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#4261165 - 11/29/16 03:36 PM kymco mongoose 90r, carb issue.
jstutz Offline


Registered: 10/06/08
Posts: 1556
Loc: NC
Guys, I have a kymco mongoose 90r ATV. I believe they are similar to some arctic cats but not sure about this. Typically i have had issues with the needle jet clogging up and making idle very poor. My latest problem is a little different. The ATV is running very rich. It will start and idle perfect every time even when cold. The problem is when i give it gas under load it has little power and starts choking out. I did notice that my idle was a bit higher this time and i had to back it down. There is so much gas getting into it that , at times, you can see black smoke out the pipe. It is running very poorly under load and higher revs. This is my first experience with the auto choke or bystarter.

As far as troubleshooting :

Pulled carb apart and checked jets, both are clean.
Tried different adjustments on air screw and idle and cannot fix.
Pulled plug and sure enough it is black and wet.

Assumed it would be the auto choke or bystarter so I pulled it out measured the resistance and it measured 6 ohms. Hooked it up to a 12 V source and verified that under 12 V and after 3 mins it expanded out about 3/16 of an inch. Seems like it is working to me.

Im wondering if maybe its not getting voltage from the harness which would leave it open and flood it out. (I think) I may pigtail a set of wires off to measure voltage while operating to see if im getting voltage.

Anyone else have any ideas or comments.

Any help would be appreciated.

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#4261456 - 11/29/16 08:14 PM Re: kymco mongoose 90r, carb issue. [Re: jstutz]
JetStar Offline


Registered: 10/02/08
Posts: 1541
Loc: Flatlands of Indiana
Not familiar with this type of carb, does the electric choke operate a butterfly or an enrichment plunger?
verifying you are getting voltage to the choke is a good start.
_________________________
My weakness is I love all motorcycles regardless of brand
2017 Wide Glide
2016 Suzuki DR650
2015 Road Glide
2007 Yamaha FZ1
1978 Suzuki GS1000 (now 1085)

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#4261468 - 11/29/16 08:36 PM Re: kymco mongoose 90r, carb issue. [Re: JetStar]
JetStar Offline


Registered: 10/02/08
Posts: 1541
Loc: Flatlands of Indiana
Looks like it's a plunger. Provided it's expanding far enough, does it have a rubber washer or seal in the end of it?
_________________________
My weakness is I love all motorcycles regardless of brand
2017 Wide Glide
2016 Suzuki DR650
2015 Road Glide
2007 Yamaha FZ1
1978 Suzuki GS1000 (now 1085)

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#4261720 - 11/30/16 09:36 AM Re: kymco mongoose 90r, carb issue. [Re: JetStar]
jstutz Offline


Registered: 10/06/08
Posts: 1556
Loc: NC
It is a plunger that as it gets warm, plugs a fuel inlet. I didnt notice any rubber washer but I will check it tonight and see.

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#4261721 - 11/30/16 09:39 AM Re: kymco mongoose 90r, carb issue. [Re: jstutz]
jstutz Offline


Registered: 10/06/08
Posts: 1556
Loc: NC
Verified that im getting voltage and direct connected to battery to ensure 12 V. Runs the same as it did before. Still flooding out. Aparently you can take a small hose and blow thru a hole to verify it is closing as sealing. Ill do that tonight. This will be the end all answer as to if the enrichment ckt is bad or not. If bad then i just have to figure out what is bad because it appears to be working .

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#4262231 - 11/30/16 07:09 PM Re: kymco mongoose 90r, carb issue. [Re: jstutz]
JetStar Offline


Registered: 10/02/08
Posts: 1541
Loc: Flatlands of Indiana
If the choke checks out good, then start looking at your float and float valve. If its not shutting of the fuel at the correct level and allowing it to run high, it will run rich.
_________________________
My weakness is I love all motorcycles regardless of brand
2017 Wide Glide
2016 Suzuki DR650
2015 Road Glide
2007 Yamaha FZ1
1978 Suzuki GS1000 (now 1085)

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#4262238 - 11/30/16 07:18 PM Re: kymco mongoose 90r, carb issue. [Re: jstutz]
spasm3 Online   content


Registered: 05/30/10
Posts: 8665
Loc: North Carolina
Here is a link to the carb diagram , you can zoom up for part numbers.

I would look closely at the float in case it got bent during disassembly/reassembly.

http://kymcopartsonline.com/catalog/sear..._diagram_id=499


Edited by spasm3 (11/30/16 07:22 PM)
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13 elantra 68k 5w30 QSUD
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#4262515 - 12/01/16 07:30 AM Re: kymco mongoose 90r, carb issue. [Re: jstutz]
jstutz Offline


Registered: 10/06/08
Posts: 1556
Loc: NC
thank you guys. Ill keep you posted

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#4785624 - 06/13/18 08:48 AM Re: kymco mongoose 90r, carb issue. [Re: jstutz]
jstutz Offline


Registered: 10/06/08
Posts: 1556
Loc: NC
I know its an old post but started back into this problem. As mentioned above I tried to keep working the float level down to be sure its not too high. It did not help. I bought a new auto enricher and it made no difference. I took intake manifold gasket RTV and sealed the gas ports of the auto enrichment circuit to be 100 percent sure that it is not leaking. Now i have to hold my hand over the airbox so it will start. I put the needle jet clip the entire way at the top so it is as lean as can be and that seemed to help but still cannot get top end without bogging and choking out. I pulled the plug on the exhaust , near the head, to make sure enough air was getting thru the exhaust. That seemed to make no difference. The air cleaner is removed and clear going into the carb. I bought a new plug with no improvement. I did a compression check and it pumps up to 121 psi.

Someone mentioned above that maybe the carb was not shutting the gas off and that would make it run rich. Wouldn't that flow over the overflow tube though? The carb does not leak gas. I cannot understand for the life of me how this thing can run so rich at the top end. It idles perfect and runs great up to about half throttle.

Any other suggestions would be greatly appreciated.

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