Helix Go Cart won't take throttle

[Pure_Michigan]

Hello everyone.  This is a Go Cart and not a typical "ATV" but it has an engine so I'm hoping someone can help me.  It's a Helix FTX with a Manco 150cc engine.  The engine will start and idle for awhile, but will not take even a small touch of throttle.  Stalls.  It seems to take throttle and rev up when you first start it cold, but in just a minute, it will not take any throttle.  I've replaced the Fuel valve/Pump on the fuel tank with no joy.  It's a nice little cart, but without a workable engine, it's a boat anchor.  I'm not dumb when it comes to small engines, but this one has me stumped.  I'm running out of options.  

I'll mention that while it is idling, it will sort of "cough" every 6 or 8 seconds and then recover and idle again.  Eventually one of those "coughs" causes it to stall.  It will start back up pretty easily, but as I said, it absolutely will not take any throttle and then it will cough and stall a minute later.  I thought it could be timing, but there is no "adjustment" for timing on this engine.  I downloaded the user manual and it mentions nothing about timing and is pretty much useless as a service guide.  It just shows the basics.  I'm attaching the manual so you can get an idea of the machine I'm dealing with.  

Any input would be greatly appreciated.

Kind regards, 

Don

 

Manco-Helix-6150-150cc-Owners-Manual.pdf

[Mech]

That one intermittent miss then going straight back to a steady idle again, that's a lean idle mixture. You could just try adjusting the idle mixture which might fix the misfire, but if it can't be coaxed to rev up, it probably has dirt in the carb, so I'd just pull the whole carb off, strip it entirely and clean every jet and drilling, check the float height then put it back on checking there are no splits or leaks in/at the manifold.

Edited October 25, 2024 by Mech

[Gwbarm]

Nice looking machine reminds me of the Honda Odyssey from the 80s. Did it just start doing this or has it started getting a little worse over time. 

[Pure_Michigan]

Reply #1.  I have also concluded that the carburetor is dirty.  I just got the go cart a couple weeks ago, it had been sitting outside for 3 years so this is the initial start up and run test.  Instead of trying to clean the carburetor with the chance that I won't get it cleaned good, I just ordered a new one.  For $25 I avoid the possible frustration.  It should arrive today.

Reply #2 As mentioned in reply #1, I just got this thing so it's been doing it the whole time.  I have a feeling the new carb will do the trick.

Thanks,

Don

[Mech]

Ok.  Hope that gets it running good. You'll probably need to adjust the new carb's idle mixture once it's warm.

[Gwbarm]

 Yes the carb definately needs cleaning or replacing but a 25.00 carb may be more frustrating than you think,i i know, but im not familiar with that engine so anything may run good on it. Whats on it now.

[Mech]

Gw's got an important point here.. Something we see quite often in here with the quads is that someone replaces a carb because they have a problem, but then the new carb doesn't stop the problem, and so they assume the problem isn't with the fuel mixture. They they go off on a tangent assuming it must be electrical or compression etc. Replacement carbs do quite often run badly because they aren't tuned for the engine they are going one. So then you need to go through a tuning and adjusting process to check whether it is the new carb not tuned, or a lack of compression, blocked exhaust or bad spark problem.

It is generally best (simplest) to clean the carb that came or had been running well on the bike.

Let us know if the bike doesn't run well Don. Apart from the idle mixture it may need some other adjustments.

Edited October 27, 2024 by Mech