I have a .15 o.s cv-x max engine and it is tuned properly but it wont idle for more than 10 seconds when i start to play with it. If i were to let it sit there it will idle for a whole tank of gas but as soon as i start to rev it up a couple of times it will shut off. my friend (expert) has been in the world of rc's way longer than me and he keeps on saying that it has something to do with the clutch. He says that there is a spring that i need to buy for the clutch. is this true and can somebody tell me if it has something to do with the clutch.

Is the motor revving high at idle?

it sounds like you have a low end needle problem try setting up the low end also put the plug out and see it its wet or dry good ck

it does sound like your clutch MIGHT be dragging and your brake is applied at the neutral position.
beyond that, you're either running rich or lean on the LSN.

get your engine warmed up and pinch the fuel line at the carb to block the fuel... if the LSN is set right it should rev up slightly for about 2 to 3 seconds and die.. if it revs really high for more than 6 to 10 seconds and dies your lsn is rich..

I would make sure your LSN settings are right before you go tinkering with the clutch.. If the LSN is good then start by checking the internals of the clutch, see if there is any drag, check the bearings.. if they are shot they will heat up and expand and can bog your engine..

I dont wanna sound like i'm Slow but i've never heard an LSN. By that you do mean the low end needle the high end needle and the idle screw right? anyway i think all my settings are correct because i've taken it down to a hobby store and they tuned it correctly for me.(that was when it was running correctly, and i haven't messed with the settings since. So if the bearings are just messed up then that could be the problem. What about the spring i told you guys about. Does that have anything to do with it. Oh and what do you mean by the drag. I've been in the sport for about 1 year and havent had any problems with it so just refresh my memory.

The LSN is the Low Speed Needle.. You should try the pinch test anyway it could save you a lot of time... Besides Hobby shops are notorious for bad tuning .. Ok Drag as it was mentioned will have to do with how the clutch bell rolls freely and indipendantly from the clutch shoes inside.. just roll your car along and notice if the clutch bell rolls freely without making the flywheel turn.. the flywheel is the thing that the clutch bell is attached to.. If it makes the flywheel turn as well you have a problem.. You may also have an airleak in one of your fuel lines.. is the carb bolted down well to the engine .. ie any movement when you try to twist or juggle the carb ?

well the flywheel doesn't move while pushing the car along the gorund and the carb is set in pretty tight. And i also have brand new fuel line that i just now bought. So what else could it be, The LSN? What settings should it be at?

The flywheel doesn't move????

Are the brakes Locked on while the servo's is in neutral?

Have you taken of the clutch bell to have a look at the springs?.
Try changing the springs if they are there as maybe they have no tension anymore

Heck, sounds like his flywheel isn't pressed onto the collet.

I explained how to tune it in the previous post ..

oops...misunderstood...WHILE the car is rolling.
nevermind.