Starting Problems

[kingkay7]

Hi Guys, I had an issue recently with a lexmoto XTR s 125 where it wouldn't allow me to go above 3000 rpm when using throttle. The issue has got worse and the bike won't start at all. I have noticed the following which I believe could be the problem but would like a second opinion:

Inlet: Split at engine side, only a small crack in the metal, rubber is still intact

Tank: Found rust in the tank, flushed it out but I don't think it's helped

Petrol: Coming out a golden colour

Spark: After cleaning carb, it will ignite and rev but die quickly. Took spark plug out and put it against the frame and was getting a blue spark.

Plug: Wet with fuel - adjusted fuel screw but still a bit wet ( not igniting so I guess it would be )

Root Cause: Combination of the above possibly? Split in inlet losing air, dirty fuel ( could it be that bad it won't ignite? )

Would really appreciate some advice, or if anyone in the edinburgh area cares to have a look?

[Tango]

A split in the inlet manifold will certainly not be good......get that sorted and see where you go from there.....

[kingkay7]

Thanks Tango, I have ordered a new one.

If the tank has rust in it should I order a new one? Could anything else discolour the fuel to a golden colour?

GK

[Tango]

Petrol is a kinda golden colour anyway.......but check the fuel filter and make sure there isn't a load of rust clogging that too.....

[Lumor_uk]

I'm guessing it doesn't have a fuel filter so get one fitted. Ask for the smallest one at your local motor factor. No need to replace the tank just don't let it run into or near the red.

You might need to give the carb a clean out if it's full of rust

[kingkay7]

Thanks Tango / Lumor,

You are correct Lumor, no filter. In my ignorance, I didn't even think about it.

I have been in and put an order on the inlet manifold and a fuel filter. The manifold won't be here until Monday so will need to wait

I am also going to give it an oil change incase any fuel has got into the sump when it has not been starting.

[Lumor_uk]

won't fuel only get past if your piston rings are worn and it was smoking out of the exhaust before your problems? oil every 6 months or 1k miles I think.

I love the rust in the fuel symptom, brings back memories of my first fix / work on an engine. it was a £75 1.1 1984 fiesta in 2001. it had stopped running well, took apart the mechanical fuel pump and the fuel was orange. I had the biggest grin on my face that I fixed it without a manual or training.

[kingkay7]

Hi Guys,

Managed to get to run again however its gone back to the whole any throttle and it stalls. It appears that its something to do with the two small pipes at the bottom of the air intake side ( not sure if they are intakes or not ). I have added a picture with the two pipes.

When I cover them, the bike runs and revs fine. When they are uncovered, it sounds as if when the throttle is used or choke is off that air is escaping from them making the bike run rich. I have two carbs for the same bike and both are running the exact same way.

I can't see anyway of adjusting what happens with these, I guess it wouldn't be advisable to permanently cover these up? Or certainly the problematic one.

Cheers again guys.

[Lumor_uk]

have you stripped the carbs? are they both second hand? have you checked what happens with the air box pipe connected? it looks exactly like the cg 125 carb. I spent many weeks looking at the bloody things 3 years ago. but completely forget where those two holes go to. strip a carb to see and that will give a better idea of what's going wrong. too much air will make a bike run rich. the bikes are tuned to run well with restricted air flow.

[kingkay7]

Hi Lumor,

I stripped them, the left goes to the pilot and the right to the main, I suspect its the right one that's causing the problem, either extra air coming in, or losing air making an extra rich mixture. If when I find out what it does, I am tempted to block it if the bike runs well without it. Would you agree?

I know its part of the design and must serve a purpose but for the lift of me I can't find it, I have searched google for 2 hours and nothing! Both carbs, 1 new and 1 old have not been correctly assembled in the first place ( I have no idea why ) but both did not have the acc pump correctly put together, not sure why its needed tbh but anyway.

Cheers,

GK

[Lumor_uk]

I can't remember correctly but is there supposed to be a washer inside the pilot screw ? if you take it all the way out and check. I think there's a spring in there too so don't lose it. the original screw position is 3 turns out. so completely screw it in tight. then undo 3 turns.

is it part number 1?

http://images.cmsnl.com/img/partslists/honda-cg125-1993-singapore-carburetor_bigeccsp81e__1500_6bda.gif

http://www.cmsnl.com/honda-cg125-1993-s ... ml#results

[kingkay7]

Yeah there is a small washer on the pilot screw