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Discussion Starter #1
Hello everyone,

I have the quad that I have listed in the thread title. I haven't worked on it in months, but the weather's getting nicer and I'm thinking about having another go at it.

I'll start with the night that that the problems started. I was riding around a bunch all night, no problems whatsoever. Eventually, I'm running it down through a field and it just dies. No sounds, no warning, just stops running.

I get it pulled back to my house and figured it was out of gas (my fuel gauge is broken and it was dark so I couldn't check the tank very well) so I filled it up and cranked it for about 5 - 10 minutes and couldn't get her to fire. So, I pushed it back into storage until the next day.

The next day, I go to check fluids, gas was full, radiator was full, oil was... empty? Almost completely dry. I about freaked. I've only owned the quad for about a year up to this point and it didn't really smoke and I never saw drops of oil on my floor and I had new oil that I was just about to put in it that weekend, but here we are.

I filled it back up, changed the filter and closed everything back up. I figured I was good at this point, but the problems continued. I crank and crank and crank and I just get the occasional "pop" with flame coming out of the intake valve and not much else.

I checked for spark and it was fine, my fuel is new, non-ethanol based 91 octane that I get from a local Royal Farms and my air filter is clean. Fuel is coming through the injector just fine (I don't have a pressure gauge, but by the looks of it, it isn't starving for fuel).

I did research and figured it could be something with the Throttle Position sensor, or maybe I sheared the D-key.

Mind you, that I do have an aftermarket ECM from Velocity Devices, but I installed the original ECM to do the TPS advance and retard tests. For some reason, I can't ever get it to be right. It's either retarded or just a minute little change makes it advanced. _C00 or ‾C00, never -C00.

Anyway, I went further based on a buddy's advice, to check that the D-key wasn't sheared off. I removed the side of the crank case where the pull start is, checked the chain tensioner and removed the cam cover. When I look in there, the cams seem to be aligned perfectly to TDC, but my friend believes that it's "180 out" and causing the fire to come out of the intake instead of exhaust and makes it not want to start.

I remember ordering a new crankcase seal last year, a new D key, some anti-freeze and putting everything back together and have it not start after putting everything back together.

Over this winter, I ordered a compression tester to see if I ruined the rings when driving it with no oil (Yes, I know I'm stupid).

I'm just writing this post to see if anyone had anything similar happen to their king quads and to let me know where I should be focusing my attention. Maybe the compression, maybe the TPS sensor, maybe somewhere else? I'm not sure at this point and I appreciate everyone's input! Hopefully I'll get to dive back into the project this weekend with temps in the 70's finally!

thanks all, and sorry for the long post!
 

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From what I researched online, the 700’s were still carbureted atv’s. Though I could be wrong, have you checked the carb/s at all..? Clean them, install a carb kit..?


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Discussion Starter #3
Thanks for replying! No, this is a fuel injected bike. I have the service manual here: Index of /files

Fuel injector pumps a good amount of fuel when cranking. If I spray fuel down into the throttle body, I'll get flames shooting out of the valve body but she still won't fire.
 

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Discussion Starter #4 (Edited)
Well, over the weekend I went to put my compression tester on and found out that the spark plug is a 10mm x 1 type thread, and my tester didn't fit. I ordered an adapter online that just came today.

Put it on, cranked and found a whole 15 PSI. Guess I found my problem.

https://photos.app.goo.gl/PzkNjiHOFuczjlP43

I'll be putting new rings and stuff soon I guess. At least I'll be able to learn a lot about the motor?
 

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Did you the test with the throttle held wide open..?


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Discussion Starter #6
No, was I supposed to? I just took out the spark plug and screwed the compression tester in as tight as I could and cranked.

This is my first quad and I've never had to rebuild a motor before, nor test for compression for anything. I'm looking at micrometers and dial gauges on amazon trying to figure out how much everything is going to cost.

New cylinders are around $600, gonna be an expensive project, ha!
 

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Discussion Starter #7 (Edited)
Ah, just watched a video and then RTFM and found that I'm supposed to fully open the throttle. Wonder if it's going to make that much of a difference. Guess I'll give it a shot.

If it's anywhere near what it's supposed to be (142 PSI, yeah, right!) then I'll do a wet test as well.

EDIT - Just tried again with throttle depressed completely and got the same result. I'm not sure if my compression tester is the best thing in the world either, I got it from Advanced I think:
https://shop.advanceautoparts.com/p/actron-professional-compression-tester-kit-cp7828a/9090005-p?c3ch=PLA&c3nid=9090005-P&adtype=pla&gclid=Cj0KCQjw_ODWBRCTARIsAE2_EvUYsBaSN3Ijvr4U6V4XP83xI7uzikslns4FuDJIPZQ3d1Od7QdO_FcaAqJyEALw_wcB&gclsrc=aw.ds
 

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Discussion Starter #8
Well, it took a while and about $1100, but she is running again! Purchased a used head and had my jug sent out to be re-plated and got a new piston.

The cool part about these motors are the fact that the 700 and the later 750's used the same bottom end and cylinder head, only a different sized piston and jug, so I have an '06 700, but it's actually a 750 :)

Also, big and expensive lesson learned... CHECK YOUR OIL!
 

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Congratulations! Great to hear you got your machine back running. Fresh bottom end ,sounds like you got 750 rings, she must run nicer now 😄 hahaha, yep I always check my oil, every ride..
 
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