[texaslawdawg]

So you see a lot of posts on here about limp mode. Well let's break limp mode down for people who may not be mechanically saavy. Your ATV may be equipped with a fail safe that we call "limp mode". What happens is that your machine has thrown a semi-serious to a serious code through your ecu/cdi (the brain of the ATV). When this happens it sets in place a governor meaning your ATV will only perform up to a particular speed, rpm, and even possibly temperature. You may see this as your engine "bogging" at full throttle.

Many things could cause this. Common codes that cause this could be a bad belt, low oil, bad timing and the fan favorite the belt slipping. You can see what this problem is on your instrument cluster, maybe your oil light or belt light is blinking when the key is turned on but the engine is off. Just like a cars "check engine light". It won't come out and just tell you the problem so you'll need to eliminate common issues. Water in the oil? Low oil? Old oil? Belt slipping? Carburetor issues?

There's a few popular ways to fix these issues involving several steps. For belt issues you will need to take the belt housing off. There is a switch on the inside of the cover that should be switched to the "on" position. Unplug the sensor for the belt and unplug your ecu. After this turn your ATV on by the key. This should reset the memory of the ecu/cdi. Other steps may be necessary depending on the type of your atv. With some homework this can be accomplished. The main thing to do is to reset the memory on your ecu/cdi whatever the problem.

Also your ecu/cdi could be bad if you've run it in water or other things. You also may want to check into replacing it if this doesn't work. A Dynatek is said to eliminate the limp mode on your atv.

Hope this helps someone.

 

[doorfx]

Limp mode is only in 2004-06 650 v2 correct? There is no belt trip switch on the machines I have worked on

 

[texasrapier]

Most of what law dawg described described applies to the 650 v2.
The v2 would also throw a belt warning every 1000 miles for service for the belt to be inspected.

The h1 also have limp modes. but the primary reason for an h1 to go into limp is a faulty or reversed diode. another is a faulty shift position sensor. No signal equals reverse default in the ECU witch turns on the speed limiting circuit.

I'm not sure about the 650v2's but the h1's do not have any kind of oil pressure safety. I think high water temp will also turn on the limp mode.

 

[J_Fred]

And if you want to never worry about limp mode again, just buy a Dynatek CDI box.