Can I use a different/better carburetor on a taotao 135cc atv?

Thank you

 

Id think there are a few different carbs out there that would work. What are you trying to gain with a swap?

 

I have just joined this forum, hoping for some insight into whatever could be ailing my son's ATV.

Bought it 11 months ago. Ran fine, as soon as I figured out that the handlebar kill switch had a tendency to work its way loose and kill the engine all by itself.

Couple of weeks ago, he was racing around our property and it just died. Couldn't get it going again, without removing the guts of the kill switch on handlebar. However, it is now bogging out on high throttle. Idles fine, but as soon as he takes off and gives it some gas, it starts coughing and spluttering like someone who smokes 40 a day!

I have removed the carb, pulled out the jets, cleaned them and everything super well (used to have a 1966 BSA in the UK so got lots of experience with carbureters), cleaned the air filter, removed the gas tank, flushed and cleaned absolutely everything - no change.

Changed out the CDi box, changed the coil, changed the spark plug. Now I am just mad with it. It is coughing and backfiring when we give it some gas, almost like the timing is off. Everyone tells me that it is carburation, but I have screwed the mixture screw in and out a bit at a time so many times and it makes no difference. Any ideas anyone? Could it be that removing the guts of the kill switch has somehow upset the CDi box? Might be a daft question, but I do not know much about how those boxes work. Can't get the ATV to start with the guts in the kill switch though. Starts up like a champ but only idles well, and won't reach any real speed without the hesitation and spluttering. Using 93 octane as recommended. Maybe removing the guts of the kill switch has messed up the rev limiter? So frustrating!

 

The kill switch usually just shorts the "kill" wire from the CDI to earth.

Depending on the type of ignition system you have, overcharging by the regulator can cause misfiring, so check the voltage across the battery doesn't go over 14.5v with the engine running.

Regarding carburation, the plug nose colour can give some indication, white and it is weak, black, rich and dark grey with whiteish porcelain, about right. This can only be checked after a long run as the choke affects it on starting.

 

I can certainly check the voltage across the battery. This ATV, Tao Tao 150 CC has a rectifier. Not sure if that is the same thing as a regulator?

 

might also check valve lash

 

Quick update. I checked the voltage across the battery. At full throttle, it steadied out at 15.8 V, but at lower revs was around the 14V mark. Hopefully that is within tolerances.

After fiddling around with it some more, I discovered that it was pulling air at the base of the goose neck from carb to engine manifold. No idea why I didn't check there before. The bolts all over this machine just loosen off every few hours.

Whilst it is still a little rough, before I could spend any more time tweaking air/fuel mixture, my son jumped on it and that was that.

If you think the voltage is too high, merryman, please let me know.

 

I would change the regulator. At 15v I would probably leave it, but 15.8v will not be doing the rest of the bikes electronics any good. AC charging systems need both a rectifier to change AC into DC and a regulator to keep the voltage below 14.5v. These are combined in one unit so the terms regulator and rectifier are interchangeable on quads. Your old BSA would probably only have a rectifier, the feeble output of the alternator didn't produce many volts and there were no other electronics to worry about. It is just possible the Chinese maker has gone down the same route, as some CDI ignition systems are completely divorced from the charging system.

 

I think that isn't good idea