TAOTAO 250 Rhino - Can't tune Mikuni correctly.

Thefonz · 05-25-2017, 06:19 PM

So a couple weeks ago I received my 2017 taotao rhino 250 and right from the gate I loved it for a whopping $1000. I have since added a winch to the front, I am in the process of doing 2LZ's rear hitch idea. I have also swapped out carbs, I have changed to the mikuni vm26 clone and I am currently running a 115 main and a 35 pilot. I have had the size 20 pilot in it and also a 30 size pilot in it. I just today put in a 35 as I thought I was running too lean. Here is my issue.

This quad revs ridiculously high. I have it tuned enough so that I can ride this thing and it is excellent with lots of power, but if I pull in the clutch or put it in neutral, the RPMS soar. I have tried the mixture screw in 1-2-3-4-5-5 even 7 turns and it isn't helping. I have messed around with the needle and changed the slider to every position. I am at a complete loss. I have a K&N style filter on it and I'm starting to think that I'm just pulling too much air for the little carb and motor. I have messed with the idle screw as well and that doesn't help. I'm just at a loss. The only other symptoms I have had, which I "think" I have fixed, is that between idle and 1/4 throttle, I would have some light backfire type issues, hence why I jumped from the 30-35 pilot. I think that has MOSTLY solved that issue. Other than that, I'm lost. I don't know what I'm running, be it lean or rich, when I check the plug it looks good. Any help would be great.

Mudflap · 05-25-2017, 07:27 PM

Any chance of an air leak between the carb and head? An O ring out of place or missing?

Darth Racer · 05-25-2017, 07:38 PM

I had the high revving on mine. Had to cut about a 1/4" off of the throttle cable. Some others have had an issue with the cable getting twisted when they screwed the cap on the needle. If you hold the cable in position while you screw the cap back on it may resolve it... if not you have to carefully cut back some of the shielding to make the cable body shorter.

Basically the cable is forcing the needle and slide to be more open at rest position. The slide when no throttle applied should bottom out in the carb.

Thefonz · 05-25-2017, 08:01 PM

I don't think I'm dealing with an air leak. I could be wrong as I haven't checked it, but it seems unlikely as the quad is only a couple weeks old and it was fine prior to the mikuni switch. I should still check and will as soon as I pick up some starter fluid. I will also check out the cable tomorrow first thing. I feel like that may be a likely scenario, especially since the screw for idle adjustment doesn't do anything when I use it. Thanks guys

david3921 · 05-25-2017, 11:07 PM

I'm with Darth as this has happened before...to me as well. The cable didn't seat all the way at the cap. I ended up using the original cap and all was good. Try checking the position of the slide bottom with no cable versus with it connected.

rwl6935 · 05-26-2017, 07:55 AM

If it's not a throttle cable issue the 35 pilot may be letting too much fuel passed the adjustment needle. Go to a slightly smaller jet to test this theory if all else fails.

beyondhonesty · 05-26-2017, 12:21 PM

Check the spark plug... I've never changed the jets with my clone carb, could I be missing out?

Thefonz · 05-26-2017, 03:16 PM

I have re tightened the cap while making sure that the throttle cable was held and that seems to have helped immensely. I am still a little high on idle, but after a little tinkering with the mixture screw I suspect that I will have the idle set. The rhino runs so good. Ow with the new jets do I would assume you may be missing out on some extra power but I'm not sure. They are cheap enough that it may not hurt to just try the usual 115 main and 30 pilot that everyone seems pretty agreed upon in this forum. I for one am keeping the 35 as it did take away my slight backfire/half boggy feeling between idle and 1/4 throttle. I also finished the hitch setup today and it looks great. A little sloppy welding job for the plate since I didn't bolt that part, but it's strong and will definitely pull th trailer around.

Darth Racer · 05-26-2017, 03:52 PM

Pictures or it never happened... We like pictures.

Thefonz · 05-28-2017, 09:39 AM

Bad photo, I'll get better ones later.

Darth Racer · 05-28-2017, 07:36 PM

Looks good

Weldangrind · 05-29-2017, 12:46 PM

For troubleshooting purposes, a vacuum leak will typically present as a hanging idle; IOW, when you rev the engine, it takes longer than normal to return to idle, but it does come back down.

Thefonz · 06-02-2017, 04:49 PM

Hey,

So I was wondering if you guys would give me another opinion on my plug. I am having mixed feeling deciding if I am running lean or not still. Opinions?

Darth Racer · 06-02-2017, 08:43 PM

I looks okay too me. If anything closer to the rich side. If it was lean you would see more of a brownish heat burn.

If you do another test you have to use a new spark plug... keep that one you pulled as a spare.

05-25-2017, 06:19 PM	#1
Thefonz Join Date: May 2017 Posts: 5	TAOTAO 250 Rhino - Can't tune Mikuni correctly. So a couple weeks ago I received my 2017 taotao rhino 250 and right from the gate I loved it for a whopping $1000. I have since added a winch to the front, I am in the process of doing 2LZ's rear hitch idea. I have also swapped out carbs, I have changed to the mikuni vm26 clone and I am currently running a 115 main and a 35 pilot. I have had the size 20 pilot in it and also a 30 size pilot in it. I just today put in a 35 as I thought I was running too lean. Here is my issue. This quad revs ridiculously high. I have it tuned enough so that I can ride this thing and it is excellent with lots of power, but if I pull in the clutch or put it in neutral, the RPMS soar. I have tried the mixture screw in 1-2-3-4-5-5 even 7 turns and it isn't helping. I have messed around with the needle and changed the slider to every position. I am at a complete loss. I have a K&N style filter on it and I'm starting to think that I'm just pulling too much air for the little carb and motor. I have messed with the idle screw as well and that doesn't help. I'm just at a loss. The only other symptoms I have had, which I "think" I have fixed, is that between idle and 1/4 throttle, I would have some light backfire type issues, hence why I jumped from the 30-35 pilot. I think that has MOSTLY solved that issue. Other than that, I'm lost. I don't know what I'm running, be it lean or rich, when I check the plug it looks good. Any help would be great.
	0

05-25-2017, 11:07 PM	#5
david3921 Join Date: Feb 2009 Location: Michigan Posts: 1,030	I'm with Darth as this has happened before...to me as well. The cable didn't seat all the way at the cap. I ended up using the original cap and all was good. Try checking the position of the slide bottom with no cable versus with it connected. __________________ 2012 Kawasaki Versys 1984 Honda Magna V65 2016 Rhino 250 2016 Tao Tao 125D
	1

05-26-2017, 12:21 PM	#7
beyondhonesty Join Date: Apr 2017 Posts: 20	Check the spark plug... I've never changed the jets with my clone carb, could I be missing out? __________________ 12/2016 Rhino 250
	0

05-29-2017, 12:46 PM	#12
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	For troubleshooting purposes, a vacuum leak will typically present as a hanging idle; IOW, when you rev the engine, it takes longer than normal to return to idle, but it does come back down. __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
	0

05-25-2017, 07:27 PM	#2
Mudflap Join Date: Sep 2014 Posts: 1,870	Any chance of an air leak between the carb and head? An O ring out of place or missing?
	0

05-25-2017, 07:38 PM	#3
Darth Racer Join Date: Apr 2016 Location: MD Posts: 558	I had the high revving on mine. Had to cut about a 1/4" off of the throttle cable. Some others have had an issue with the cable getting twisted when they screwed the cap on the needle. If you hold the cable in position while you screw the cap back on it may resolve it... if not you have to carefully cut back some of the shielding to make the cable body shorter. Basically the cable is forcing the needle and slide to be more open at rest position. The slide when no throttle applied should bottom out in the carb.
	0

05-25-2017, 08:01 PM	#4
Thefonz Join Date: May 2017 Posts: 5	I don't think I'm dealing with an air leak. I could be wrong as I haven't checked it, but it seems unlikely as the quad is only a couple weeks old and it was fine prior to the mikuni switch. I should still check and will as soon as I pick up some starter fluid. I will also check out the cable tomorrow first thing. I feel like that may be a likely scenario, especially since the screw for idle adjustment doesn't do anything when I use it. Thanks guys
	0

05-26-2017, 07:55 AM	#6
rwl6935 Join Date: Mar 2017 Posts: 203	If it's not a throttle cable issue the 35 pilot may be letting too much fuel passed the adjustment needle. Go to a slightly smaller jet to test this theory if all else fails.
	0

05-26-2017, 03:16 PM	#8
Thefonz Join Date: May 2017 Posts: 5	I have re tightened the cap while making sure that the throttle cable was held and that seems to have helped immensely. I am still a little high on idle, but after a little tinkering with the mixture screw I suspect that I will have the idle set. The rhino runs so good. Ow with the new jets do I would assume you may be missing out on some extra power but I'm not sure. They are cheap enough that it may not hurt to just try the usual 115 main and 30 pilot that everyone seems pretty agreed upon in this forum. I for one am keeping the 35 as it did take away my slight backfire/half boggy feeling between idle and 1/4 throttle. I also finished the hitch setup today and it looks great. A little sloppy welding job for the plate since I didn't bolt that part, but it's strong and will definitely pull th trailer around.
	1

05-26-2017, 03:52 PM	#9
Darth Racer Join Date: Apr 2016 Location: MD Posts: 558	Pictures or it never happened... We like pictures.
	3

05-28-2017, 07:36 PM	#11
Darth Racer Join Date: Apr 2016 Location: MD Posts: 558	Looks good
	0

06-02-2017, 08:43 PM	#14
Darth Racer Join Date: Apr 2016 Location: MD Posts: 558	I looks okay too me. If anything closer to the rich side. If it was lean you would see more of a brownish heat burn. If you do another test you have to use a new spark plug... keep that one you pulled as a spare.
	0