ATV Help & Brand Specific Topics

I ended up welding a bombardier 400exhahst onto it ... And then it still backfired , I discovered more holes up near the head, I'm going to use some high heat jb weld to patch them

Thank you for your insight. I will check on the oil in the sump when I get a chance.

The most common reason for that oil in the airbox, and especially if it starts doing it suddenly, is that the sump is full of fuel. A sump full of fuel would also cause the engine dieng once it starts to get hot. I'd suggest checking the oil level as the first thing. A lot of bikes also have restrictor valves or orifices in their breather hoses, and in some models if that restrictor blocks up it can cause problems like the oil in the airbox.

Hi guys. I have a problem where the quad will start and run well for about 5 minutes and then it dies. On inspection the airbox has oil in it (quite a lot). The oil is pumping through the cylinder head breather hose. This problem first happened suddenly. I have since done the top end including, piston, gaskets, rings and valves. I have also done the carb (not that I thought that this was the problem). The compression seems normal. The only thing that I can think of, is that I did not grind the valves well enough. Anyone experienced this? If so, how did you fix it? Any other thoughts?

Gator idling (or trying to)

You can adjust the throttle in the throttle body but would have to set it to about 4,000 rpm to keep the motor running. Low idle is entirely different than erratic idle (up down, up down -> dead)

Thank you!!

Thank you, I can't remember which year it is so I will have a look later today and find out.

Thanks, I will strip out the loom and check the wiring, it needs checking anyway!!

The throttle cable is sure to have some adjustment somewhere. Polaris bikes have a kill switch built into the throttle and if there is slack in the cable, such as you would get if the throttle stuck on and your thumb was off the pedal, then it kills the engine. If those get too much free play in the cable at idle they kill the engine. It wouldn't surprise me if JD did the same. Apart from that though, if the throttle is held too far open, by the cable or someone having adjusted some stop somewhere, then the idle control motor or valve can't compensate enough and keeps the idle speed wound right down to zilch as much as it can, and that sets off a cycle of compensations and counter compensations that often ends in an engine not idling. I don't have the book, but I'd bet it says to check those things, and do a standard sort of tune and inspection of hoses etc.

Not much to the throttle body that you can access. There are only 2 little holes where are the good stuff is located that cannot be serviced. Just pulled out the entire throttle body and cleaned it (wasn't really dirty) but don't expect it to do much.

Nothing beats a cigarette, Wish I still smoked The 02 sensor was bad (threads were stripped and it fit loosely in the housing but wasn't the real problem. Can disconnect both 02 sensors and no change. Throttle cable not really adjustable and IAC is integral to the throttle body and not serviceable.

I’m with @Mech check power at relay.

With fuel injection, it’s like a car… I would take the throttle body off and inspect. Maybe get some throttle body cleaner and spray it first and see what that does.

It's likely that the O2 sensor wasn't defective. It quite likely was just struggling to control the mixture within acceptable limits and so reported it as not working. That's quite common with O2 sensors. They are one of the most miss-diagnosed components. I'd be checking the throttle cable adjustment, the fuel flow and pressure, the IAC operation(might operate on 5volts so be careful), and the spark plug gap and condition.

You have power to the relay, so now you need to check the relay is getting power to activated it, and that it has an earth on it's activation windings. If that side of the relay is operating, you need to check whether the power is getting from the relay to the pump, and that the pump has an earth. If you tell us what year and model this is I'll try to check in a manual how the pump and relay are actually wired. It's possible that the pump, or the relay, are powered and then get switched by connecting an earth to one or both of them.

That's a good point that often goes underdiagnosed with older quads, especially if they are sitting around. flush teh tank and change the inline fuel filter.

Do you have a smoke machine? If not, I would get a cheap one and search for vacuum leaks around the intake. I have one from amazon I use on my cars and stuff like this, works pretty good with baby oil. Amazon Link

That is the problem with this machine. Everything is in the throttle body ($1,200+). Haven't found a vacuum leak.

Did they ever get back you? Were you able to get it going?

Did you ever figure this buttoned up? Good video on clutch removal Hisun 550:

Do you have power at the fuel pump relay?...actually I see you posted that. I would start checking the wiring from the relay to the pump.

My guess is that its at the throttle body and something with the idle air control. Some have separate IAC motors, this looks like its all part of unit. I would also check for vacuum leaks.

OK, now that we are through all the BS and I simply purchased the service manual, let me tell you the problem with the machine while I dig into the manual... The engine starts fine but does not idle. You have to keep pumping the throttle to keep it alive. You can go fast down the road and she goes, but idle no. It did have a bad 02 sensor but fixing that had no effect. In fact, unplugging the 02 sensor does not make a difference. Have not unplugged both - will do that tomorrow. The problem with the 850i is that all your sensors are in the throttle body and are not serviceable (and it is not a cheapo piece). Will probably have to start ripping the engine apart?

I have yet to find a free manual. The TM109919 is for all years so the 2014 would be fine. So again, what are my choices (cant find a freebie): 1. Post a bunch of worthless posts just be be cheap and get the manual for free 2. Buy a manual on eBay for about $30.00 (a CD) 3. Buy a download from some other stranger for $25 4. Donate $29 to you folks. I think I will choose #4 as I need it now, Maybe you folks will have the parts manual too and make it double worth while.