Runs great, then won't start. Need a lil help

[jrm03]

Today was the first real extended ride I have had on the new motor. My quad will run like a raped ape, top notch, then after a little while of riding, when slowing down to a slow pace through trails or going down a hill. The motor will start to idle way down and cut out and then stall. I am thinking my jetting is a bit lean, which would cause excess heat. After you leave it sit for a few minutes, it will start up and go along on its merry way for awhile longer, then the same thing. Any opinions or past experiences like this? Is it possible for the heat to vapor lock the fuel line. I cut part of the breather hose and it is clear.

[jrm03]

anybody?

[zrpilot]

how is it jetted? what carb?

[Eviltanker]

Need more info to tell if it's carb or engine. Do you get any backfire (through carb or exhaust?) do you have any work done to the quad? Drive in a lot of water or mud? there is a few different things that could be causing this.

[jrm03]

416 +7mm stroke. race port and polish. HC Stage 2. Timing advance. Uni. HMF Full 165main 52pilot/leak(whichever) third notch down on the needle.
I am running a 450R carb. The motor was running a bit hot I am going to try a little richer mixture and maybe a higher main. Would this be symptoms of overheating or maybe vapor lock?
I will get a little pop from time to time on deceleration when the engine is holding the quad back.

[Eviltanker]

Richen up your pilot and go down one clip on the needle. this will richen your bottom and middle. The pop on decel is going to happen from time to time nothing to worry about.Also go up 1 or 2 on the main. It sounds like your lean, You are right. Is your lid on?If not and you don't want to run one then deffinatly jet up.

[400excaleb]

mine did the same thing, it was the stator. when it dies check for spark

[400exrider707]

I would ditch the timing advance, that is only going to make it run hotter. This is only recommended for un-modded motors.

[jrm03]

The lid is on, and after it happened the first time I went back to the truck and taped up the holes in the airbox. Still did it afterwards so apparently too lean. I will have to research the 450 carb and see how t o adjust the mixture and change the main. I know nothing of it, unless it is like the stock carb. At idle it heats up pretty quick, probably too quick, I can't really remember how hot my stocker got and how fast. As for the sparks key, that is on the list of things to remove. It was in there when I bought it and the previous owner had no problems with any of this. He was using a Sparks full system, and I am using an HMF, which goes to show HMF has the edge on flow.

[RiderTRX400ex]

my 02 started dieing after just a minute or two of idleing. thought it was the carb but it turned out to be a very dirty/gummy fuel petcock. just throwin you ideas!

[jrm03]

That is a possibility. I am only able to get fuel on the reserve setting. I only have a trickle of fuel when the valve is on the on position. It needs to be addressed, just don't know if that is the sole cause for having to leave it sit for a few then it will start??...

[ryanp]

i had a similar problem when I changed out my fuel hose...I cut it too short so it had a kink in it. Started up fine and ran great untill I got on it....then it would die when I let off the gas. Found out it was draining the bowl faster than the kinked fuel line could supply the fuel. Let it sit for a minute and she would start right back up like nothing was wrong. Got a longer fuel line and problem solved! Hope that helps.

[jrm03]

I put a tie around my line to the frame just now I did notice it had a very slight upwards bend. Thanks for all of the pointers. Keep them coming. My jetting is going to have to wait until I am able to get out and do a little testing. The joy of living in town.