2019 Hisun Sector 550 Hard Starting

[kgs]

Got a hisun sector 550 2019 that's got 5900 Miles on it, this year it started to getting hard to start in morning, once I get it started it works good the rest of the day. But to start it in the morning I got to hold the gas pedal to the floor and it will fire up. I replaced the fuel injector but didn't help it. So I just ordered a new air filter and 02 sensor and a maf sensor to put on it to see if this will fix it. Anyone else had this problem. I'm hoping the parts I ordered will fix it. I also bought a new battery to put in it also.

[kgs]

Any help on this at all would help thanks, I bought OEM parts to put on it. My next thing to check if this don't work is check my valves to see if they need adjusted, but taking the cover off to rotate motor looks like a pain in the but to get to.

[aefron88]

I would check the valves and replace fuel filter before throwing parts at it.

The fan cover isn't that bad, and you can get away with just pulling the top bolts and flexing it a little.

Pull the spark plug and the engine is easy to spin by hand.

[kgs]

Ok thanks for the reply, I already ordered the parts will be here Tuesday but will go ahead and see if they are set at 5 thousands. Thanks 

[kgs]

Well turning motor fan counterclockwise until valve is at top then move fan another 3/4 turn to make sure the lobe is off valve. I don't have any room at all to put a gage in It. seems like it keeps contact and no opening. Would this cause it hard to start but run fine once started.

[kgs]

I think I'm going to put it back together and see about taking it to a shop and let them adjust them. I don't want to mess something up. I have rotated piston up two different times to check clearance on the up stroke and I can't get a gauge in but the motor is cold.

[aefron88]

You may very well have zero lash. Back off the adjusters and go from there. As long as it's off the cam lobe you should be ok to adjust em.

 

Yes this may cause a hard/no start situationnloss of power, poor runbing, etc. If the valves are slightly open you will loose compression.

[kgs]

When I took my plug out it was toast, changed it last summer. You can see it's running rich. I put it back together and it fired up a lot easier with new plug, but I know the valves need adjusted there is 5900 miles on it. So there is only two valves intake and exhaust, so if I have my pistol dead top of stroke with valve up then it's ready to loosen and adjust, then repeat for next valve, I just want to make sure I don't want to do something wrong and it won't run. Probably don't need the part's I ordered but I will keep them. Here's picture of old plug.

[aefron88]

Yep that plug is definitely shot.

You got it on the valve adjustment. It's a lot easier than it sounds just takes a little contortion to get in there. I have a post here explaining how to do it on the 400 with pictures. The 550 should be very similar

[kgs]

Thank you, that was a good read on the valves.

[aefron88]

Let me know how it goes, and if it fixes your issues or if we need to further troubleshoot.

[kgs]

Well adjusted the valves to 5 thousands, now it runs like when I first bought it. Turn the key fires right up and idols on it's own, very happy man. Thanks for all the help.

[kgs]

So if you have a hisun sector 550 it's a 4 stroke, which means the piston goes up twice before you get the compression stroke. Set piston TDC on compression stroke then adjust both valves to 5 thousands clearance. My utv runs like the day I bought it from this fix. 

[aefron88]

Correct, sorry if I forgot to mention that. Like any 4 stroke the cam goes a half turn for a full turn of the crank.

Glad you got your issue sorted! Hopefully you get another 5900 miles!

[kgs]

Yes I hope I do, I only use it to haul corn to feed deer, so it don't get abused driving it hard in woods. I've been told the motor in the sector 550 is the same motor in the sector 750 and supposed to be a good motor in the hisun utvs.

[joe1]

On 10/14/2022 at 2:08 PM, kgs said:

Got a hisun sector 550 2019 that's got 5900 Miles on it, this year it started to getting hard to start in morning, once I get it started it works good the rest of the day. But to start it in the morning I got to hold the gas pedal to the floor and it will fire up. I replaced the fuel injector but didn't help it. So I just ordered a new air filter and 02 sensor and a maf sensor to put on it to see if this will fix it. Anyone else had this problem. I'm hoping the parts I ordered will fix it. I also bought a new battery to put in it also.

I have the same issue with mine right now done change the same parts and no luck if you happen to figure it out help would be appreciated 

[kgs]

I had the same problem, it was my valves that got to tight.

Adjusted both valves to 3 thousands and now starts right up and idols good.