150cc gy6 engine sputters and bogs down

[buggydad]

Hey guys, just bought a brand new buggy for my kids for Christams. BMS King Cobra 150cc. Went together great. Started right up but sputters under load and bogs down a bit. When it doesn't, it takes forever to get to top speed and engine still seems to miss. Any ideas??

[metalstudman1]

Contact the dealer

[buggydad]

Bought it over the internet. I have contacted them. I believe they will replace the Carb but I was wondering if anyone had any advise before I did that. I want to have it going for Christmas. It's a present for my three kids. If there is an adjustment I could make I would rather do that than wait on new part.

Someone told me there is an air adjustment screw that is capped when it comes from the factory. He told me to pop cap and try adjusting the screw. Does that make sense. Also tole me to check Carb for crap in the jets. As well as air intakes.

Thanks for the reply.

Buggydad

[metalstudman1]

Since I don't know what your warranty requirements are, and if their willing to send out another carb- then "Yes" there is a cap that covers the fuel/air screw.without seeing your carb- it's usually on the drivers side closer to the intake of the carb.There's a link on here that Buggymaster posted somewhere!What elevation do you live?Chances are that it's the jet is the wrong size.

[buggydad]

I live at about 520 feet above sea level. The guy at the dealer is the one who told me to take carb apart check jets, check air intakes. Then he said to pop cover off air screw and turn to 0 then turn back to where it was plus half turn. I asked him if all this doesn't work, will they send new one and he said they would. That's where I am.

[metalstudman1]

Go ahead and remove the carb. un-screw the bowl and see if there's a blockage and check to see if you can see the numbers on the jet

[ckau]

I would be very careful about making any adjustments to this buggy yet. you wouldn't want to do anything that the drop shipper could claim as a warranty violation. Dropping the carb bowl to look for trash would be OK but anything further might give them an out. You already contacted the dealer and he didn't blow you off so that is a good sign but I'll bet he doesn't have a clue as to what the problem is. I don't mean to sound like a pessimist with your dealer but the list of folks that have been burned by internet buys is huge!


I would do this first, these are a some of the most common problems found.
Inspect plug for color. black or white? this will give your best indication of whats going on.
Inspect the tank, fuel line and filter for good flow. finding a filter installed back wards is not uncommon.
Drop the carb bowl and inspect for trash. not unusual to find bits of plastic and all sorts of stuff left behind during initial assembly.
Inspect All wiring connections. A bad connection can give all sorts of trouble.

Keep the forum up to date and ask questions There are some extremely knowledgeable people here. They will get you straight.

[buggydad]

thanks, I will check the jets from the bottom of the bowl. I checked electrical and as far as I can see all connection are tight. I checked the vac lines and they are all connected. I did check the the side diaphram on the side and top and both looked good. I did not look at the jets because I did not take the carb off the engine. I guess I will do that first and see what it looks like from the bottom.

Thanks for your help.

[buggydad]

carb jets numbers. small one is 35 and the big one is 95. Does that sound right.

Idles fine. I have to coax it through low to medium and then it runs fine. Has no top end at all. Jets are clean. Diaphams look good. Auto choke is extending about 2 16th.

Plug was black as coal.

Does not run well with air box opened up.

Any suggestions. I think I am down to rejetting but would I have trouble in low and high with the jets I have?

Please help.

[SYCARMS]

The #35 jet would be the pilot (idle) jet, the 90 would be the main jet. The smallest I have ever seen in the 150 gy6 engine is a 108. Everyone is having problems bringing in the 150 & 250 engines due to passing epa. The 90 is way too small, Tom

[riggen127]

I just bought two of the BMS King Cobra 150s for my boys for Christmas. The first buggy runs great but the second buggy is doing the exact same thing as yours. Please let me know if you solve the problem. As I hope to have it running for Christmas.

[buggydad]

Did you check the fuel filter inside of gas tank for crap from factory?

[buggydad]

Tom, if I switch to a uni filter what size jet would you suggest?

[riggen127]

I ended up finding the issue... pulled the spark plug and realized that it was running lean. Poped the cap off the fuel air mixture and adjusted. Buggy runs great now. I did pull the jets and found that I also have a 95. I plan on changing this.

[buggydad]

What rpm reading are you getting on the tac? Were you bogging down at higher speeds only? Man if it's that simple I'm on it I was just worried to pop cap and void warranty on carb.

[buggydad]

Are you running 93 octane? My engine plate calls for that? Can you get to that screw while the carb is on the engine?

[SYCARMS]

Originally Posted by buggydad

Tom, if I switch to a uni filter what size jet would you suggest?

125 main jet
Tom

[metalstudman1]

Yes you can remove cap and adjust while on the motor.You'll need to have the buggy elevated for testing.Pay attention to the original location of the screw and only turn in 1/4 increments to start with. I've found that this screw is for fine tuning only and doesn't make dramtic changes. My reference point should you lose track of the original position is 1-1/4 turns out.I suggest fine tuning with the aircleaner on.

[buggydad]

Ok the 120 jet did not work. I couldn't get it to run as good as it runs with the 95. Couldn't even get it to move with that jet. I just swapped it at the store for a 105. I will try that in the AM and see what happens.

I have checked all connections but I have not tried a new coil or spark plug wire. It is the only other thing I could think of if the jet doesn't work. I think I am running out of things to try other than a new carb. Looks like that will be the way I go if new jet in carb does not work.

buggyman1

[buggydad]

Thought I had checked the slide earlier but just happened to check it again today and it is not going up to the top. Could explain the black plug, running rich, and the lack of top end. I am going to pull it out and check it again. See if it is sliding ok or if it bound up. If it sliding ok I guess it would be a vac problem or a diaphram leak.

[airtime]

i just got a used 2009 helix 150 also. mine cranks and idles fine and midrange seems good but the top end feels flat. i don;t think this thing will do anywhere near 40 mph. it is a christmas present for my 12 son so i have not been able to test it yet. i will tomorrow. just wondering on the slide not going to the top. i will check it and let u know back. i will also check my main jet and see what it is for you also.

[KID4LIFE]

airtime,
i just picked up a 2009 carbide for my boys and i believe these have a restricted CDI in them that keeps the rpm's from going too high. i just replaced my stock CDI with a performance CDI and i can hit top end a lot better now. i also got some lighter rollers, a stiffer main spring, a unifilter and put in a 125 main jet. it runs much better now.

[BuggyMaster]

Airetime, is the machine brand new?

[olderthan]

all new buggies are running lean from the factory due to epa stds. change jets adjust
fuel/air screws switch to uni-filters check with your supplier to make sure ok under
warranty-used to be 108 was smallest jet in 150cc-now lots smaller

[SYCARMS]

And I'll add to prior posts. I had just done some warranty work for a customer on his carbide. Besides the tranny messing up, when I test drove it, it seemed to run fine but would only go 25mph. I put a performance cdi in it and it would go 32mph than you could tell it was starving for fuel. When I pulled the bowl to check the jets the main jet was only a 95. This is why the cdi has such a low rev limit.With the epa's mandate of fewer emmisions for 2012 I suspect the GY6 may be history in the not so distant future as well as the CN/CF 250. So if the cdi is changed out for a performance one make sure you rejet or you will certainly fry the engine.
Tom
Tom

[buggydad]

Got the slide working in carb. Put in a 105 jet and rpms are now up to close to 10k. Going to put a uni filter and a 120 in it next

Top speed
seams to be around 36. I think I should be able to get more top end out of it.

[olderthan]

sounds like you are getting the hang of it-run a gps on it then go to the uni and 120
& check again

[mzeblu]

I bought a used helix, I'm guessing it is about 3 years old.
Almost everything you guys are talking about is greek to me. I wish I could say I know my way around small engines but I dont. I am learning a lot just from reading these threads.

The one thing I wish that I could find is link list that would make purchasing these upgrades easier. Google searches for a 105 or 120 jet and a UNI filter yields billions of results as you could imagine. Maybe there is a sticky somewhere but I certainly haven't found it.

I'm confident that I might be hitting 25mph max and I want to do some mods to get it up to speed, I was thinking about rejeting it and putting a uni filter in for starters, I need to read up on the performance CDI that was mentioned.

If anyone who is buying these items and cares to post any links to the sites they bought them from, I would be forever grateful.

[metalstudman1]

Just go to the banner at the top of the page! http://www.sycpowersports.com/index.asp?mid=1
Tom has everything you need and all the answers to your questions-It doesn't get easiier than that.

[mzeblu]

I guess it was to late at night for me when looking at SYC website.
I believe I shouldn't have any problem now that I have discovered the magical drop down menu on their site, lol

[SYCARMS]

I plan on changing that up some in the near future. Give me a call for I have items not yet on the site. 662-301-1563 or e-mail me your number and I'll call you

Tom

[olderthan]

sycarms is a very good guy he has tried to help me on elec problems/solutions on my
roketa even though i have not bought parts from him yet.but i will sooner or later

[david]

[QUOTE=buggydad;11728]Ok the 120 jet did not work. I couldn't get it to run as good as it runs with the 95. Couldn't even get it to move with that jet. I just swapped it at the store for a 105. I will try that in the AM and see what happens.

I have checked all connections but I have not tried a new coil or spark plug wire. It is the only other thing I could think of if the jet doesn't work. I think I am running out of things to try other than a new carb. Looks like that will be the way I go if new jet in carb does not work.


david [suggestion]
while working on yerf dog carb found where air passage was drilled for electric choke drill had drilled to far causing an internal air leak-patched needle sized hole with epoxy runs and idles great now, just wish i had found it before i replaced all the electrical components-davids small engine repair

[MudRunner03]

My helix 150cc go cart runs smooth nothing wrong with it atm but i wanna kno what i should do to it.. i dont really go full range speed i just ride trails and mud bog.. that kinda thing.. if i were to change out the springs and coil would i have to changed out jets too? and wheres a good place to get these...

[SYCARMS]

One of the first mods you will want to do is to replace the current stock air box with a uni filter, as well as to open up the exhaust or replace. You will have to rejet the carb. I you like you can give me a call and discuss the engines performance then go from there. This will give a better feel for your location, terrain, driving needs, budget ect.I stock most everything you will need. You can contact me @ 662-301-1563

Tom