KFX 700 Hard to Start, Occasionally Dies at Idle, and Bogs Occasionally

[Adrian Ciotinga]

Hello,

I recently picked up an ‘07 KFX 700. All was going well, rode it about 40 miles, when it started bogging at low speeds. If I kept the revs higher, I was just fine. Also, a persistent issue since I picked it up is the fairly difficult start (but it is abnormally cold right now and the quad is jetted for the dunes at summertime).

Regarding the complete lack of idle, I have to rev it a couple times to get it to idle after starting it, after which it’s 50/50 whether it remains idling. I don’t have low fuel, but all of this began after I rode it pretty hard and the radiator fan kicked in. Might be overheating, just wanted to hear your opinions.

[Adrian Ciotinga]

Crisis averted! It was overheating. After leaving it an hour to cool it star ya just like before and idles great. Rode it around the block a couple times and everything’s in order. One question though: is this air duct (coming from the CVT) meant to be like this?

[Frank Angerano]

The duct looks fine. That engine is water cooled. Over heating is never a good thing. It really stresses the engine. Check the thermostat or the water pump. The sensor that brings the fan on could be lagging and coming on a little late as well.  
Check your coolant level and that its moving fluid through the system.  

[Adrian Ciotinga]

Yeah, I was low on coolant. It was at the minimum fill line on the reservoir.

[MarkinAR]

I had a 4 wheeler a bit ago that was hard to idle, hard to start, popped at WOT after running a while...always ran great cold.  Issue on that one turned out to be trash in the bottom of the gas tank.  As you ran and disturbed the gas it would shake up the bits and clog the screen on the petcock.  After it sat a bit, the trash would fall off the petcock and it would run fine again until it stopped up again..vicious cycle.

cleaned the tank and never had an issue with it again.

Might be unrelated to your issue, but something to consider.