advanced timing and detonation

[la400ex]

I bought my 400 used from a dealship that sells only used quads. I was told that the engine was stock. I was talkin to a car mechanic the other day. His son rides quads. I told him about my rod breaking. He asked if my timing was advanced any. I didnt think it was but i didnt know for sure. I have heard a lot about not putting an advanced timing key with a high comp piston. Could that have caused my motor to detonate and snap the rod? Make any sense? Does the advanced timing key look any different from the stock one? I will pull my flywheel and check it out. Thanks, Anthony

[Martin Blair]

yes it is not reconmended to use the timing advance with a hi compression piston set up.

[lex luger]

hell yeah its possible, if you run low enough octane with timming advanced far enough, it can *ping* and snap a rod, or blow a hole in the piston, what did you'r plug look like?

[la400ex]

The plug was almost white with a 170 main which should have been good or even a little rich. Is there any way to tell if the timing was advanced? It was a 10.8:1 and i was running 93 octane. Thanks, Anthony

[airheadedduner]

If there was detonation then there will be marks on the piston. There should have been deposits on the center electrode. Pull off the flywheel, if the flywheel key looks like a "z" insted of a "l" then it is an aftermarket advanved key.

[400exBro]

that timing key should have a slot cut out that is facing up... the stock one is smooth and round, bacily...

i just installed one on a stock engine for the ex, no high comp piston or anything.... what kind of percausion should i take??? should i put some octane booster into my feul??

thanks

[Leo]

If there was enough detonation to break the rod the top of the piston would be a mess.. I'd be willing to bet there would be signifigant evidence of detonation (like little aluminum splatters all over the combustion chamber / plug..

First thing I'd be looking at is the CDI.. bet it's an aftermarket with no rev limiter :devil

Leo

[YZROOSTINYA]

i am running a 11:1 on 93 with no pinging

[400exBro]

Originally posted by YZROOSTINYA
i am running a 11:1 on 93 with no pinging


ya but you are not running a timing key are you???

i wanted to know if it is a good or bad thing to run octane booster with a stock piston... but a sparks advanced timing key???? some people say they had to run a 50/50 mix of race gas and pump.,, so can i use octane booster instead...???

thanks

[UglyMotha™]

Originally posted by 400exBro
ya but you are not running a timing key are you???

i wanted to know if it is a good or bad thing to run octane booster with a stock piston... but a sparks advanced timing key???? some people say they had to run a 50/50 mix of race gas and pump.,, so can i use octane booster instead...???

thanks



that's a good point i have a sparks key however i havn't fired up my machine yet to know what's it's goin to do:confused:

[400exBro]

Originally posted by UglyMotha
that's a good point i have a sparks key however i havn't fired up my machine yet to know what's it's goin to do:confused:

either have i... that i why i am wondering so i can start her up and make sure it runs fine... i have let it warm up by idling... and with the key i felt that it will start a llloott better then stock... and throtle is a lot crisper... i like it so far but i want to get her wide open on some dirt!!!!!

[cheetah]

I ordered one a long time ago and it is still sitting on my desk. I decided not to fool with it because it seemed fairly complicated to me and I'm not the most mechanically inclined.

[shamisc]

Originally posted by la400ex
The plug was almost white with a 170 main which should have been good or even a little rich. Is there any way to tell if the timing was advanced? It was a 10.8:1 and i was running 93 octane. Thanks, Anthony



White!! It's lean dude!! Probably overheated among other things. How do you know it's 10.8:1? It could be 13:1 for all you know. I don't think the rod would snap like that with 10.8:1 unless something was just not right, piston installed backwards, etc. :confused: :confused2

[400exBro]

bump