Shorter than factory recommendation will make you detonate. Always check your gap when installing new plugs.

Loose plugs will lead to overheating and detonation.

I spoke to Ike over Advent and asked him why after market ignitions companies always recommended opening the gap of the plugs when using their ignitions but Advent had no info on it. He told me that we could open up the spark probably all the way to .050 since the spark intensity is 3x the stock one.
Has anyone tested different gaps with the advent??? There has to be an optimal gap for it. Remember if you open up the gap also open up your high speed adjustors. DO NOT GAP SMALLER THAN FACTORY RECOMMENDATION.

[ 01-10-2002: Message edited by: Fercho ]

i was up near the 50 area....lost some top rpms....near to the stock setting was best.

Hop did you apen up your highs.
Did you test .045-.047-.048

Fercho, since the spark plugs are different on a stageII, (different head) what is the the correct factory setting for the different plugs? rpfossil

RP as far as I know they are the same plugs
BR8ES-11. @.043. What different plugs are you taking about???

http://www.nightrider.com/biketech/tech_spark_plug_gap.htm

[ 01-10-2002: Message edited by: Fercho ]

46, 48 & 50....did not adjust high screws for the diff. gaps.

Fercho, what about running the BR9ES plugs. One step colder. The 8's are too hot with high compression and aftermarket ignition according to NGK. Anyone tried these yet?

Hop I understand if you open up your gap and you get a longer strong park you lean out the ski. So you will need to open up the highs to burn more fuel.

Todd When I tuned my ski for peak RPM and did a plug reading, the color was light chocolate brown. Just perfect. If I was getting a light, very light color I would probably go to a colder plug. Its very possible that the BR8ES may give you some more power, but then there is the problem with the ground electrode not being directly on top of the center core

I guess the only way to find out would be to peak tune with a BR8es-11 and then switch to a BR9ES plug and see if it fouls and chec peak RPM or even one of the racing plugs. I make take one entire day doing plug testing once I properly tune my carbs.

fercho, ill give it a try when i hit the h2o again.

i run the colder plug. have been since i blew the motor back in july. the increase comp. and ignition timing puts the electrode out of the safe temp zone.

i get a can get a good 10 hours on a set of br9ev plugs before they should be replaced.

take a good look at the porcelain with a magnifying glass. mine was detonating with the 8's...the ground strap sometimes showed detonation, but not always...

advanced timing + increase compression = 94 octane and one colder plug

70 hours and still strong.

Hop what RPM are you turning and gap on the plug. Remember small gap can also cause detonation.

We need to test it.

Fercho, for some reason I was thinking that I had a different plug with the stock head. I now have BR8ES so I will check to see what the gap is. Thanks. Also I checked my compression today for the first time since I got my boat back and I got readings of 120,120 & 115 on the rear. I was thinking that the pressure should be in the 145 lb. range. rp

43 gap and 7130 peak with the 14/20.5 and washer. 7100 consistent in the cold air... speeds in the low 72 area

I'm not sure how a plug gap that is shorter will cause detonation. "Detonation" is a result of excessive heat and pressure in the combustion chamber which causes the air/fuel mixture to ignite on its own.(Similar to the ignition process of a diesel engine)When detonation occurs, there are MULITIBLE flame fronts which collide with explosive force. "Pre-ignition" is sometimes confused with detonation, because they both have the same damaging effects, and pre-ignition can lead to detonation. "Pre-ignition occurs when the air/fuel mixture is ignited prematurely, usually by things like glowing carbon deposits, a spark plug with too high of a heat range, premature spark caused by a cross fire between plug wires, etc.Usually,pre-ignition has only TWO flame fronts which collide. Regardless of whether you call it detonation or pre-ignition, I don't understand how a shorter plug gap can cause this problem. I say this because the spark plug, if it is the proper heat range, can not cause pre-ignition, nor does it affect ignition timing. Consider the speed at which electricity travels. If a shorter plug gap would cause prematue ignition timing, or advance the timing, then all the plug wires would have to be the same length. All stock ignition systems do not efficiently ignite the air/fuel charge every time.Some high performance ignition systems read the resistance of the spark plug and actually refire it, if it senses a misfire. Also, by reading resistance, they can adjust the spark intenisity and duration, to prevent misfires. Regarding plug gap, for performance you want the widest plug gap that your ignition system and engine will tolerate, without loosing performance. Also, the heat range of a spark plug is not the heat of the spark, but the spark plugs ability to transfer heat from the center core to the cooling system. A colder plug, with a shorter nose, transfers heat more rapidly thus reducing the chance of pre-ignition. Generally, the more modification and related combustion heat dictates how cold of a spark plug is required. If the plug is too cold, it then allows carbon to build up on the plug, which could cause pre-ignition.---Just my thoughts and opinions.--

[ 01-12-2002: Message edited by: FrtrnrIV ]

I am passing information from several sites that I have read and info that I also got from MSD.

I persoanlly have not reduced my gap to confirm this nor I will.

I found this article

Gapping

Since the gap size has a direct affect on the spark plugs' tip temperature and on the voltage necessary to light the air/fuel mixture, careful attention is required. While it is a popular misconception that plugs are pre-gapped from the factory, the fact remains that the gap must be adjusted for the vehicle that the spark plug is intended for
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The explanation would be that the shorter the gap the hotter the tip of the plug and hot spots create pre-ignition which would lead to detonation

[ 01-12-2002: Message edited by: Fercho ]

FrtrnrIV - pre-ignition and detonation are the same thing to me....BAD NEWS. I knew the diff...but thanks for the clarification....

Well said!