Someone else with idling issues

[ecilop]

We bought a used Kazuma Coyote go cart with the gy6 150 for the grand kids. With info from this site we got it running. It starts easily and has plenty of power but I just can't get it to idle properly. It will idle for 5 to 10 seconds and then die, but will re-start easily. I can increase the idle using the idle screw but when I get to the point that it will stay running, the idle is too high and you can't shift from forward to reverse without shutting the engine off. I started the mixture screw at 1 1/2 turns and as I adjust it, it doesn't seem to make much difference. Using info from this site I have adjusted the valves, cleaned the air filter, new in-line fuel filter and cleaned the carb with no improvement. I put a new carb and new vacuum line on it, as well as a new intake manifold, still with no improvement. The FEV has power. Sorry to be so wordy but I wanted to try and list everything I have learned here and tried. Any suggestions would be appreciated. Thanks

[SLESTAK75]

Welcome title the site. Glad you were able to get her going. Try adjusting the idle up to where it will keep running and then try adjusting the mixture screw. Don't be afraid to try screwing it in more too. Adjust it to the highest idle. Then readjust your idle speed. Let us know howthat goes.

[xlint89]

Welcome to the site.

Are there any modifications done to the kart?

Is the air filter dirty?

Have you checked the jets in the new carb against the old carb?

Did you get the same size carb as the old one?

Usually if the idle mixture screw makes no difference, your pilot jetting is off. What size pilot is installed?

[ecilop]

Thank you for the quick responses.

Slestak 75: I have tried that numerous times with the same result. I can raise the idle up with the idle screw and adjust the mixture but it is almost like the mixture screw isn't having any affect with the idle that high.

xlint89: There are no mods. Although I don't know the year, it doesn't seem like it was run very much from the overall appearance of the kart, but I think it was run hard for a short time before they broke the reverse hear box. The original wrapping paper was still on the front A arms when we got it. The air filter is clean. I ordered the same carb that was previously on it. The pilot is 35 and the main is 95. What size should they be with no mods?

Thanks guys.

[SLESTAK75]

The pilot seems right, the main seems a bit small though. Might check for a vacuum leak next. With the engine running take a can of starter fluid and spray it (conservatively) around the intake and carb. If the engine revs up it has a leak somewhere. The intake has an o-ring for a seal. If this sat for some time that o-ring could be dry rotted and no longer sealing, or the intake could be cracked. Could also be as simple as vacuum lines not properly run.

[ecilop]

Thanks Slstak75. I previously have tested for that with negative results but I replaced the intake anyway. New O ring, spacer and gasket. The vacuum line is also new. When I raise the idle to keep it running it runs fine and has plenty of power, just can't get it to idle properly.

[Johnny 5]

Welcome to Buggymasters

I bought our red 2005 dune 150 not running and it had a leaking intake boot and would not idle after it warmed up without the idle set really high, replaced the intake boot and it improved but still would stumble off idle unless you would puch the gas to the floor.
It also ran pretty bad all the time.

I later found the intake valve was bent when I removed the head to port it.

This buggy was run hard and looked like it had rolled over because some of the roll bars were new with the stickers still on them. And it had a bucket with damaged parts in the front seat with a old engine on the floor board that died from lack of oil.

You could have a slightly bent valve from over revving from the last owner.

Just my experiance so far with idle issues.

[SLESTAK75]

Bent valve seems to very common. People love to run them very hard. Check compression would be next step.

[xlint89]

OK, jets sound about right for a stock engine.

Can you post a pic of the carb hose routing? Maybe something was ran wrong?

What spark plug are you using? And what's it gapped at?

Just for the heck of it, did you run a compression test?

Valve adjustment should also be checked if you haven't done so yet.

[xlint89]

Originally Posted by SLESTAK75

Bent valve seems to very common. People love to run them very hard.

Common on modified engines maybe. I would think the stock rev limiter should help prevent over revving. Aftermarket CDI with no rev limit would be very possible.

[SLESTAK75]

I got a hot coil but I am reluctant to put a no rev limit cdi on mine, just because I fear that I will jump on the blow it up bandwagon. That head I got at least comes with stiffer springs so maybe I can just get 90k rpms out of it. That should be good for 100mph right??????

[ecilop]

What a day. First, let me add that one of the things we fixed when we first got the kart was that the oil level was too high. It was in the cross hatch area of the dip stick but was blowing oil out of the valve cover vent tube into the air box. We drained the oil (which looked new) and put in the correct amount, which solved that problem. Having said that:
xlint89 - there is only one vacuum hose running from the intake nipple to the carb. The plug is a Torch A7RTC, is gapped at .028, and is burning clean. I have not run a compression check.

Today I pulled the plug to get that info and while I was there I pulled the valve cover and removed the vent hose from the air box to re-check the clearance. They were both still at .004 as previously set. I put the valve cover back on, plug back in, and fired it up. After it warmed up I backed the idle screw out to play with the mixture screw again and the darn thing kept idling! I tweeked the mixture screw, readjusted the idle screw and it idles perfectly. Then I noticed that I had not connected the valve cover vent tube back into the air box. I don't really understand this. The motor runs great (and now idles) and there is no smoke coming from the exhaust that would indicated to me the rings are bad. Anyone have any thoughts about that one?

[xlint89]

Is the vent tube fitting on the air box plugged up?

[ecilop]

No it is not clogged xlint89. The air intake hole in the airbox is not very large. It seems that the fumes coming through the hose into the air box at an idle were choking out the motor.

[SYCARMS]

The engine may have a bit of blowby so when you connect the vent to the airbox it sucks oil right into the carb which will act like a 2 cycle fuel mix. The EPA requires it to run to the airbox so that the oil fumes will be burned in the engine thus slowing the globe from warming and making the polar bears uncomfortably warm. I never understood why you would want to burn the oil residue vented from the crank case since oil does not burn completely and emits hydrocarbons which then melts the icecaps and makes Al Gore very angry, and we don't want to make him angry for he might pull the plug on the internet he invented and that would be the end of this forum. We would then all have to get 3 way or confrence calling to talk to one another at once

[ecilop]

I think at this point I will take my chances with the polar bears and zip tie the vent hose to the frame.

[SYCARMS]

Thats what I would do. They do this on cars but with the use of a PCV valve which does not allow oil to be sucked in to the carb. You should run a compression test on the engine then you will know where you are.

[ecilop]

I will try and get a compression tester and get that done soon. I appreciate all of the input everyone has given me with this problem to get it resolved. Thanks!

[ecilop]

I may be a gluten for punishment but; now that I have the idle issue fixed, would you guys recommend that I get rid of the factory air box and filter and go with something like a Uni filter on the kart, or should I leave it alone?

[SYCARMS]

Yes, Yes. That is yes for 2 reasons. The first is the most obvious, restriction. The UNI will let the engine breath better but you will also have to rejet the carb for you will deffinately be runnung lean and open up the rear of muffler to about 1". Now you don't want to gut it but just enlarge the 1/2" tail opening to 1". Second the air box currently on it , if not already leaking will eventually start by sucking air around the filter. This is where you wear out the rings.

[ecilop]

Thanks for the input Sycarms. The muffler opening at the end is 2 1/4 inches so I assume that would not be an issue. What size jets would you recommend with a uni filter or is that a trial and error issue?

[SLESTAK75]

Not to mention that you will get better performance. I just want to make sure that when you say you are going to zip tie the vent to the frame you are not closing it off. You may want to look into some sort of oil catch system for the vent. Mine will flat SPRAY oil all over the place when I'm on the throttle so I am currently trying to come up with some way to catch the oil while still letting the gases escape.

[ecilop]

Thanks Slestak75. My intention isn't to close it off. I just want to point it down and zip tie in in place to keep it from flopping around and getting somewhere it is not suppose to be. If I don't, I'm sure it will. After I replace the air box, I may try putting a piece of the stock air filter media over the end of the hose to keep debris out and still let it breath. Does someone make a filter specifically for that?

[SYCARMS]

You would want to rejet to a 125 main. I don't know of a filter for the vent. I had tried a few from auto zone but keep loosing them. I went with the oil catch can on mine since I am running so much compression. These cans have a oneway valve to eliminate sucking in of debris. I don't however feel you will need one providing you have a good ring seal on a stock engine with the factory compression. You can tiewrap a piece of terry cloth or scotch bright over the end of the hose but you will have to inspect ocasionally to make sure it does not restrict. The cans do look better then the later but for a quality one your talking around $60.00.

[ecilop]

Hey Tom. Just wanted to let you know I got the package yesterday and I will put everything together this afternoon. I will let you know how it comes out. Thanks for the info and the quick service.

[SYCARMS]

My pleasure,

[ecilop]

Just wanted to give everyone an update. I got the stock air box removed and the new jet and Uni filter installed. I tuned the carb adjustments and the cart idles and runs great! My thanks to Tom for the parts and to everyone here that helped me with suggestions to get this thing running properly for my grand kids. They love it.

[SYCARMS]

That makes it all the more worth while watching the grandkids have fun.

[Johnny 5]

What size jet did you run and what was the stock one?

For some reason both our buggies like the smaler jets.

[SYCARMS]

I sold him a 125 jet. You may run smaller since humidity is lower in CA. But when checking the plug it must be done either with a meter at wot or wot run with no idle time what so ever. Many will check their plugs after a ride and think there ok since they read brown, but the reading is a false one since it incorporates idle circuit as well, which gives a whole different reading. In cars that is fine to check that way but in these buggies the pedal hits the metal much more often and stays there at max throttle. That is where you get a lean mix which can do damage to the engine. I've have had people tell me there mix was great, dark brown then one day the engine locks up due to a full throttle lean out that melted the piston. As I said you need either a machine or you do it the redneck way which is to run full throttle for 900-1200 ft. and while still at full throttle cut the engine. Only when the engine kills do you release from full throttle. Immediately pull the plug and read the color. This gives a 98% accurate reading.

[ecilop]

What SYCARMS said Johnny 5. The stock jet was 95. When I installed the filter I added a 6 inch extension tube (redneck intake) and made a simple bracket from the stock air box bracket to the tube for support. Everything just fell in to place. It was almost too easy.

[SYCARMS]

It was almost too easy because Murphy was screwing with someone else, but who? Stay tunned to this forum to find out!

[SLESTAK75]

My jet size is ................. Wait for it...............747 waka waka waka.

[Miamieddie]

Always remember before removing y'all spark plugs wait for motor to cool so you don't screw up ur threads...Eddie.