Ok, I have a 08 Tao Tao 150cc that is driving me nuts.
It has the slide type carburetor on it that has the cable coming in from the top not the side.

It came with a 30mm carb on it and the factory air box. The intake, carb, and CDI are all parts from a 250cc and this is what the quad came new with.
The 30mm idled, but would not run open or anywhere in-between.

I replaced the 30mm with a new 30mm and the quad idled, but on higher rpms bogged(too lean) and spit gas out of it. I found this to be due to the fact that the intake opening is 24mm. Gas was clearly back splashing.

The bike was then checked for timing, compression with gauge, and any obvious air leaks. All tests were clear, no leaks, no cracks, no timing issues.
I then dropped the carb to a 27mm and the problem persisted, too lean, bogs above idle.

I then ordered a 24mm and yet the same problem.

I have tried to use the factory airbox in the event that it was restricting enough airflow to balance the carb. No dice.

I then obviously made a hundred adjustments to the carb both up and down for metering and no change. I did with all 3 carbs.

I also changed the CDI to a performance model and that slightly helped. I also changed the plug.

So far the quad will start instantly, bog on any mid-range, and roar like a beast on WOT. I really want to get this quad to run right, but after 3 carbs I am at a loss. It is clearly a fuel issue as the motor itself is solid with no apparent air leaks. I have a ton of spark and do not think that I would loose spark at mid-range.

Any help or other ideas is helpful. I am at the point of just selling it back out at a loss.

 

i had a hibird 250 that had a similiar problem, i made sure my rich/lean mixture screw wasn't stripped out and not making any adjustments for me. once i got close to the correct setting there, i moved the slide needle E clip to the middle groove after i cleaned the carb. then for some reason, all of my problems with revving went away. i don't know if it was a needle adjustment or cleaning the carb for the last time, BUT, it worked whatever it was...sorry.....my wifesquad helped me out on that one........

http://forums.atvconnection.com/chin...e-problem.html

 

Nope, moved the needle and no change.
I am going to pull an inatke and 30mm off of my other 150cc that I know has no problems. The only problem is getting a fit to the other frame.

I am also going to use the pilot jet from another 30mm carb on the 24mm carb and see if that helps.

I really hate when they don't run.

 

Ok, today I took the intake/carb(mikuni style) off of the other 150cc that runs great but has a bad gear box. This carb is adjusted properly and it started and ran instantly.

I installed the 30mm carb onto the Tao Tao and it started instantly but still had the same problem as 4 other carbs. It idles up and down, no mid-range, and bogs out when trying to throttle from an idle.

I have checked every possible avenue for an air leak and there are NONE!

This leaves me with the only other choice that this problem is electrical. I changed the CDI to a Casoli high performance CDI and it did run better. The quad starts instantly, idles up and down, and runs WOT but nothing else is any good.

I am now thinking that it could be a problem with the pick-up coil. I am going to change the actual coil out this weekend. I have already changed the spark plug.

If a new coil does not fix this problem, than will I need to change the stator?

This bike has been a real Pain in the butt! I drove it a few times with the carb acting up but when it would ramp up the quad would fly! I really want to get it running so I can use it. Any help would be appreciated.

 

I must say from the start that you are far better at solving carburetor problems and engine mechanical problems than I am. My expertise is over a narrow range of electronics, so when considering my advice you need to put boundaries around what I say because I have limited direct mechanical experience.

I can't think of any problem with the trigger pickup coil that would fit your symptoms. Usually problems with the trigger coil involve starting problems because the trigger output voltage is proportional to engine speed, and cranking speeds (600 RPM) is far lower than 1500 RPM (idle speed). So if there was a problem with weak or intermittent trigger signal it would occur when trying to start the quad, not when it was running.

Ditto with the AC power from the stator to your CDI (if your CDI is AC powered). It should work better at higher speeds and be more marginal at cranking speeds when trying to start up.

CDIs put more power into the ignition circuitry at high RPMs compared to low RPMs. So if ignition coil breakdown was a problem it would be at WOT, not midrange.

So what about hooking a timing light up to the quad? You could shine the timing light down through the access plug on the side cover to strobe the flywheel marks. Do you se any difference between a working quad and the problem one. It is another data point to ponder.

 

Yeah, I agree about the stator and pick/up coil.
I am going to change the ignition coil tomorrow.

Really, it acts like a bad carb. But I can't for the life of me figure out how?
I took the carb that didn't run and the intake and put it on the other 150 and it ran great! This carb is a 27mm, not the 30mm. I am at a point of putting it together and placing it out for sale with a disclaimer that it needs carb work.

 

OK, I put a timing light on it, but this does not make sense to me. The timing mark is way lower than the mark it should be at. Checked at fast idle. The timing is spot on though. The crank is Top Dead center with the mark on the line and the cam gear in the right position.

Is there a way to adjust the timing advance?

 

There is no way to adjust the ignition timing. It should be correct, and if it isn't something is very wrong. I remember a post some time back about a 110cc quad with very wrong ignition timing which was caused by a missing ground wire. So it is something to check when having weird problems, but it is a long shot at best.

The ignition timing advance is set by design (pickup coil magnet strength versus pickup coil # of turns, versus gap to raised bump on flywheel).

What is meant by "way lower than the mark it should be at"? How does it compare to a working quad?

 

The problem with your bike is you not the bike,you are makeing a mtn. out of a mole hill,first make sure you have the original parts,stop changeing parts.Now ck. plug if fould clean .Turn air scwe all the way in ,back it back out 1.5 to 2.5 turns.If you wont to save your self some money,have someone to ck. your bike out that knows what he is doing,if you are not a mechanic you are going to do more damage than good,I am not trying to be a smart elec,but that is the best advise for you,good luck

 

They are chinese bikes what can you exepect.