spark plug came loose

[macgillivary]

I was ripping down a road today 6th gear wide open hanging her out pretty good

bike was running really well

then all of a sudden it went from a BAAAAH BAH BAAAAH to a BLAH BLAH BLAH

it sounded and felt exactly the same as the time i blew a piston

so i feared the worst and was pissed, then i looked and noticed my left spark plug had completely came out of my head and was just hanging there on the coil

i put it back in, bike fired right back up and was fine for the rest of the day

now my question is ive heard that modquad heads are notorious for plugs coming loose, but wouldnt it be more less the domes fault since its the dome that the plug actually screws into?

and what would cause a plug to come loose like this? im only running 21cc domes so it shouldnt of been the compression to make it come loose

or does this kinda just happen every now and then when you dont check to see if the plugs are tight before you take off

thanks

[Shee-Male]

Maybee it wasn't tight in the first place?, do you run anti-size on the plug threads?

If that cyl was a little leaner it could run hotter and expanded more to loosen the plug? could be a few things who knows?

If it dose it more freaqently then start trying to figure out why.

[macgillivary]

its never done it before which confused the hell outta me

and ive had the head for over a year now with lots of ride time on it

plugs looked fine color nothing wrong, and i run a 2 into 1 carb so both cylinders should be equal

seemed strange

[odaen]

detonation can cause plugs to work loose.

[DIRTMAN350]

I've heard the horror stories about plugs coming loose and bought a billet plug lock which also works good for a spark plug wrench when i need it. I bought it from trinity racing.

[macgillivary]

damn detonation

i didnt wanna see that word come up

im running 21cc domes and +4 timing on 91, its real close

when a bike detonates shouldnt it get really really hot though?

my bike was running nice and cool 130-160 all day

[Ducman]

Usually cause by very high compression or detonation, but I've had a lot of plugs start comming loose after installing them new for the first time. After I retighten the plugs after the first use they dont seem to come loose anymore.

[eehsnab2]

what kinds of mods are done?

[macgillivary]

mods im running

fmf gold series pipes, modquad head with 21cc domes, mild port, ported stock reed cages, motofast 2 into 1 carb wth 40mm lectron, +4 timing, lightened flywheel, K&N

[rocketboy]

look at your plugs for gray specks or a grayish look to them

[macgillivary]

would grayish indicate detonation?

[thecabinboy]

My old set up had this happen a few times (once while shooting a big bowl at Glamis). Mine was caused by very high compression 215 at sea level.