Taotao wont run right after changing carbs and wont run right on original carb either

Cracklife94 · 05-05-2020, 11:30 AM

I bought a vm26 mikuni carb for my taotao tbr7 250cc, I tried a 115 main jet at first and it greatly improved power and made it do 70mph with my 280lb ass on it, but when it was at an idle and you revved it very quickly it would bog out so I adjusted the air mixture screw a few times, adjusted the idler needle a few times, and used a few different main jets. I found what seemed like the best combo but it still would bog if you hit the gas really quick when it was in neutral or at a stop. I think it may need a different pilot jet it has a 40 in it or something like that. But then I rode it a bit and it was great but now it keeps not wanting to start and then it runs awesome for a minute and then starts to bog down and dies then I cant get it started again. I even put the old carb back on and it is doing the same thing. Did I damage the engine possibly? Or could a dead battery somehow contribute to this?

**JerryHawk250** · 05-05-2020, 11:38 AM

40 is too big. On a Mikuni a 25 or 27.5 will be about right.

Cracklife94 · 05-05-2020, 11:43 AM

Could that be why it is dying while riding?

Goob · 05-05-2020, 11:55 AM

Quote:

Originally Posted by JerryHawk250

40 is too big. On a Mikuni a 25 or 27.5 will be about right.

I ended up with a 30 Pilot on my RXB150 (Mikuni VM26 Flange mount). I am at 5280 ft, so it seems like I should have had to go leaner, but this is what made it start well and idle steady. 1-1/4 turns out. I suppose this would translate a bit different to a 250 (but this little 150 is almost 14 hp...so maybe not that much different).

Bcole801 · 05-05-2020, 12:23 PM

I just had the same symptoms on my bike. Turned out the grounding wire was making intermittent contact and the coil where it was mounted to the frame was painted and wasn't making a good ground. Once I fixed those 2 issues, the bike runs great.

Cracklife94 · 05-05-2020, 01:23 PM

My altitude is 1167ft above sea level, my air mixture screw is out 2 turns, I have a 115 main and 40 pilot jet. I'm ordering smaller pilot jets today but I only have a main jet kit at the moment. The thing that stumps me is I put the original carb back on that had been working and now that carb doesn't work either so I don't understand what I did to it.

Cracklife94 · 05-05-2020, 01:25 PM

I mean it starts with either carb on but it bogs and often dies at low speeds and it was running pretty decent yesterday with the same settings on the new carb just a light bog if you revved to quick in neutral. Now it's a heavy bog at any low speed and wants to die at a stop.

alex_in_az · 05-05-2020, 07:59 PM

Quote:

Originally Posted by Cracklife94

I mean it starts with either carb on but it bogs and often dies at low speeds and it was running pretty decent yesterday with the same settings on the new carb just a light bog if you revved to quick in neutral. Now it's a heavy bog at any low speed and wants to die at a stop.

this sounds a lot like my TBR7 problems, turned out it was the CDI unit. it was fine when cold, but when it warmed up it wouldn't idle below about 4k rpm without dying on me and being a stone bitch to re-start

kingofqueenz · 05-05-2020, 08:31 PM

Quote:

Originally Posted by Cracklife94

made it do 70mph with my 280lb

I'm sorry...did you say 70mph???

What other mods do you have beyond the carb?

mtiberio · 05-05-2020, 09:03 PM

Sounds like the problem is not the carb

05-05-2020, 11:30 AM	#1
Cracklife94 Join Date: Mar 2020 Posts: 18	Taotao wont run right after changing carbs and wont run right on original carb either I bought a vm26 mikuni carb for my taotao tbr7 250cc, I tried a 115 main jet at first and it greatly improved power and made it do 70mph with my 280lb ass on it, but when it was at an idle and you revved it very quickly it would bog out so I adjusted the air mixture screw a few times, adjusted the idler needle a few times, and used a few different main jets. I found what seemed like the best combo but it still would bog if you hit the gas really quick when it was in neutral or at a stop. I think it may need a different pilot jet it has a 40 in it or something like that. But then I rode it a bit and it was great but now it keeps not wanting to start and then it runs awesome for a minute and then starts to bog down and dies then I cant get it started again. I even put the old carb back on and it is doing the same thing. Did I damage the engine possibly? Or could a dead battery somehow contribute to this?
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05-05-2020, 11:38 AM	#2
JerryHawk250 Moderator Join Date: Oct 2016 Location: Houma, La. Posts: 11,707	40 is too big. On a Mikuni a 25 or 27.5 will be about right. __________________ 2024 Linhai 300 ATV 4x4 2023 Lifan Lycan 250 Chopper 2023 Venom Evader 2022 Lifan KPX250 2020 Kawasaki Vulcan S (Sold) 2004 Honda ST 1300 2016 Black Hawk 250 (sold) Keihin PE30 carb,125 main,38 slow.Pod filter,ported & decked head 10:1 CR,Direct Ignition Coil,15/40Sprockets,NGK DPR8EIX-9,De-Cat,Dual Oil Cooler,Digital Cluster 2016 Cazador180 XL 2014 Coolster150 JerryHawk250.com My YouTube Channel
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05-05-2020, 01:23 PM	#6
Cracklife94 Join Date: Mar 2020 Posts: 18	1167ft altitude My altitude is 1167ft above sea level, my air mixture screw is out 2 turns, I have a 115 main and 40 pilot jet. I'm ordering smaller pilot jets today but I only have a main jet kit at the moment. The thing that stumps me is I put the original carb back on that had been working and now that carb doesn't work either so I don't understand what I did to it.
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05-05-2020, 09:03 PM	#10
mtiberio Join Date: Jun 2016 Location: Arlington, VA Posts: 258	Sounds like the problem is not the carb __________________ 4 time WERA SuperVintage Roadracing National Champion, SCTA Land Speed Record Holder, 3rd AMA Motorcycle GP of Miami
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05-05-2020, 11:43 AM	#3
Cracklife94 Join Date: Mar 2020 Posts: 18	Could that be why it is dying while riding?
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05-05-2020, 12:23 PM	#5
Bcole801 Join Date: Sep 2019 Posts: 4	I just had the same symptoms on my bike. Turned out the grounding wire was making intermittent contact and the coil where it was mounted to the frame was painted and wasn't making a good ground. Once I fixed those 2 issues, the bike runs great.
	0

05-05-2020, 01:25 PM	#7
Cracklife94 Join Date: Mar 2020 Posts: 18	I mean it starts with either carb on but it bogs and often dies at low speeds and it was running pretty decent yesterday with the same settings on the new carb just a light bog if you revved to quick in neutral. Now it's a heavy bog at any low speed and wants to die at a stop.
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