two cycle scooter not pulling fuel from the carburetor into

[kj4spj]

two cycle scooter not pulling fuel from the carburetor into the engine .believe there's an air leak. going to do a air leak test on it and I will take pictures and show you what .I did it started spitting and sputtering couldn't get the carburetor tune properly and then one day just have any vacuum to the carburetor so I'm assuming I have a bad seal somewhere

[harleyracer59]

if you hold your hand over the carb inlet and crank it over, you should get gas on your palm. also if you get it started, and put your palm over carb inlet, it should die right out and get a little gas on your palm, if not, theres an air leak somewhere. let us know what you find

[chehystpewpur]

pull carb off and pull intake off its the 4 allen heads its really easy. there should be a metal coated v in there or a plastic v under the intake with the reeds in it. if they are missing thats most likely the culprit. if they are cracked chipped or they dont seal against the reed cage they need replaced. if those are good take the bowl off carb if fuel is in it your jets are most likely plugged or one of the passages is. if all is good there. take the exhaust off and try to fire the ole goat up. if you kick it a few times and it wakes up you most likely need an exhaust they go bad and will make 2 strokes do crazy things. if it still doesnt wake up the cylinder is toast and a circlip fell off the piston the rings wore out or its just time. a good cylinder usually lasts 3,000-5,000 miles before an overhaul is recommended. before you condemn the cylinder take the plug out and stick ur finger on the hole and seal it up well. slowly spin the motor over by hand and see if its making pressure and making strong vacuum aswell. not just the air displaced by the piston but actual compression 90 psi is a good number. if you cant tell or cant get a good seal tool stores will let you rent a compression tester for about 30-50 bux and you get that money back when you bring it back. plug up the spark plug hole with the right threaded fitting and hold the throttle wide open with the intake back on and the carb back on it. or carb off and the intake on and dont worry about the throttle. if the motor cant suck air in due to the throttle being closed if the carb is on the number will be lower or show a dead cylinder when its not actually bad. cant compress air that isnt there. report back finding and we go from there. thses things are cheap so even if you have a problem its usually 100 bux or less to fix.

[chehystpewpur]

almost forgot. if no fuel is in the carb to start with. check to make sure there is gas in it. atleast half tank. ive made this mistake many times. some tanks look like they have 1/3 tank but wont let any fuel out. some look half full and will have issues due to a clogged screen. top it off just incase always a safe bet when testing fuel problems. if good amount of fuel is in tank your tank screens could be clogged or plugged. or if you have an inline fuel filter those clog alot with 2 strokes. fuel filters are good for fuel its thin. 2 stroke oil is thick. once enough debris gets in there 2 stroke fuel wont flow well. and i believe it can crystallize when it dries out and break apart the filter and plug up even worse than regular gas would. if all of that is fine and you can blow through fuel line your vacuum line going from the intake to the fuel tank petcock is bad that will make it not flow fuel into the carb and sometimes just needs a good test to randomly work again. at 30,000 miles my stock one still works idk how but it sticks sometimes. suck and then blow into that line a few good times for about 3 seconds each way till you see fuel start flowing continue till line and filter fills and try to start. do you use the factory oil injection system or do you premix? the oil pumps also fail at random and will fry the piston rings and cause it to now have any compression.

[harleyracer59]

Jul 28, 2019 22:21:55 GMT -5 chehystpewpur said:

 do you use the factory oil injection system or do you premix? the oil pumps also fail at random and will fry the piston rings and cause it to now have any compression.

this is wrong and un true.  ive never seen or heard of one failing at random.  if oil tank is ran dry, that's operator fail. if ran dry and air bubbles/ air pockets are not bled from lines before restart, that too is operator fail.
  those little pumps are pretty bulletproof.  ive never even heard of a shaft failure. ive seen the shaft seal fail, even then pump still pumped. only issue was pump would leak oil into case. when sitting with engine off.  all that caused was occasional hard start and smoky warm ups..
  im still oil injected on all my 35 year old Hondas, all with big bores and bigger carbs.    
  a wise man once said "you only have to be 10% smarter than the object you are working with"

[aeroxbud]

Jul 29, 2019 15:44:08 GMT -5 harleyracer59 said:

Jul 28, 2019 22:21:55 GMT -5 chehystpewpur said:

 do you use the factory oil injection system or do you premix? the oil pumps also fail at random and will fry the piston rings and cause it to now have any compression.

this is wrong and un true.  ive never seen or heard of one failing at random.  if oil tank is ran dry, that's operator fail. if ran dry and air bubbles/ air pockets are not bled from lines before restart, that too is operator fail.
  those little pumps are pretty bulletproof.  ive never even heard of a shaft failure. ive seen the shaft seal fail, even then pump still pumped. only issue was pump would leak oil into case. when sitting with engine off.  all that caused was occasional hard start and smoky warm ups..
  im still oil injected on all my 35 year old Hondas, all with big bores and bigger carbs.    
  a wise man once said "you only have to be 10% smarter than the object you are working with"

You have seen one fail now! It was a bit Smokey for a couple of days. I left it at home for a couple. Then when I went to start it it had locked up. Oil pump had failed. And filled the cylinder, exhaust, and air box
IMG_20190617_115839 by aeroxpaul
Generally very reliable though. But not fool proof.

[harleyracer59]

Jul 30, 2019 4:53:22 GMT -5 aeroxbud said:

Jul 29, 2019 15:44:08 GMT -5 harleyracer59 said:

this is wrong and un true.  ive never seen or heard of one failing at random.  if oil tank is ran dry, that's operator fail. if ran dry and air bubbles/ air pockets are not bled from lines before restart, that too is operator fail.
  those little pumps are pretty bulletproof.  ive never even heard of a shaft failure. ive seen the shaft seal fail, even then pump still pumped. only issue was pump would leak oil into case. when sitting with engine off.  all that caused was occasional hard start and smoky warm ups..
  im still oil injected on all my 35 year old Hondas, all with big bores and bigger carbs.    
  a wise man once said "you only have to be 10% smarter than the object you are working with"

You have seen one fail now! It was a bit Smokey for a couple of days. I left it at home for a couple. Then when I went to start it it had locked up. Oil pump had failed. And filled the cylinder, exhaust, and air box
IMG_20190617_115839 by aeroxpaul
Generally very reliable though. But not fool proof.

I have seen this happen before.  that is caused by either the shaft seal or the check ball.  I mentioned the seal in my post but forgot about the check ball.  
   what I meant in previous post was, they don't dry up and fail randomly seizing the motor.  granted yours was hydro locked pretty good, but id take that any day over a seized piston from lack of lube.  all you really had to do was pull the plug and let it drain upside down...  lol  even then, you said you saw signs something was going south with the smoky start  ups.   
  you are right,  they are generally reliable, theyre not BULLET proof  and I haven't seen much that's fool proof.  fools can F up a wet dream..    
   but I still never seen one "randomly" dry up and seize a motor.  ive seen check balls leak, never seen one seize and stop flow though.    
  IMO  these are all redundant fail safes designed and built in by the manufactures.   the leak inward not outward.  if a seal or check ball fails, it over lubes the engine. not stop lubing.   
   I see people spreading  the " oil injection pumps fail all the time, you should go premix"  only because someone sold that person on this idea. 
my 55 Harley had a bad check ball  in the oil pump that would sump the engine after  a couple weeks   and when u started it it.  it would spray oil out of the  breather tube    and make the biggest messes.                           

[aeroxbud]

It's like the Piaggio engines. On the forums years ago, a lot of oil pumps were failing. But more often than not, from what I could see it was actually the drive belt for the pump snapping. Not the pump failing. Lack of maintenance.

[pitobread]

I've seen an oil pump on a dio fail and fill the motor up so much when I pulled the reed block off oil came out.

It happens more than people know, which is why I ditch them on the regular.

Old Yamaha RD stuff is notorious for working fine one day and locking the motor on the next, which is why a lot of guys nuke the pumps on those. It's simply another variable that could fail (everything mechanical eventually will fail given adequate time or strain)


People strive for better lubrication all the time, polishing oil galleys, high vol or high flow oil pumps. Because lubrication = cooling and cooling = happy engine on the limits. I'll take my 32:1 at 13k knowing if it melts it's not because of lubrication. Bad tuning or another variable sure.

[chehystpewpur]

Jul 29, 2019 15:44:08 GMT -5 harleyracer59 said:

Jul 28, 2019 22:21:55 GMT -5 chehystpewpur said:

 do you use the factory oil injection system or do you premix? the oil pumps also fail at random and will fry the piston rings and cause it to now have any compression.

this is wrong and un true.  ive never seen or heard of one failing at random.  if oil tank is ran dry, that's operator fail. if ran dry and air bubbles/ air pockets are not bled from lines before restart, that too is operator fail.
  those little pumps are pretty bulletproof.  ive never even heard of a shaft failure. ive seen the shaft seal fail, even then pump still pumped. only issue was pump would leak oil into case. when sitting with engine off.  all that caused was occasional hard start and smoky warm ups..
  im still oil injected on all my 35 year old Hondas, all with big bores and bigger carbs.    
  a wise man once said "you only have to be 10% smarter than the object you are working with"

well how about you tell these other people they dont fail and please tell a few of my cylinders they dont fail because guess what? its why i and many others premix. i bought my scoot with a bad pump. replaced more than i should have and gave up. brand new pump failed within a week. and the next one sheared the plastic pump gear aswell. the first one lasted a while but started dumping oil at the seam in the middle. i ended up finding a used mikuni one off craigslist and rocked it for a while but when it died that was it. yes some have good luck with them but parts are not what they used to be and defects are much more common. do what works for you but dont spread misinformation telling people something man made is 100% reliable its literally impossible. i have more miles on this thing with premix than oil injection at this point and have never had an oiling issue since. over or under oiling.

[kj4spj]

I replace the Reed valves now it's pulling gas but now it's starting to spit.I checked for vacuum leaks put my hand over the carburetor and dies out immediately.it will run fine for 15-20 minutes and then start just missing and losing power going to try to change out the coil or a CDI box

[chehystpewpur]

pull the exhaust off and run it for a bit. see if it runs longer with no pipe on it. that was the symptoms mine had after i got it running when i first bought it. it would be hard to start and once it ran it would have decent power and hit 35-40 mph but after about 3 miles would lose power fairly quickly then finally die. start back up after it cooled some and 10-15 mph back to the house tops. i initially burned the exhaust its an old 2 stroke trick that will atleast let you see if you need a new exhaust. if it runs better after trying to clean it and runs longer its time for a new pipe. aftermarket can be had for 100 bux or less and sometimes you can find a deal on a used pipe and get a really nice pipe and not feel guilty. i have a leo vince zx-r pipe that is an unrestricted one if you end up needing one. its old and its ugly but she still works and i will most likely never use it again.

[catchacuda]

Aug 3, 2019 21:31:40 GMT -5 chehystpewpur said:

pull the exhaust off and run it for a bit. see if it runs longer with no pipe on it. that was the symptoms mine had after i got it running when i first bought it. it would be hard to start and once it ran it would have decent power and hit 35-40 mph but after about 3 miles would lose power fairly quickly then finally die. start back up after it cooled some and 10-15 mph back to the house tops. i initially burned the exhaust its an old 2 stroke trick that will atleast let you see if you need a new exhaust. if it runs better after trying to clean it and runs longer its time for a new pipe. aftermarket can be had for 100 bux or less and sometimes you can find a deal on a used pipe and get a really nice pipe and not feel guilty. i have a leo vince zx-r pipe that is an unrestricted one if you end up needing one. its old and its ugly but she still works and i will most likely never use it again.

Went through this with a 1e40qmb atv. It drove me nuts. Burning out the pipe helped me some, it no longer stalled, just bogged. I eventually drilled some holes through the clogged silencer's internal baffles, problem solved.

That exhaust wasn't exactly the best, basically a 2' straight pipe and a 8" muffler/silencer on the end.

[mattyslimz]

If that plastic gear is not greased enough it WILL cause a failure, same goes with speedo pucks. I’ve only seen a speedo puck go out with 13k plus. My guess is if you haven’t added grease to your drive gear after 10k miles it should probably be re-packed with grease... I’d probably check it every 5k..

[kj4spj]

took the muffler off problem still going on.it spits and sputters at high RPMs not as bad but it's still doing it