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2001 130TLRZ 2 Stroke - Limp mode?

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Mavis2

New member
Background: I have a recently rebuilt 130TLRZ 2 stroke. Professionally de-carbed last June. Was running great. Replaced gauges with "6Y7" pro series analogs. (None of the old gauges worked). Tach has oil and temp lights. When installed, oil light comes on at "key on" (no ignition) then goes off as it should. The temp light comes on and stays on; and stays on after ignition too. Also, I recently installed new plugs. It may be coincidental but it seemed to idle rough (bumping side to side a little) after the new plugs.

So, the issue: Launched yesterday to test things. Wanted to see if it was actually running rough, under load, or just my perception. It was a little rough at idle and when I gassed up it would only accelerate so far and "chop/bump" as if the timing was off, hard side to side movement. Pulled the plugs and all 4 were oily and wet. Did it go into limp mode? What would trigger the light without the motor being on? Bad sensor? Are the light and rough acceleration related?
 
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No such thing as a "limp" mode in a Yamaha. It is known as RPM reduction mode. Means there is a problem. Motor should be stopped immediately. Limp along and the motor can be destroyed.

The over temperature light being on is a clue. The same ground that turns on the over temperature light tells the CDI assembly that the motor is too hot. In which case the CDI will put the motor into RPM reduction mode.

The thermoswitches close due to excess temperature. When they close they apply a ground to the CDI and the tachometer light. Inspect the thermoswitches. Inspect the wiring from the thermoswitches to the CDI and to the tachometer.
 
boscoe said:
No such thing as a "limp" mode in a Yamaha. It is known as RPM reduction mode. Means there is a problem. Motor should be stopped immediately. Limp along and the motor can be destroyed.

The over temperature light being on is a clue. The same ground that turns on the over temperature light tells the CDI assembly that the motor is too hot. In which case the CDI will put the motor into RPM reduction mode.

The thermoswitches close due to excess temperature. When they close they apply a ground to the CDI and the tachometer light. Inspect the thermoswitches. Inspect the wiring from the thermoswitches to the CDI and to the tachometer.
Click to expand...

Thank you for responding. I agree. It's too coincidental that I just connected a new tach and the light's staying on, for no other reason (engine not running). With my limited knowledge, I suspected what you're describing, just wasn't sure how to say it. Ref. "limp mode", gotcha, I'll heed the warning. :)

I don't have a manual and have been looking for images/schematics...any suggestions? I have a rigging catalogue but not a manual. (I know, I should just order one. I'm cheap.)

Thanks Boscoe.
 
The diagram is in the applicable service manual. The wire colours are gray/black. Here is the diagram with the gray/black wires in red for better visibility.

 
Boscoe, I followed the wires from each temp sensor through all the connections between the motor and the console. All look good. When I disconnected the sensors at the motor (x2) the temp light on the gauge would not go off. I installed an adapter between the existing conventional "pre 2004" harness (pink/black/orange/grey, 4-wire) and the gauge. Checked it, all looked good. Disconnected the grey loop to see what happens, turned the temp light off. Whatever causes the lights to turn off after start-up is working on the oil light and not on the temp. What ground should I check? When the light stays on like that (grounds) does it queue the CDI to reduce RPM?
 
What tachometer do you have? Does it have two four pin connectors or just one four pin connector?

Sounds like the one four pin connector. If so, see the diagram below.



 
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Mavis2 said:
Boscoe, I followed the wires from each temp sensor through all the connections between the motor and the console. All look good. When I disconnected the sensors at the motor (x2) the temp light on the gauge would not go off. I installed an adapter between the existing conventional "pre 2004" harness (pink/black/orange/grey, 4-wire) and the gauge. Checked it, all looked good. Disconnected the grey loop to see what happens, turned the temp light off. Whatever causes the lights to turn off after start-up is working on the oil light and not on the temp. What ground should I check? When the light stays on like that (grounds) does it queue the CDI to reduce RPM?
Click to expand...
Yes. The same ground that turns on the tachometer over temperature icon tells the CDI assembly to put the motor into RPM reduction mode.
 
boscoe said:
What tachometer do you have? Does it have two four pin connectors or just one four pin connector?

Sounds like the one four pin connector. If so, see the diagram below.



Click to expand...


It a 6Y7-83540: single 4 plug with red/blue strip and brown/blue stripe.

When I disconnected the grey loop previously, the light would go out. I would not get the momentary on (on a few seconds then off) when keying on though, like the oil lights. Should it do the same?

Also, if I want to reconnect the buzzer, do I just tie back to the red/blue and brown/blue on the pigtail?
 
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