or possibly clutch cable?

I have just had to adjust the fuel and idle screw to get it running as after the MOT it stalled after riding it which I believe was a poor air/fuel ratio as it would only run at about 3000-4000 revs minimum.

Many thanks all.

[Tango]

Welcome to the forum mate......say hello in the newbies section when you can.......

Check the basics first.......oil, plug, air filter, etc.........

Also check tank breather.......

Check these and let us know what they are like and we'll see where we go from there.....

[kingkay7]

Welcome to the forum mate......say hello in the newbies section when you can.......

Check the basics first.......oil, plug, air filter, etc.........

Also check tank breather.......

Check these and let us know what they are like and we'll see where we go from there.....

 

Thanks Tango

Oil looks fine, new air filter, plenty of fuel, fuel is getting down to carb alright, throttle slide moving nicely.

The tank breather, is that the hollow rod between the bottom of the tank up to the refiller cap? Or is it the vacuum part of the fuel valve?

Sorry fairly knew to this but I am a quick study

[acting_strange]

Welcome to the forum mate......say hello in the newbies section when you can.......

Check the basics first.......oil, plug, air filter, etc.........

Also check tank breather.......

Check these and let us know what they are like and we'll see where we go from there.....

 

Thanks Tango

Oil looks fine, new air filter, plenty of fuel, fuel is getting down to carb alright, throttle slide moving nicely.

The tank breather, is that the hollow rod between the bottom of the tank up to the refiller cap? Or is it the vacuum part of the fuel valve?

Sorry fairly knew to this but I am a quick study

 

Without a tank breather, as fuel is used in a tank it will create a depression or vacuum above it which will eventually stop fuel flowing. A tank breather allows air to flow in and stop this hapening...its ususally just a pin hole somewhere in the filler cap..

If you want to see what I mean just get a 1/2 litre beer bottle (empty it first) fill it with water and put your thumb over the neck. Turn it upside down and gently let your thumb off to allow the water to flow out...eventually it should stop but there will still be water left in the bottle...

[kingkay7]

Welcome to the forum mate......say hello in the newbies section when you can.......

Check the basics first.......oil, plug, air filter, etc.........

Also check tank breather.......

Check these and let us know what they are like and we'll see where we go from there.....

 

Thanks Tango

Oil looks fine, new air filter, plenty of fuel, fuel is getting down to carb alright, throttle slide moving nicely.

The tank breather, is that the hollow rod between the bottom of the tank up to the refiller cap? Or is it the vacuum part of the fuel valve?

Sorry fairly knew to this but I am a quick study

 

Without a tank breather, as fuel is used in a tank it will create a depression or vacuum above it which will eventually stop fuel flowing. A tank breather allows air to flow in and stop this hapening...its ususally just a pin hole somewhere in the filler cap..

If you want to see what I mean just get a 1/2 litre beer bottle (empty it first) fill it with water and put your thumb over the neck. Turn it upside down and gently let your thumb off to allow the water to flow out...eventually it should stop but there will still be water left in the bottle...

 

Thanks Acting Strange.

I just had a look and put a torch to the underside but couldn't see any light coming through, either blocked or kinked. Going to get a thick bit of earth and put it through to see if that helps. Will report back soon.

[megawatt]

Don't get mixed up with breathers and vacuum tubes. A breather allows air at atmospheric pressure into the tank or carbs to allow the fuel to flow out, or an engine breather allowing engine fumes to escape to the airbox usually. A vacuum pipe is usually a connection between the inlet side of the engine/cylinder head and the fuel tap, to allow fuel to flow with the engine running.A vaccum pipe should never be open ended, a breather should.

[rennie]

I think we might be jumping the gun a bit here!

Basics first

Is there any fuel in it? Is said fuel clean and fresh?

What does it do now if you try to start it from cold?

Is the choke (if it has one) on or off?

[kingkay7]

I think we might be jumping the gun a bit here!

Basics first

Is there any fuel in it? Is said fuel clean and fresh?

What does it do now if you try to start it from cold?

Is the choke (if it has one) on or off?

 

Hi Rennie,

Went back and checked as you said again, fuel is clean and fresh, starts when choke is off but not when it is on.

Guys, I have however found a tiny hole in the petrol pipe to the carb, after taping this up it is allowing me to run around in 1st and 2nd ( only tried it in the yard ). However the engine was extremely warm, took the spark plug out and it was carbon black,does this point to being to rich?

The fuel screw is out about 4 turns, but if I put it in any further I either get a really rough idle ( both cold and warm ) or it doesnt start, this is will adjusting the idle screw to compensate for idle RPM

Thanks guys again, you are all helping me learn and get this death trap running!

[acting_strange]

I think we might be jumping the gun a bit here!

Basics first

Is there any fuel in it? Is said fuel clean and fresh?

What does it do now if you try to start it from cold?

Is the choke (if it has one) on or off?

 

Hi Rennie,

Went back and checked as you said again, fuel is clean and fresh, starts when choke is off but not when it is on.

Guys, I have however found a tiny hole in the petrol pipe to the carb, after taping this up it is allowing me to run around in 1st and 2nd ( only tried it in the yard ). However the engine was extremely warm, took the spark plug out and it was carbon black,does this point to being to rich?

The fuel screw is out about 4 turns, but if I put it in any further I either get a really rough idle ( both cold and warm ) or it doesnt start, this is will adjusting the idle screw to compensate for idle RPM

Thanks guys again, you are all helping me learn and get this death trap running!

 

Yes a black plug is usually a sign of an engine running too rich.....but checking after tick over can also do that....an engine needs to be warm and run at higher revs than tick over before removing and checking plug. The screw that makes it run rough...get the engine warm...make sure the choke is fully off...the screw it in until in runs rough then back it out 3/4 turn...

[kingkay7]

I think we might be jumping the gun a bit here!

Basics first

Is there any fuel in it? Is said fuel clean and fresh?

What does it do now if you try to start it from cold?

Is the choke (if it has one) on or off?

 

Hi Rennie,

Went back and checked as you said again, fuel is clean and fresh, starts when choke is off but not when it is on.

Guys, I have however found a tiny hole in the petrol pipe to the carb, after taping this up it is allowing me to run around in 1st and 2nd ( only tried it in the yard ). However the engine was extremely warm, took the spark plug out and it was carbon black,does this point to being to rich?

The fuel screw is out about 4 turns, but if I put it in any further I either get a really rough idle ( both cold and warm ) or it doesnt start, this is will adjusting the idle screw to compensate for idle RPM

Thanks guys again, you are all helping me learn and get this death trap running!

 

Yes a black plug is usually a sign of an engine running too rich.....but checking after tick over can also do that....an engine needs to be warm and run at higher revs than tick over before removing and checking plug. The screw that makes it run rough...get the engine warm...make sure the choke is fully off...the screw it in until in runs rough then back it out 3/4 turn...

 

Thanks acting strange, I will try do this now, its a pain to get to. Whoever designed these really didnt have their thinking hat on. Its a screw on the bottom of the carb at engine side with only 20mm access. I don't have the special screw driver to turn it so have to use my hand, when doing this though it obviously burns me haha. I'll come up with a plan but many thanks for your advice, maybe get to take it out tonight.

I guess if its running rich that is why it was so hot? This bike was designed so bad, to get the spark plug out you need to use a spanner ( socket won't fit in due to frame ) so I will pick up another plug tomorrow and try it after making this adjustment.

[Tango]

Check the connections between the carb and cylinder head and airbox as another lexmoto rider on the forum had trouble with a split in the rubber.......on a bike that is less than 6 months old.....

[kingkay7]

Check the connections between the carb and cylinder head and airbox as another lexmoto rider on the forum had trouble with a split in the rubber.......on a bike that is less than 6 months old.....

 

Thanks Tango, I did originally have a problem with that but got a new airbox and carb boot. Both still in tact.

Took it out there and again it happened, but when in neutral I revved it a bit more. At 3k revs it stalls, in gear or not.

[acting_strange]

you may need to take the carb off and check the float level as it sounds like you are running out of fuel at revs...fuel starvation...just read somewhere about a worn float needle causing a problem..

[kingkay7]

you may need to take the carb off and check the float level as it sounds like you are running out of fuel at revs...fuel starvation...just read somewhere about a worn float needle causing a problem..

 

Thanks Strange, I have another carb inc float at my parents house. I will try that on, hopefully it won't have the same problem. I tried another spark plug - clean, and it still does it.

Would it be wise to reset the carb? Knock it up to 3k revs and start adjusting the fuel screw? Now it doesn't sound like its running correctly

[kingkay7]

I did some testing just there, if I adjust idle screw it will reach 4-5k RPM, possibly higher but I just wanted to check. Would this mean it has something to do with:

Needle Jet

Main Jet

Throttle Slide

....

As I said I am going to try the other carb out see if that improves anything tomorrow / Wednesday.

[eastanglianbiker]

the mixture screw should be set at tickover to start with have the bike idleing and start with the screw between 1 and 1 1/2 turns out the tickover screw should be setso that it will tick over at 1100-1200 to aid with setting up

[kingkay7]

Hi Guys,

Put the other carb back in yesterday after giving both a very good clean. Currently its not starting and I didnt want to play around late last night and annoy the neighbours.

It seemed both carbs were adjusted almost exactly the same, where this one wont start which I see as a good thing??? As it could have pointed to something bad on the original ( or could point to something bad here )