Pre-detonation
- Thread starter dre2992
- Start date
How do you know it has "pre-detonation"? Perhaps its an air leak, or lean condition. Have you did a leak down test on your engine? What have you done to your engine... exactly. We need LOTS of details, so we can help you. Lay it on us... what modifications were done, pipe, carb, jets, fuel, air filter, reeds, piston, etc.. Do you have any photographs of the blown up engine you repaired?
I have a 260 Main jet, air lid off, FMF full exhaust, and Namura piston, i'm running 32:1 bean oil and has not blown up yet, and I do not want it to, and I know it's pre detonating because that's what everyone has told me on why my other piston has a hole in the middle of it it's all I can think of right now
What the hell does that mean??? /\ /\ /\
Back to basics, did you check for leaks with a leak down test and a plug chop?
yea to both and and sorry I'm sure that doesn't make any sense I'm talking to my phone because I'm lazy lol
Hole in the center of the piston could be a timing issue, check your flywheel key and positioning of your stator.
FMF pipe with the air box lid off and 32:1 premix would prolly need a 300 main jet.
Needle on middle clip.
B8es plug.
Plug chop to confirm!
Needle on middle clip.
B8es plug.
Plug chop to confirm!
I started to get some with my +4 timing. So I backed it off a degree and it went away. You have stock timing?
THAT /\ !!!!!!
but I'll say it again............
260 main with FMF, lid off and fuel/oil mix is way too lean.
no way a plug chop came back correct !
290 - 310 main depending on your elevation.
if I remember correctly your in virginia near sea level ?
sea level requires richer jetting than higher elevations
plus...... run 93 octane, higher octanes fuel helps prevent detonation.
Why are you running a hotter plug? Has your head been milled? What does a compression test revel?
Running a hotter plug will not change the combustion temperature.
Combustion temperature is controlled by the air fuel mix, high compression with a low octane fuel and the degrees of advance to the timing.
Once and for all, there's no such thing as pre-detonation. I don't even think it's a word.
1. Pre-ignition
2. Detonation
Your main jet is too small for your mods, causing a lean condition leading to detonation.
1. Pre-ignition
2. Detonation
Your main jet is too small for your mods, causing a lean condition leading to detonation.
Detonation: Detonation is the spontaneous combustion of the end-gas (remaining fuel/air mixture) in the chamber. It always occurs after normal combustion is initiated by the spark plug. The initial combustion at the spark plug is followed by a normal combustion burn. For some reason, likely heat and pressure, the end gas in the chamber spontaneously combusts. The key point here is that detonation occurs after you have initiated the normal combustion with the spark plug.
Pre-ignition: Pre-ignition is defined as the ignition of the mixture prior to the spark plug firing. Anytime something causes the mixture in the chamber to ignite prior to the spark plug event it is classified as pre-ignition. The two are completely different and abnormal phenomenon.
Pre-ignition: Pre-ignition is defined as the ignition of the mixture prior to the spark plug firing. Anytime something causes the mixture in the chamber to ignite prior to the spark plug event it is classified as pre-ignition. The two are completely different and abnormal phenomenon.
is says missouri goes from 230 to almost 1800 in elavation changes so u have to be more specific
http://www.netstate.com/states/geography/mapcom/mo_mapscom.htm
you should be running a ngk b8es plug and 87 or 89 octane gas
http://www.netstate.com/states/geography/mapcom/mo_mapscom.htm
you should be running a ngk b8es plug and 87 or 89 octane gas
