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spark plugs falling out


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spark plugs backing out mean your detonating which means you VERY lean. and you need to upjet before you melt down the motor. what mods, jetting, elevation...etc

all mods are in my sig. jetting is 300 mains, 30 pilots, stock needle position, running 93 octane with 150 psi compression. the elevations is between 500 to 1000. plugs burning golden brown. its the 96.

Edited by twizted269
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what causes the plugs to back out? i locked them so tight i was worried about stipping the domes out. does anyone use locktite on them? im gonna get the bracket that holds them both but just wanted to know.

dont get the bracket,thats only housing a problem....plugs back out for a few resons.

1 detonation

2 damaged threads on domes

3 crank may be out of balance

Edited by tony cub
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dont get the bracket,thats only housing a problem....plugs back out for a few resons.

1 detonation

2 damaged threads on domes

3 crank may be out of balance

i was thinking maybe the threads also. crank only has about 4 tanks on it so i wouldnt think that. also it never did this with the stock head. only since the cool head was installed. maybe compression change? went up 40 psi

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i was thinking maybe the threads also. crank only has about 4 tanks on it so i wouldnt think that. also it never did this with the stock head. only since the cool head was installed. maybe compression change? went up 40 psi

whats your squish at??

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i was thinking maybe the threads also. crank only has about 4 tanks on it so i wouldnt think that. also it never did this with the stock head. only since the cool head was installed. maybe compression change? went up 40 psi

 

Whats your compression? Sounds like your detonating, need race gas in there.

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i havnt done a "plug chop". never have. allways went by the colot of the ceramic. i have no idea what the squish band is at either. i would asume stock with stock stroke crank and pistons. compression is a 150 psi which seems it should be fine for 93 octane. if not ill get another set of domes to lower it.

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i would definately say detonation.. what size domes?? what is your timing at?? start by throwing more fuel and less timing at it.. get it safe, then start tuning it from there... check those plugs..

dome are 20cc with +4 timing. looking to go with 22cc soon. working out the kinks from the winter build is getting on my nerves lately. lol.

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check and make sure all bases are covered.. make sure your flywheel key isn't sheared causing timing issues... i run 19cc domes and +5 timing on 93 pump gas no problems.. but im throwing a lot of fuel at it. my compression is about 160.. what plugs are you using??

im just running the standard br8es plug. what are the main causes for detonation? the only thing ive changed for this problem is the cool head. jetting was always pretty rich with the stock head. im pretty set on going to 22 cc domes and get it closer to stock compression. fly wheel key is also fine. checked that for another problem i had.

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You could've stripped the threads when you were tightening down on those plugs. Are you tightening them with a correct size socket. Or are turning them with a wrench? Have you checked the plugs since this started?

i use a wrench for the plugs. i changed them out on the trail today and they look golden brown.

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