Gy6 will not start!
 

Hey guys,
I have a helix buggy with a gy6 engine. Today i swapped out the old carb for a brand new one, the old one had been left full of stinky old gas from the previous owner. I connected everything up to its proper place (i think). I have checked the spark plug and it fires, fuel is definitely getting to the carb. I can crank and crank and it wont try to start or even sputter. I even shot a little fuel directly into the cylinder, still no luck. What am i missing! Fuel+Air+Spark should= fire! Any helpful suggestions or insight? Thanks.

first check to see if the black plastic intake manifold is fitting tight down on top of the engine. Make sure the opposite end is snugly tightened around the carb. If you had to make adjustments for any reason to these areas then try starting the engine.

If it's not firing up then:
Remove the air filter tube from the carb, cover the opening with your hand, and have someone turn the ignition key while holding your hand over the carb. If it starts now you may have a low compression issue. Can you feel any suction on your hand when the engine cranks over?

Also, your carb has an electric choke that has an electrical connector wire coming off it. Did you plug it back into the harness?

Thanks for the tips gy6buggy88!
I did remove the intake manifold earlier to see if it was cracked or anything. The harness for the electric choke is plugged in. I had my daughter crank it while i had my hand over the intake on the carb. I could feel it sucking on my hand pretty good and fuel was definitely there. It makes a pretty good thump like a four stroke should when its turning over. Any other ideas? Thanks!

valve lash would be next item followed by timing if you're getting all 3 ingredients

I was really hoping it would be something easy! I thought maybe i had just missed something small. How do you check timing on one of these?

First of all I would really like to thank everyone who has taken the time to help me out on this one.

Ok. So, lucky for me, i had already removed my seats and seat belts a couple of days ago. I pulled the valve cover and the lash looks pretty good, around .015 to .020. Im not really sure how to check the timing on this machine, but the chain does look good and tight. Any suggestions? Thanks guys.

I adjusted the valve lash to .005 on both valves, still no start. Here are some pics of my carb, hopefully one of you guys will see something i did wrong. Thanks for looking.

Yep, remove the hose coming off the head cover from that "T", that's a vent to atmosphere.

Just mount the hose on the carb directly to the intake manifold. Only use the "T" if you have a vacuum operated fuel petcock

the old adage of a pictures speaks a thousand words. like xlint said. you're "losing"your carb's vacuum signal from the intake manifold by having the engine vent connected.

And a lot of times buggies wont run good without the airbox.

Thanks for the info!
I will definately give that a shot. I really appreciate all of your help and input.
I will post my results here in a little while. Thanks again!

I fixed the hoses like you all said, and now it really wants to start. It actually started for a hot second while i was pumping the gas pedal. I think i need to adjust the fuel enrichment, and let more fuel in. Do any of you know how to adjust the fuel on these carbs? Thank you all for your help. One step closer to running!

The fuel enrichment is electric. As the engine runs, a small plunger like device warms up and pushes out. That then closes off the enrichment orifice shutting off the extra fuel needed for a cold engine.

As long as you hooked up the electric connector and everything is working properly, that shouldn't be an issue.

You may need to adjust your idle air mixture screw on the carb. Try setting it at 1 to 1 1/2 turns OUT from a lightly seated position. (turn the screw IN until it just stops, then back it OUT 1 full turn)

Pretty sure i know the answer to this already, but do you know what size jets are in the new carb VS. the old one? You may need to rejet the new carb.

Im not sure about the jets, its just a stock carb for the gy6. I will try the fuel air screw though. Is that the one on the left forward side? There is also a screw on the fuel bowl. Im not too good with carbs, but i am willing to give it a shot. I am close to getting this thing started, I can feel it! Thanks for all of the info.

Alright, i ran the fuel air mixture screw all the way in then backed it out 1 full turn. Still no start. Backed it out another half a turn still no start. I even tried shooting starting fluid into the carb, it kind of bogs down for a second then It acts like it wants to start, it just cant quite get there. Any other suggestions? Thanks.

If squirting gas in the carb bogs it down then you are squirting way too much gas.

Thanks for the reply. I dont think i shot too much starting fluid into the carb, its more like a fog than a squirt. It also bogs down a little when i press the gas pedal down while trying to start it. I also tried adjusting the fuel screw while turning the engine over to see if i could find a sweet spot. No such luck. It still wants to start, but just cant quite get there.

If it's not firing with starter fluid then something is way off. Are you positive you're getting good spark? Is it an old plug? Is the plug wire maybe shorting out?

I tried a new plug and a new coil and wire. When i hold the plug up to a ground on the frame, the spark jumps a good 1/4 of an inch. Im about to take it to the shop where someone who knows more than me can try to figure it out. I really wanted the satisfaction of figuring it out myself (and its cheaper that way). Im still open to suggestions to try before i take it somewhere though. Thanks.

I don't know man, if you got spark and starter fluid it should at least run a little. If it were me I would do a compression check.

Remove your spark plug. Connect the plug wire back onto the plug, rest the plug on the engine so the electrode ( the little bent metal tab on the threaded end of the plug) is touching a metallic part of the engine. Have someone turn the ignition key to turn over the engine. Now you should see the spark arcing. If the spark is orange it's weak. If it's blue then it's strong. Make sure the sparkplug is "gapped" correctly.

The stock plugs that come with these buggys are garbage. Replace with an NGK or Champion plug. If you replace the coil buy an orange performance type.

GY6 spark plugs
The NGK standard plug can be found easily and they are cheap

NGK CR7HS standard plug, gapped at
0.024"-0.028"

OK, so if your carb plumbing is right, you have spark, then you need compression.

There are a couple things that still concern me.

1. Your valve clearances should be about .003 or .004 for the intake valve. You should be about .005 for the exhaust valve. (.015 is too much clearance)

2. You really need to go on Youtube and view a video on how to check the timing of the engine and camshaft. Then verify yours is correct.

3. if you have fuel and you have spark, do you have compression? (improper valve timing can cause problems)


The cheap carbs are not always ready to go out of the box. You may need to install different size jets and possibly check the float level. They are made in china normally geared towards the scooters, not buggies.

Be sure you got a nice fully charged battery too.