You may not believe me, but can you explain why this happened

Joined
Oct 28, 2010
Messages
923
Re: You may not believe me, but can you explain why this happened

Pull the head, look at the top of the piston or decarb and see if problem goes away. Does the motor have the correct heat range spark plug?
 

Jogin

Cadet
Joined
Dec 9, 2010
Messages
19
Re: You may not believe me, but can you explain why this happened

yes it has proper plugs in it, and it is the dieseling issue, i had called and talked to him some more and he had said that apparently it is more common than he had thought, but since 99 percent of the time we always run them with a test prop in the test tank, and that is how he usually does it if it is not actually on the lake. That I guess is why he had never seen it. He had also told me they got back from lunch and did a compression test and it had nearly a 30 pound difference. He assumed that the other student had done a compression test on it in the first place. I really appreciate everybodies thoughts and advice on it, I guess ultimately we had all learned our lesson. Also whomever was talking about the vacuum kill switch, is that an option BRP offers as an add on for such a situation, or is it something that either comes with it or it does not?
 

scooper77515

Senior Chief Petty Officer
Joined
Sep 3, 2010
Messages
753
Re: You may not believe me, but can you explain why this happened

Jefferson...yes, the Rotax. "They" always said it was from an air leak or something "wrong" but I had three that did it and had them apart several times and never saw anything that would cause it.

The volvo does it but not like the Seadoos. It just sputters for a few seconds after you kill it.

The seadoos would just keep revving up and scream until you choked it, gassed it, or it tossed a rod. Even went past the rev limiter because it wasn't being "fired" electronically and wasnt being controlled by the coil.
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,226
Re: You may not believe me, but can you explain why this happened

The vacuum cut-out switch was on all 22, 25, 28, 30, 33, 35, and 40hp OMC-built motors in the 1950's into the 1970's. (That is, except the 22 cubic inch 25hp).
 
Joined
Oct 28, 2010
Messages
923
Re: You may not believe me, but can you explain why this happened

The volvo does it but not like the Seadoos. It just sputters for a few seconds after you kill it.

I would look at your ventrui cluster, may be leaking a little bit, what year Volvo? Straight points or newer.
 

Flysfloatsor

Banned
Joined
Oct 7, 2010
Messages
202
Re: You may not believe me, but can you explain why this happened

Compressing fuel/air will cause ignition. This event is what causes knocking in engines when too low octane fuel is used. Higher octane actually means LESS combustable (in a sense) so it can be compressed more and essentially "wait" to be ignited by the spark plug.

Why isnt this covered in the class?
 

scooper77515

Senior Chief Petty Officer
Joined
Sep 3, 2010
Messages
753
Re: You may not believe me, but can you explain why this happened

what year Volvo?

Right below me in the signature. 2003? I think.

I will look up what those mean. Never heard of a Venturi Cluster.
 

scooper77515

Senior Chief Petty Officer
Joined
Sep 3, 2010
Messages
753
Re: You may not believe me, but can you explain why this happened

Books shows that it is likely electronic ignition. Nothing about points.
 
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