troubled serrow

[mally]

Hi, my serrow runs sweet from tickover to third throttle then splutters and wont pull. carbs been of checked and cleaned,another cdi,coil,lead,plug,staters been rewound and connecters have been cleaned anyone any ideas or a box of matches please.

 

[Timolgra]

Main jet

 

[Paul G (BHT)]

Mally,

Sounds like it may be over fueling, mid throttle fueling is normally linked to the needle and main jet.

Check the needle height and main jet are correct and that the needle hasn't been 'lifted' in the slider.

 

[Timpo]

Chech balance pipes aren't blocked. They hang down from carb to below swingarm pivot.
Also make sure tank is breathing.
Can you hold it at half throttle to accelerate or is it flat as feck?
Check earth lead is connected properly, both to battery and frame.
I'm not sure what carb is on your model? Does it have a fuel pump diaphragm. These can perish if bike has been standing for some time.

Timpo.

 

[Brian E]

is this a problem that has just started or has it always been doing it since you got the bike?
I agree it sounds like main jet but i am also thinking it's a fuel supply problem maybe the filter in the tank or is there a filter in the tap or maybe there is a problem with the fuel vent hole in the petrol cap causing a vaccumm in the tank. is the silencer to blame and the silencer needs a decoke.

 

[mally]

carb rubbers ok its been cleaned and checked ,bike drove in to hut and next day fecked.will try earths and see what happens,thanks for advice.filter and tank both been cleaned out.

 

[Breakfree]

I got one too

I have bought a Serow with exactly the same problem, did you cure yours or maybe you sold it on and I've eventually bought it? D***YHK?

I have cleaned every part of the carb, the nylon washer is in place below the circlip, the diaghram and inlet rubber tubes appear to be in perfect condition. The air box and exhaust are not restricted, the throttle is operating for it's full 90 degrees, the petrol is fresh, the plug is a lovely colour, I'll try a new one anyway. There is no spitting from the carb or exhaust at any revs, it just dies at one third throttle. It starts perfectly. I cleaned inside the flywheel and removed a thin dust of carbon from the oily surfaces.
I took it into a local motorcycle dealer who also checked the carb but then he ignored it for three weeks so I 're-posessed' it and now I have it to fix myself.

I wondered about the coil not being up to it's job but it looks new, maybe the capacitor breaks down at high revs, they are not easy to check without others to swap with and that can be an expensive trial and error.

Any further suggestions, local owners who might swap spares before I buy new ones, or the name of a trustworthy repair shop will be appreciated.

Best regards
John

 

[Breakfree]

I got one too

Another thing I forgot to mention, reading the replies earlier, the carb has a float chamber so if the filter was blocked the engine would run normally until the supply diminished, it would then falter. Mine falters on a full chamber.

John