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Lenny
07-29-2005, 09:32 PM
I went to a small lake the other day in the X18. I ran it as always, full fuel, me and my gal, nothing different. Hit nothing, ran great etc. Lake is at 1000'.
Water FAAAARRR warmer than my ocean I always play in, (in fact this is the first time I saw the temp guage EVER move)

BUT

WOT rpms went from 5400 to 4900-ish. Any ideas?

I don't want to over investigate this as I need to use it NOW. But do you think it dropped a plug/or cylinder?

It idles GREAT, runs great, smooth, all that. I pulled the plug wires at the plugs at 800 rpms and 2000 rpms. All have an effect only one or two are waaayyyy lesser an effect. I recently replaced my exhaust gaskets, (with Marine versions) and ARP bolts etc, and have retorqued twice now. The plugs (new) were black where blow-by has tainted a few. Could Carbon have taken its' toll on these or one at WOT?

Keep it simple please. You are talking to a guy that would rather go buy a new motor than fix it. ( I don't fix motors ) :)

Where did my 400-500 rpms go all of a sudden?

350 CHEV, VOLVO 280, NEW WIRES (Mallory), recent plugs, BG SEA DEMON 650 (new), NEW Mallory Marine (photo/electric) Superlite or something, Mallory Super Coil (new). Cylinder pressures are 125 all around except for one at 130.

Tach is accurate within 50.

Everything has worked fine for about 10 outings and 40 hours. This was at the Lake only and I have not used it since.

Thanx

tmdog
07-30-2005, 10:43 AM
Boating in freh water versus salt has to make a difference in speed. Flotation in fresh results in more wetted surface and probably lowers top end. The theory is there but is it true?

cobra
07-31-2005, 02:04 AM
Actually, you've got a double whammy. The fresh water provides less boyancy, more water friction. You also went from 0' altitude to 1000' which will lower HP due to a lack of oxygen. Being carburated, you also will tend to run richer A/F ratio, further killing power and giving the darker plugs. To settle your doubt, run it in your familiar teritory. If your power comes back, no problemo. The power drop is quite high for only 1000' elevation, but if the carb were already a little rich (as they usually are for safety reasons) that'd explain it. If you plan to continue running on that lake for an extended period you should try & get the carb re-jetted.