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Backfiring
by: jerseyboy - Dec 30, 2014 20:33:32 GMT -5
Post by jerseyboy on Dec 30, 2014 20:33:32 GMT -5
Are you sure its timed correctly? It wont backfire from oil and gas buildup in the exhaust,,there is air coming in from somewhere,,what about the carb and the ACV valve,,is it working correctly? I agree with Alley about he exhaust also,,check and make sure its tight with two studs,new gasket,,make sure to tighten it down nice and snug equally on both nuts...I check my exhaust nuts every time I change my oil which is every 1000km..I know its over kill but I like clean oil in my motors:) BTW-That video should be deleted from the net,,its a waste of server space IMO. Much better ones out there to check out. The video above is me showing tvnacman that the cam is TDC as well as the flywheel because he said he wanted to see it. It isn't an instructional video. As you can see as well these things are what does the timing right? These are all setup properly, right? So the timing is correct? I poured carb cleaner into my muffler pipe from the end that connects to the engine, and nothing came out of the end of the muffler... What? I tried pouring some in the end to see if it would come out the other end that connects to the engine, it didn't. Is this because the catalytic converter converts it before it passes through? It still smells like carb cleaner, and I got my hands on a vacuum and blew air into it, and it came out the other end and wreaked like carb cleaner and made me dizzy. I'm so sorry brother,,I thought it was a video you found of somebody showing how to set up the cam gear..lol..next time I need to read the whole thread first,,Im truly sorry for bashing the video bro...the gear looked perfect,,but the flywheel has to be at the TDC mark as well.. There is a few baffles in the muffler if its a factory one,,the cleaner or fluid will have a hard time making it out the other end unless you really fill it up and shake it good..the carb cleaner prolly evaporated as it does that pretty fast...you will be fine Tom |
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Backfiring
by: lain - Dec 30, 2014 21:49:06 GMT -5
Post by lain on Dec 30, 2014 21:49:06 GMT -5
The video above is me showing tvnacman that the cam is TDC as well as the flywheel because he said he wanted to see it. It isn't an instructional video. As you can see as well these things are what does the timing right? These are all setup properly, right? So the timing is correct? I poured carb cleaner into my muffler pipe from the end that connects to the engine, and nothing came out of the end of the muffler... What? I tried pouring some in the end to see if it would come out the other end that connects to the engine, it didn't. Is this because the catalytic converter converts it before it passes through? It still smells like carb cleaner, and I got my hands on a vacuum and blew air into it, and it came out the other end and wreaked like carb cleaner and made me dizzy. I'm so sorry brother,,I thought it was a video you found of somebody showing how to set up the cam gear..lol..next time I need to read the whole thread first,,Im truly sorry for bashing the video bro...the gear looked perfect,,but the flywheel has to be at the TDC mark as well.. There is a few baffles in the muffler if its a factory one,,the cleaner or fluid will have a hard time making it out the other end unless you really fill it up and shake it good..the carb cleaner prolly evaporated as it does that pretty fast...you will be fine Tom It's no prob, it wasn't pro looking video or anything lol, I was just doing it for reference and as you can see I just got everything put together pretty fast after I figured out how to position my hands lol. I've checked the cam and chain a couple dozen times so it's like second nature to me to just pop it in and it's already on TDC. The flywheel I kept still using a wound up wire to prevent any movement. It didn't allow it to move at all while doing the process. It seems to be running better now, I let the muffler dry out for a few hours. I started it up and there was near to no smoke, just steam from it being 20 degrees tonight. It DOES however backfire during warmup still, I fixed the autochoke/enricher but during the first 1-2 mins before it kicks in fully it seems to backfire like once or twice while warming up. Does this sound liek maybe the idle jet is slightly too big or would jetting the main jet down to maybe  from  help? |
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Backfiring
by: lain - Dec 30, 2014 21:53:58 GMT -5
Post by lain on Dec 30, 2014 21:53:58 GMT -5
White smoke is gas, dark smoke is oil. It's starts out smoking white but quits? I'd suspect it's way too rich and the auto-enricher sends it over the cliff. When the enricher shuts off it comes back down out of the stratosphere but is still too rich. Maybe I missed it but what is your jet now? Do you have a Uni or what? How did you set the A/F screw? It's true if your muffler is blocked it could cause problems. John is correct, gas is a solvent for oil and gas residue, it will dissolve a lot of the crap in there and you may be able to dump it out. Wet oily black plug is way too rich bro. I can't figure out what is makign it rich exactly. I have a stock CVK carb, it has the stock idle jet, which I have no clue what size it is, and a main jet # I got with my BBK. My carb does not have a mixture screw, or at least it does not have one I can get to. It has a brass cap over it blocking the hole up. |
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Post by JerryScript on Dec 30, 2014 23:11:08 GMT -5
You need to remove the brass plug over your air/fuel mixture screw. It's very easy. Take a 1/8" drill and slowly drill into it. Often, just drilling into it will remove it, but don't apply much pressure, you don't want to damage the a/f screw head when you push though. If not, put a sheet metal screw in it, and once snug, pull it out.
You are not going to be able to get your scooter tuned up right until you can adjust the a/f mixture.
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Post by lain on Dec 31, 2014 1:26:29 GMT -5
You need to remove the brass plug over your air/fuel mixture screw. It's very easy. Take a 1/8" drill and slowly drill into it. Often, just drilling into it will remove it, but don't apply much pressure, you don't want to damage the a/f screw head when you push though. If not, put a sheet metal screw in it, and once snug, pull it out. You are not going to be able to get your scooter tuned up right until you can adjust the a/f mixture. How do I remove it without a drill? |
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Backfiring
by: tvnacman - Dec 31, 2014 7:27:50 GMT -5
Post by tvnacman on Dec 31, 2014 7:27:50 GMT -5
Lain , pack that scooter in a mini van , pick up or on a trailer and drive the 4 hours to NYC . Bring your friend and a camera . Will straighten out that Chines make it run straight .
John
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Backfiring
by: lain - Dec 31, 2014 10:39:57 GMT -5
Post by lain on Dec 31, 2014 10:39:57 GMT -5
I wish it were that easy tvnacman, but if I had something to carry/tow the scoot in I wouldn't need the scoot haha. Not to say I wouldn't still ride, cuz scoots are fun. So I went out for a ride today, let it warm up, it backfired once during the warmup while it was smoking, then when I initially gave it throttle it started to bog down so I let off the throttle and it went back to idle, then a few seconds later I gave it throttle and it backfired out of the end of the muffler then started to take off and did not backfire anymore. The ride was about half a mile to the town square then back in about 10-15 mins. |
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Backfiring
by: alleyoop - Dec 31, 2014 10:46:57 GMT -5
Post by alleyoop on Dec 31, 2014 10:46:57 GMT -5
Well start saving your money cause you are going to need more parts if you do not fix the backfiring.
Spend some bucks on a few needed tools and or borrow a drill and a 1/8 drill bit.
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Backfiring
by: lain - Dec 31, 2014 11:01:12 GMT -5
Post by lain on Dec 31, 2014 11:01:12 GMT -5
Well start saving your money cause you are going to need more parts if you do not fix the backfiring. Spend some bucks on a few needed tools and or borrow a drill and a 1/8 drill bit. I am trying to fix the backfiring... I mean we are 3 pages in here man I'm not posting just to annoy you guys, I need help, I am not as knowledgeable as you guys. Are you saying you think the backfiring could be resolved by adjusting the mixture screw that is behind the brass cap? |
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Backfiring
by: jerseyboy - Dec 31, 2014 11:13:08 GMT -5
Post by jerseyboy on Dec 31, 2014 11:13:08 GMT -5
If you are careful it can be picked out using a small flat head and or pick/awl type tool,,the drill works the best,,its just a small brass plug.The carbs are set so lean from factory...if the mixing screw isn't enough you need to up jet one size or so.
Slight backfiring under decel is not really a big deal,,mine does it all the time..lean is mean,,but too lean is bad cause of heat issues.You need to find the perfect balance or tune the air/fuel mixture to the motor.As long as you don't have any leaks anywhere,,the scoot should run good from factory with minor adjustments.
BTW-Could you make a quick video of it backfiring,,just put it on the center stand and rev it up to 5 or 6K RPM then let it drop,,so we can hear it,,might just be normal or slightly out of tune,,prolly nothing to worry about,,if its backfiring under accel then you most likely have an ignition issue.
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Backfiring
by: alleyoop - Dec 31, 2014 11:20:45 GMT -5
Post by alleyoop on Dec 31, 2014 11:20:45 GMT -5
Ok listen up, when do you get the Backfire(POW, like a gunshot) or is it a(POP) sound? Big difference some call a POP sounds backfires and they are not.
When you get the sound did you twist the throttle wide open? Will it make that sound if YOU EASE the throttle open to pick up speed. Or does it not matter it just makes the sound here and there at any throttle position.
Alleyoop
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Backfiring
by: lain - Dec 31, 2014 11:34:23 GMT -5
Post by lain on Dec 31, 2014 11:34:23 GMT -5
Ok listen up, when do you get the Backfire(POW, like a gunshot) or is it a(POP) sound? Big difference some call a POP sounds backfires and they are not. When you get the sound did you twist the throttle wide open? Will it make that sound if YOU EASE the throttle open to pick up speed. Or does it not matter it just makes the sound here and there at any throttle position. Alleyoop I will post a video soon so you can see/here yourself. It pops, it does not POW, there is a difference? I thought it was just a smaller backfire? Basically it'll pop once or twice during warmup, then it'll bog on initial throttle after warmup and pop loudly but not as loud as a gunshot then it is fine till next time I have to warm up. |
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Backfiring
by: lain - Dec 31, 2014 11:36:14 GMT -5
Post by lain on Dec 31, 2014 11:36:14 GMT -5
If you are careful it can be picked out using a small flat head and or pick/awl type tool,,the drill works the best,,its just a small brass plug.The carbs are set so lean from factory...if the mixing screw isn't enough you need to up jet one size or so. Slight backfiring under decel is not really a big deal,,mine does it all the time..lean is mean,,but too lean is bad cause of heat issues.You need to find the perfect balance or tune the air/fuel mixture to the motor.As long as you don't have any leaks anywhere,,the scoot should run good from factory with minor adjustments. BTW-Could you make a quick video of it backfiring,,just put it on the center stand and rev it up to 5 or 6K RPM then let it drop,,so we can hear it,,might just be normal or slightly out of tune,,prolly nothing to worry about,,if its backfiring under accel then you most likely have an ignition issue. It does not happen during decel, only during warmup and initial throttle right after warmup. BTW backfiring, or popping, started after BBK install a couple months ago. Just replaced the head because the exhaust valve and one of the studs for the exhaust pipe were damaged/missing. Video soon. |
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Backfiring
by: jerseyboy - Dec 31, 2014 13:37:13 GMT -5
Post by jerseyboy on Dec 31, 2014 13:37:13 GMT -5
Oh,,cool..I bet your issue will be gone after you get the new head on there with two exhaust bolts snugged up right.
A good tuned motor will pop some on the decel..totally normal..alot of times you wont even hear it unless you have a free flowing pipe.
Will be standing by.
Tom
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Backfiring
by: lain - Dec 31, 2014 13:41:03 GMT -5
Post by lain on Dec 31, 2014 13:41:03 GMT -5
It does not happen during decel, only during warmup and initial throttle right after warmup. BTW backfiring, or popping, started after BBK install a couple months ago. Just replaced the head because the exhaust valve and one of the studs for the exhaust pipe were damaged/missing. Video soon. Oh,,cool..I bet your issue will be gone after you get the new head on there with two exhaust bolts snugged up right. Will be standing by. Tom Not sure if I am speaking English wrong, but people on this forum keep misunderstanding me. Not sure why. I'm not trying to be rude, I just seriously feel like I may be speaking wrong now, I have language issues and so I cannot tell if I am saying things wrong or I am just being misunderstood. |
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help?
..BAD TO THE BONE..