Cutting out at half throttle!

[Mr. Minecraft]

Alright. So I took off the carb again and blew through the entire carb, cleaned the low speed jet with a small strand of metal I had, and put it all back together. The O-rings are all in good shape, and the gaskets are perfect.

After that I opened up the valve cover and re-gapped the valves to .004 .006 again (those have been the settings that worked on this bike in the past).

I started it up and it runs, but If I open up the throttle too fast it dies. This is most likely a tuning issue, but before I go mess with the runing screws, I want to get some info on the behaviors of these engines. For example, "If the engine bogs when opening the throttle, then it is too rich" etc.

Thanks in advanced for helping me through this little dilemma!
-Chris

 

[Bikeguy Joe]

If it bogs when you open the throttle too quickly, it's likely too LEAN.

 

[Mr. Minecraft]

Alright thanks, Ill go get to work on it.

PS: 200th post nothing compared to your 11k+ xD

 

[Bikeguy Joe]

Yeah, been here awhile

 

[Mr. Minecraft]

Alright so I got it tuned in. Still has some bog when going from idle to WOT, unlike my other bike that can handle it perfectly. Why would that be?

 

[Bikeguy Joe]

Maybe a bit lean still.

 

[Bikeguy Joe]

You could just be trying to feed too much throttle too quick too, or from too low an rpm.

 

[Mr. Minecraft]

Hmmm... Ill mess with it tomorrow. Tonight, I feast!

 

[GearNut]

My quick and dirty definition of an accelerator pump on a carburetor:
A device that adds a metered amount of fuel directly into the carburetor throat upon a quick movement of the throttle mechanism.
Reason: To overcome a lean condition that is caused when the throttle mechanism is opened so fast as to allow a large volume of air into the intake faster than the fuel circuits can keep up with. This is in an effort to combat engine hesitation or an all out stall due to not enough fuel being added to the incoming intake charge.

HuaSheng carburetors do not have an accelerator pump. A fast blip or twist and hold of the throttle from idle speed and you should expect the engine to at best- stumble, at worst- die.
No 2 engines are the same, no 2 carburetors are the same. Some will tolerate a fast throttle action better than others.

Raising the idle speed can help overcome this problem to a degree.

 

[Mr. Minecraft]

Its funny though because every goped and motor bike I have owned I could gas it straight from standstill to WOT without any hesitation. The gopeds did not have accelerator pumps, I used the carbs without them to save gas (like walbro 603 compared to the 813 with a pump). I guess its tolerable though, thanks for the help.

 

[Bikeguy Joe]

I would enrichen the low end a bit more.
I think I said that.

 

[Mr. Minecraft]

Yea you did, I was just adding some tidbits of information

 

[Mr. Minecraft]

Alright, well I have tried every needle setting imaginable and it still nearly dies when i give it more than 1/2 gas. Seems like a problem with the high speed jet, but the jet is clean so I cant figure it out...

 

[GearNut]

After re reading this thread for the umteenth time I did not see where you changed out the spark plug and yet you did ask which plug would be good.
Have you changed it out?
An excellent plug is an NGK CR7HIX iridium (#7544).
What color it your current spark plug?
Immediately after the engine acts up and it refuses to start is the spark plug dry or wet with fuel?

Considering that it ran fine before you cleaned everything I do not think that the fuel jet is too big now.

This is definitely a frustrating diagnosis.

 

[Bikeguy Joe]

Make sure fuel is flowing to the carb., and try a NEW plug. Doesn't need to be anything fancy, just a NEW one.

 

[Mr. Minecraft]

Alright, I will head down to my local auto store and see if they have any good quality plugs in.

 

[Mr. Minecraft]

Alright so I got the Iridium NGK plug that GearNut recommended, and the first thing I noticed was that the exhaust smells much cleaner and there is less white smoke. Second thing I noticed was that the bike has alto more torque than before. I could not ride for log though, so I don't know if the original problem is still there. I will find out tomorrow!

 

[ocho ninja]

Hmm white smoke? sounds like you have a much more serious problem. White smoke means your burning oil, and its not supposed to be doing that.

I have 40 hard hours on my HS and i never even seen a puff of smoke come from the exhaust.

EDIT:
Actually it sounds like the rings are no longer providing a good seal, thus causing oil to go into the combustion chamber and cause the white smoke.

 

[Mr. Minecraft]

The smoke was not like when a car burns oil (the thick, dense smoke). What i meant to say was there was less visible exhaust.

 

[ocho ninja]

I still think there shouldn't be any visible exhaust... as far as i know 4 stroke engines don't produce visible exhaust like 2 strokes

Is the visible exhaust constant even when your riding it?