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#1 |
Join Date: Sep 2022
Posts: 6
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Boom vader dieing after riding please help
So i bought a boom vader around 2 months back and havent had the best experience. Out the box i changed the oil, carb, and sprocket. I didnt clean the gas tank or replace the fuel line (I will probable replace fuel line soon).
Problem is, the bike starts when it feels like it and on a good day itll drive for like 30 minutes, then starts jerking, dieing and not starting anymore. then a few minutes later it might start again for like 5 minutes. I already replaced the battery and spark plug. the spark plug got dark as hell for 50 miles. Im new to bikes and carbs so if someone could please help id appreciate it a lot. |
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#2 |
Join Date: Sep 2021
Location: De Soto, MO
Posts: 1,918
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Check the valve clearances. You want approximately .06 - .07 mm, or .0025" - .003". Exhaust valves always run a little hotter than intake, so if anything they should have a larger gap. Chinese bikes are notorious for having valve clearances too tight from the factory, causing overheating of the head.
Edit: Overall I agree with 4T_Goblin's post below. Intake .003"/.08 mm. Exhaust I'd go with .004"/.10 mm. These are the recommendations for Lifan's new KPX. Before the KPX they said .06 mm for both valves on the X-pect for instance, and you would often find them from the factory much tighter than that even, like .02 mm, and require immediate adjustment. Finally they are getting their act together with valve clearances. Any time you get your hands on a Chinese bike, check valve clearance so you have a baseline for troubleshooting. IMO .005"/.13 mm might be a little too loose, since the exhaust valve will not be opening as far. That also contributes to heat buildup, and a bit of power loss due to inefficient exhaust breathing. So the trick is to find the happy medium for valve clearances. For me that would be .08 mm intake and .10 mm exhaust. However, it depends on how hot the individual bike runs, so maybe for 4T_Goblin this is proper. AFAIK, no one in the history of the universe has ever gotten a burned intake valve, because the fuel coming in cools off the valve. But the hot expended gases exiting thru the exhaust valve heats it up, so it is more important to make sure its clearance is not too tight or too loose. If the clearance is too tight, then as the exhaust valve stem heats up and lengthens, the valve does not fully seat and you lose power. If it's too loose, then it does not open enough, and the hot gases can't fully leave the combustion chamber. Screwed either way. The intake side is less critical. As far as the dark plug goes, your replacement carb is running too rich. There is plenty of info on here and YT for tuning carbs.
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2021 Lifan Xpect--sold 2022 Lifan KPX 1972 Honda CT90--The Carrot 1969 Honda CT90--The Tomahto Cheesy is the WDK (workplace drama king). Now retired. Nope, back in the saddle. Climate: The Movie https://www.youtube.com/watch?v=A24fWmNA6lM How our government really works https://www.youtube.com/watch?v=QjadCd0VRBw Question all authority.....think for yourself Last edited by TominMO; 09-20-2022 at 08:20 AM. |
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#4 |
Join Date: Aug 2019
Location: Bay City, MI
Posts: 398
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Sounds like the common issue these have with the fuel tank vent line being pinched. Check it under the left side plastics.
Another way to verify if this is the issue, after it stumbles and dies (sounds like fuel starvation), is to then open the fuel cap, give it a minute to refill the float bowl, and see if it re-starts and runs normally. if so, fuel tank vent line is pinched and plugged. |
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#5 |
Join Date: Sep 2022
Posts: 6
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Do you have a guide or video on how to do a valve adjustment on these? I know how to do them on cars but im sure its not the same at all lol.
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#6 |
Join Date: Jan 2021
Location: Lehigh Valley Area
Posts: 159
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People are using the word 'vapor lock' when it's actually a vaccum being drawn in the gas tank from improper venting.
Ride the bike and when it starts acting up, quickly stop the bike pop the gas cap and see if that elevates the problems. https://mymotorcycleblog.com/boom-va...-lock-no-fuel/ Or just due what we all do. Upgrade the carb and manually fix the venting problem. ![]() https://mymotorcycleblog.com/boom-va...cc-grom-clone/ Tom
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- My 3 Bikes: 1. TaoTao TBR7 (My TBR7 Upgrades) 2. Boom Vader (FYI: My Boom Vader Upgrades) 3. 1978 Suzuki SG750 --------------------------------------------- Testing a YouTube Channel ![]() |
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#7 | |
Join Date: Sep 2021
Location: De Soto, MO
Posts: 1,918
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Quote:
Edit: Couldn't resist. I like this guy:
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2021 Lifan Xpect--sold 2022 Lifan KPX 1972 Honda CT90--The Carrot 1969 Honda CT90--The Tomahto Cheesy is the WDK (workplace drama king). Now retired. Nope, back in the saddle. Climate: The Movie https://www.youtube.com/watch?v=A24fWmNA6lM How our government really works https://www.youtube.com/watch?v=QjadCd0VRBw Question all authority.....think for yourself |
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#8 |
Join Date: Sep 2022
Posts: 6
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popping the gas cap might have solved the issue. i will try more some other day.
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#9 |
Join Date: Sep 2022
Posts: 6
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Thanks a lot man. once ill test if it is because of the gas tank while im waiting for the adjuster tool, if its not due to that ill use those videos and adjust the valves. (unless you suggest to adjust valves regardless?
Last edited by aaa; 09-20-2022 at 09:13 PM. |
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#10 | |
Join Date: Aug 2019
Location: Bay City, MI
Posts: 398
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Quote:
I'd test the fuel tank vent issue now.. just so you know or not. |
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#11 |
Join Date: Sep 2022
Posts: 6
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Ah found the issue. When I was deleting the old carb system I plugged up the vent tube with a screw. My valve adjustment tools come tomorrow so I'm going to do that. Someone said I'm running rich that's why my spark plugs are caked with carbon, how do I tune my carb properly? I'm not able to tune it while the bike is running cause the adjustment valve sits on the bottom of the carb which is where the head is.
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#12 | |
Join Date: Sep 2021
Location: De Soto, MO
Posts: 1,918
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Quote:
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2021 Lifan Xpect--sold 2022 Lifan KPX 1972 Honda CT90--The Carrot 1969 Honda CT90--The Tomahto Cheesy is the WDK (workplace drama king). Now retired. Nope, back in the saddle. Climate: The Movie https://www.youtube.com/watch?v=A24fWmNA6lM How our government really works https://www.youtube.com/watch?v=QjadCd0VRBw Question all authority.....think for yourself |
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#13 |
Join Date: Sep 2022
Posts: 6
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Lol my air fuel adjustment is on the bottom I think. Last couple of times I tried tuning the carb I have to remove the carb adjust then put back. Tedious.
Carb in question https://a.co/d/1HuFPCk |
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#14 | |
Join Date: Sep 2021
Location: De Soto, MO
Posts: 1,918
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Quote:
The screw on the bottom lets you drain gas out of the float bowl. See what looks like a little brass BB embedded in the body? And above that, a brass tube. The tube is for gas going in from the tank, and the brass BB looks like what you need to drill out to access the air/fuel mixture screw.
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2021 Lifan Xpect--sold 2022 Lifan KPX 1972 Honda CT90--The Carrot 1969 Honda CT90--The Tomahto Cheesy is the WDK (workplace drama king). Now retired. Nope, back in the saddle. Climate: The Movie https://www.youtube.com/watch?v=A24fWmNA6lM How our government really works https://www.youtube.com/watch?v=QjadCd0VRBw Question all authority.....think for yourself |
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#15 | |
Moderator
Join Date: Oct 2016
Location: Houma, La.
Posts: 11,656
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Quote:
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Tags |
boom, vader |
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