Buzzer/alarm keeps going off???

[jerryjerry05]

2004 Yam 150 carb.150TXRD
The motor runs GREAT up to 3800-3900 and then the alarm starts.
It's NOT overheating, I used a heat gun and checked the temps on each cylinder.
Not getting anywhere's near hot
New water pump.

The owner replaced both oil sensors/senders in the tanks.
Any idea's or tests I can do to check?

THANKS, JERRY

[boscoe99]

With alarm sounding check for low voltage to the CDI unit.

[ausnoelm]

Fist thing you need to determine if it's an oil or temp alarm, going by your symptoms, best guess is heat, blocked cooling passages, but, that said, it may be an oil delivery issue, don't just stab blindly, trouble shoot.

[Keithbaja]

Be Advised those tank switchs can be VERY tricky. I'll usually order new tank with switch for warranty reasons. Motors blowing up due lack of oil will get u bad name quick around the bay. Sometimes it's best to do the whole kit and kaboodle. ( where in the hell did that come from ?) Also run on mixed fuel tank till confirm oil is being sent...

[ausnoelm]

Be Advised those tank switchs can be VERY tricky. I'll usually order new tank with switch for warranty reasons. Motors blowing up due lack of oil will get u bad name quick around the bay. Sometimes it's best to do the whole kit and kaboodle. ( where in the hell did that come from ?) Also run on mixed fuel tank till confirm oil is being sent...

Why/how can a switch be bad only over a certain RPM? The filter being blocked maybe. But it still remains that so far, what is setting the alarm, oil or temp, no use rooting around with the oil system if it's a temp issue, and vice versa.

[99yam40]

what are your gauges telling you when this alarm happens?
if there is no oil level or overheat indicators showing up and you have proved those indicators work properly by testing them, then what Boscoe posted is the only other thing I can think of that can sound the alarm on some motors