motor runs for a block then wont accelerate

[AussieSteve]

Like 6 meters hehe, Im a newbie, giveme a break lol

Sorry gemballa, just having a bit of fun and don't worry, we've all made our share of silly mistakes.
Just the same, I'm surprised that you got it started.
... Steve

 

[motorpsycho]

i don't see how the motor even ran with the carb on upside down. there is no possibly way for it to run, plus the throttle cable would have been coming out on the bottom, kinked & more than likely not functional. the fuel line would have been on the opposite side, so he would have had a mile long fuel line (more than likely with kinks) from the tank to the carb. PLUS, when he opened the fuel tank petcock the carb would have just leaked fuel out all over the place, and there is no way that the float bowl would have ever filled up. if the float bowl did fill up with fuel, all of the fuel would have just drained out of the main jet by gravity. the fuel woudl have either flooded the cylinder, or just ran out the back of the carb. I don't see how the float bowl would have ever gotten fuel, or how the engine would ever run.
maybe he just put the air filter on upside down?

 

[Al.Fisherman]

i don't see how the motor even ran with the carb on upside down. there is no possibly way for it to run, plus the throttle cable would have been coming out on the bottom, kinked & more than likely not functional. the fuel line would have been on the opposite side, so he would have had a mile long fuel line (more than likely with kinks) from the tank to the carb. PLUS, when he opened the fuel tank petcock the carb would have just leaked fuel out all over the place, and there is no way that the float bowl would have ever filled up. if the float bowl did fill up with fuel, all of the fuel would have just drained out of the main jet by gravity. the fuel woudl have either flooded the cylinder, or just ran out the back of the carb. I don't see how the float bowl would have ever gotten fuel, or how the engine would ever run.
maybe he just put the air filter on upside down?

My first thought was, how in the world can one put a carburetor on upside down, then my immediate thoughts were the same as yours. The only thing I can think of is that the fuel wasn't on till he tried to start it then maybe, MAYBE, enough fuel got into the cylinder and fired. Strange things can and do happen.

 

[Al.Fisherman]

I recently installed my first 80cc chinese kit on a mountain bike, I had the same problem, the engine started, then after few meters would stop....

Then I realized that I installed the carburator on the wrong side (up-side)

THe black plastic tubes for air intake should be downside, than worked wonders

SO maybe your problem is the carburator, or something related with air-intake

Are you telling us that you actually mounted the carburetor on the cylinder such as in one of the two pictures below?

 

[motorpsycho]

the carb could techically be mounted to the intake anyway you want to mount it because there is no keyway, flat or notch in the intake tube to orient the carb. the correct way.
sure, it could be mounted upside down, but i highly doubt that the engine would run.
BUT, maybe... in a million to 1 chance that the conditions were right and it actually ran would be amazing.

 

[Mike Hunt]

my guess is that op probably meant that it was sideways rather than upside down. depending on which side was up its quite possible that it might have fired a couple times.

 

[AussieSteve]

When I think about the possibilities, Al's pics or Mike Hunt's suggestion, they would all allow some fuel/air to be sucked into the intake, but all would have fuel p i s s i n g out of the carb. I wouldn't be trying to start it, but it is possible that it would run for a couple of seconds.
Anyone care to try?
(Not me)

... Steve

 

[j2thevvizo]

ok it rained for a day or two so i just got trying make my bike work. first thanks for all you replys. all your ideas about the not getting enough fuel to the combustion chamber were correct but not for the reason i thought was going to be. when i went to check my fuel filter and fuel line for some reason on loosed my gas cap and i notice the gas in the tube start rushing down into the carb after i has taken the cap off. i tried the riding the bike with cap on but loosened and it worked fine. i tried tightening the cap and the bike stalled out. it turns out that my gas cap creates a seal that prevents the gas from flowing through the filter. so now i have a new problem. i have to ride with gas cap loosened ad risk splashing fuel all over me. has anyone else had this problem. is the something i dont now.

 

[AussieSteve]

ok it rained for a day or two so i just got trying make my bike work. first thanks for all you replys. all your ideas about the not getting enough fuel to the combustion chamber were correct but not for the reason i thought was going to be. when i went to check my fuel filter and fuel line for some reason on loosed my gas cap and i notice the gas in the tube start rushing down into the carb after i has taken the cap off. i tried the riding the bike with cap on but loosened and it worked fine. i tried tightening the cap and the bike stalled out. it turns out that my gas cap creates a seal that prevents the gas from flowing through the filter. so now i have a new problem. i have to ride with gas cap loosened ad risk splashing fuel all over me. has anyone else had this problem. is the something i dont now.

Wow. You know, after I posted my suggestions the other day, 'vapour lock' crossed my mind, but I discounted it because virtually all of these caps leak.
It does raise an important issue.
I wonder how many others are experiencing this to a degree? Even though most caps weep a little, it's not necessarily enough to compensate for the potential vacuum if the cap can't breath.
About all that I can suggest is a tiny, (~0.5mm - 1mm), hole in the cap. Or try another cap. I've got two and one seals really well, so I might have the same problem. (That cap is on my 3L tank, not fitted yet.)
On many dirt bikes, a thin hose runs from the cap to the handlebars to allow the tank to breath without weeping through the breather hole.

... Steve

 

[gemballa]

Are you telling us that you actually mounted the carburetor on the cylinder such as in one of the two pictures below?

Yeah! Like the right picture, the motor was brand new, so it had clean air on the system I guess, and ran for about 2 seconds

Its true, belive me if you can!