what is the correct spark plug gap for a 400EX?

[Chef]

what should i gap my plug at for my 440 with the mods listed below? and one other thing, if i am riding hard, and then i slow down to an idle about, the motor dies, any ideas? and if i dont have alot of RPM, just lugging it the slightest bit, the motor sputters and doesnt want to run, it usually happens in 3rd and 4th, any ideas? im running without the air box lid or snorkel.

.24 to .28

[400grl]

You have a screw that will adjust your idle speed - sounds like you need to adjust that a little - make your idle faster. I don't have my manual in front of me, so I can't remember exactly what it's called! It also sounds like you may need to change your jet. Your motor isn't getting enough of something!

[Chef]

actually now that i think about it, may just be loading up. i know its a four stroke and all, but that could be whats happening, and i checked the plug, its a nice golden brown. so it may be just loading up. i hope that its a simple problem like that. ill adjust the idle today when i ride.

[Leo]

motors with very aggresive cams don't like to idle..

if the camshaft has a lot of overlap it allows the exhaust gas to slightly dillute the mixture, which is a good thing at high RPM (reduces the likelyhood of pre-ignition) but makes a low idle speed tough to achieve.. Aggresive cams also effect engin vacum at low RPMS, so it may be a jetting problem?

Just think about the local hot-rod with an aggresive cam and how they 'lope' at low RPMS..

Leo

[Chef]

thanx leo, and i know what you mean about the local hot rod, we own it. and now that i think about it, when we slow down at like a stop down, it occasionally dies just like this does, so i think i just need to run it a little harder to keep it cleaned out. the rod is a 1967 nova pro street car, atleast thats what i think thats the class it is in. Its got a 600 horse 358 with the vortec heads and a "hydraulic roller" camshaft in it, the cam and rockers were like $3000 alone. and a 200 shot of nos for whenever we have room, and when we have the guts. :devil