Boom vader dieing after riding please help

aaa · 09-19-2022, 09:38 PM

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.

TominMO · 09-19-2022, 10:26 PM

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.

aaa · 09-20-2022, 07:18 PM

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.

TominMO · 09-20-2022, 08:37 PM

Quote:

Originally Posted by aaa

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.

Same idea as cars. Do a YT search on adjusting motorcycle valves and watch several. One critical thing that you can get wrong is using the wrong TDC. Other than that it is pretty straightforward.

Edit: Couldn't resist.

I like this guy:

aaa · 09-20-2022, 09:29 PM

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?

Deckard_Cain · 09-21-2022, 10:31 AM

Quote:

Originally Posted by aaa

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?

I'd always check and adjust valves on a new engine, or check them on one that is experiencing improper running symptoms. Once they're within spec, you shouldn't need to check them for quite a while.. a couple thousand miles usually.

I'd test the fuel tank vent issue now.. just so you know or not.

aaa · 09-22-2022, 10:48 AM

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.

TominMO · 09-22-2022, 11:07 AM

Quote:

Originally Posted by aaa

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.

That's more likely a drain on the bottom of the float bowl. Don't know of any way to adjust a carb from there. The jets are inside, after you remove the float bowl. There's about a zillion YT vids on adjusting motorcycle carbs. Do a search, and watch several. The air/fuel adjustment screw will be on the side somewhere. Possibly under a cover you would have to drill out, very easy. Watch videos.

4T_Goblin · 09-20-2022, 08:44 AM

Check all vents are functioning properly. Did you delete the egr system? Are you sure the carb is tuned correctly?

I run my valves at .003" and .005".

Deckard_Cain · 09-20-2022, 10:51 AM

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.

CheapThrills · 09-20-2022, 08:32 PM

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

aaa · 09-20-2022, 09:27 PM

popping the gas cap might have solved the issue. i will try more some other day.

TominMO · 09-22-2022, 03:32 PM

Ouch! That tool costs as much as the carb. The 90 degree ratchet would be far better, if it fits in there width-wise. Here is a much better-looking set. The 41-piece version has both long and short bits. Once in a while tools like these are very handy to have lying around.
https://www.amazon.com/TOMMARS-102-P...7&sr=8-25&th=1

I have this cheapo from Harbor Freight. Might do the job as is, or might need a longer bit.
https://www.harborfreight.com/8-piec...ver-92630.html

**JerryHawk250** · 09-22-2022, 03:38 PM

Quote:

Originally Posted by TominMO

Ouch! That tool costs as much as the carb. The 90 degree ratchet would be far better, if it fits in there width-wise. Here is a much better-looking set. The 41-piece version has both long and short bits. Once in a while tools like these are very handy to have lying around.
https://www.amazon.com/TOMMARS-102-P...7&sr=8-25&th=1

There are cheaper versions of it. https://www.amazon.com/dp/B09STJRP67...NsaWNrPXRydWU=

dirtbkr188 · 09-22-2022, 03:45 PM

On the Mikuni-clone VM22/26 carb, it is a fuel adjustment screw under the intake and in front of the float bowl. It is turned IN to lean the fuel mixture, and turned OUT to richen the mixture. The idle adjustment screw is located on the right side of the carb, as mounted on the manifold/engine.
THIS is the replacement fuel screw for the PITA stock one.

09-19-2022, 09:38 PM	#1
aaa Join Date: Sep 2022 Posts: 6	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.
	0

09-19-2022, 10:26 PM	#2
TominMO Join Date: Sep 2021 Location: De Soto, MO Posts: 1,976	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. __________________ 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. Nope, finally retired. 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 09:20 AM.
	1

09-20-2022, 09:29 PM	#5
aaa Join Date: Sep 2022 Posts: 6	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 10:13 PM.
	1

09-20-2022, 08:44 AM	#9
4T_Goblin Join Date: Jun 2021 Posts: 255	Check all vents are functioning properly. Did you delete the egr system? Are you sure the carb is tuned correctly? I run my valves at .003" and .005". __________________ 2020 Vader X-Pro X-7 2019 Kawasaki Ninja ex400 2022 Lifan KPX 250
	2

09-20-2022, 08:32 PM	#11
CheapThrills Join Date: Jan 2021 Location: Lehigh Valley Area Posts: 166	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 __________________ - 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
	1

09-20-2022, 07:18 PM	#3
aaa Join Date: Sep 2022 Posts: 6	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.
	0

09-22-2022, 10:48 AM	#7
aaa Join Date: Sep 2022 Posts: 6	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.
	0

09-20-2022, 10:51 AM	#10
Deckard_Cain Join Date: Aug 2019 Location: Bay City, MI Posts: 400	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.
	1

09-20-2022, 09:27 PM	#12
aaa Join Date: Sep 2022 Posts: 6	popping the gas cap might have solved the issue. i will try more some other day.
	0

09-22-2022, 03:32 PM	#13
TominMO Join Date: Sep 2021 Location: De Soto, MO Posts: 1,976	Ouch! That tool costs as much as the carb. The 90 degree ratchet would be far better, if it fits in there width-wise. Here is a much better-looking set. The 41-piece version has both long and short bits. Once in a while tools like these are very handy to have lying around. https://www.amazon.com/TOMMARS-102-P...7&sr=8-25&th=1 I have this cheapo from Harbor Freight. Might do the job as is, or might need a longer bit. https://www.harborfreight.com/8-piec...ver-92630.html __________________ 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. Nope, finally retired. 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
	0

09-22-2022, 03:45 PM	#15
dirtbkr188 Join Date: Aug 2009 Posts: 574	On the Mikuni-clone VM22/26 carb, it is a fuel adjustment screw under the intake and in front of the float bowl. It is turned IN to lean the fuel mixture, and turned OUT to richen the mixture. The idle adjustment screw is located on the right side of the carb, as mounted on the manifold/engine. THIS is the replacement fuel screw for the PITA stock one.
	1