Engine Trouble Engine dies at idle once warmed up.

that is strange, but there are intake & exhaust mods in the mix - #80 was specific to running WOT, so might throw everything off down lower

At .075 I still couldn't get WOT, but at .080 I could and it ran great, but I might be able to come down to .079 or .078 but can't imagine that small chance making much difference down lower...idk.
 
If it runs great accept for the idle the choke is a unlikely cause. The needle is more likely, but I think he would have thought of that having done so much jet work.
Having to run a #80 jet on a nt is unusually rich. Did it idle very high when it was jetted at around #70? I could be off on this, but my thinking is a small air leak could be corrected with jetting explaining the need for a #80. If the leak were in the intake and corrected through jetting it would most likely run good through it's entire range, but if it were at the crank seal at higher rpm it may run fine while at low rpm case pressure may not be high enough to deliver a good charge and die.
So the needle height if not yet addressed is the starting place. Move the clip all the way to the top and see if this helps.
I still think their is a problem some where causing the need for a #80, but if I'm wrong you might want to run a little hotter plug NGK b6hs
It wouldn't hurt to look for a possible intake leak and a look at the crank seals, especially the one behind the rotor to see if it's pushed out a little. They should be flush to the case.

Thanks. Will check on this stuff...when it stops raining!
 
Have you ever seen a new engine need to use a #80 jet with a nt carb. to run right? Sounds like something else besides the needle is off.
No! There is deffinatly an air leak at carb or intake normaly a #70 jet in the NT would be rich even with the pipe and intake changes.
 
No! There is deffinatly an air leak at carb or intake normaly a #70 jet in the NT would be rich even with the pipe and intake changes.
That makes sense. Will get it warmed up tomorrow and ask my wife to hold throttle to keep it running while spraying mist of water all over the place. Any better ideas to determine where leak might be coming from?
 
That makes sense. Will get it warmed up tomorrow and ask my wife to hold throttle to keep it running while spraying mist of water all over the place. Any better ideas to determine where leak might be coming from?
I would spray around carb and intake connections and also the case half gasket and base of cylinder.Is there an o ring between the carb and intake?
 
No! There is deffinatly an air leak at carb or intake normaly a #70 jet in the NT would be rich even with the pipe and intake changes.
I'm still leaning toward the crank seal. Tell me if my thinking is off. It seems that if the over jetting made it run good by correcting a intake leak it would be corrected as well at idle, but if it corrected the crank seal leak it could run good when high rpm gives enough crank pressure for the charge and at low rpm (idle) the pressure would be to low to provide a decent charge and die. I could be over thinking it.
 
I'm still leaning toward the crank seal. Tell me if my thinking is off. It seems that if the over jetting made it run good by correcting a intake leak it would be corrected as well at idle, but if it corrected the crank seal leak it could run good when high rpm gives enough crank pressure for the charge and at low rpm (idle) the pressure would be to low to provide a decent charge and die. I could be over thinking it.
I find when crank seals go and jetted properly the idle isnt as affected as much as the upper end,The over jetting allows for closer to ideal a/f mix in the top end but then is still lean in the bottom where the needle is restricting flow and not metered properly,this is also what occures when the case half gasket has a leak,but it also changes depending on how bad the leak is so it could be etheir I guess.
 
I would spray around carb and intake connections and also the case half gasket and base of cylinder.Is there an o ring between the carb and intake?
No o-ring at carb but have sprayed around that to no avail. Where would you put an o-ring with stock intake and NT carb? There's no groove for the o-ring to sit in that I see. How are you guys doing that?

Half gasket and base of cylinder...got it. I've made sure those screws are all tight more than once, but will check again and spray. Thanks.
 
No o-ring at carb but have sprayed around that to no avail. Where would you put an o-ring with stock intake and NT carb? There's no groove for the o-ring to sit in that I see. How are you guys doing that?

Half gasket and base of cylinder...got it. I've made sure those screws are all tight more than once, but will check again and spray. Thanks.
There's no groove it just sits between the end of the intake and the seat of the carb.
 
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