Monster moto 80cc wont run for long

#1
Hey all, I don’t know if this forum is still active but I have a monster moto 80cc minibike and it has been in storage in the garage over the winter and now, after I drained and replaced the gas and oil it only starts for a couple seconds then the engine stops. When I turn the throttle within the first few seconds of it starting I can get it to move but then it dies out again. When I don’t use the throttle it dies out after ten seconds max. Any and all help is really appreciated cause we want to get the bike back up and running.
 

Attachments

Addicted 2 Minis

Well-Known Member
#6
Also, these are notorious for having fuel problems, someone posted a little while ago that the manual recommends running with the choke partially on, i looked for it again in the manual but didn't see it.
 

Addicted 2 Minis

Well-Known Member
#9
There's a bolt on the bottom of the carburetor, it takes a 10mm wrench if I remember correctly. Remove the bolt being careful not to lose the fiber washer if it has one ( usually red in color ). Take some carburetor/choke cleaner and spray in all the holes within the float bowl, you may have to remove the float. Wear some safety glasses and gloves to avoid getting any carb cleaner in your eyes while spraying in the holes. There's probably a video on YouTube that would better visually explain how to do this. Just be careful as there are some small parts that could easily get lost, i recommend getting a small rag or towel and lay the parts out in the order as you remove them for easier re-assembly.
 
#11
I had a similar problem with my Benelli Dynamo. It would start, run 10-15 seconds and die. Wouldn't start again until several hours to a day later when it would do the same thing. I figured it was either a carburation or a timing issue Cleaned the carb with my ultrasonic cleaner and ran a copper wire through the jets and passages on the carb, even tried a different carb--no change.

Then I looked at the timing. Point gap was correct. Plug gap was correct. Double checked the timing it was correct and provided a nice spark. Still wouldn't run for more that 15 seconds. The only other thing I could think of was the condenser in the magneto. But since it was inside the magneto and difficult to change I was going to switch over to an external condenser at the coil. But before I did that I decided to try a different spark plug even though the one that was in the mini gave a nice fat spark. The new plug worked--the bike started and continue to run.

I don't know why the original plug gave a good spark when tested but stopped working after a short period of time but still provided a spark when tested.
 

Doc1976

Active Member
#12
I didnt read anything about if the choke is affecting running? I assume you are choking it when you are starting it? If so will it stay running with the choke on? If it does, then you need have a clogged or partially clogged main jet. If it stills dies after running for a bit, then I would suspect the needle jet that controls fuel inlet to the carb may be stuck. I had an old dirt bike once acting the same, and the needle valve had shit in there and it would fully close, but only barely open. So it would take and hour or two to fill the bowl. Are you leaking any fuel? Any way I'm sure you will need to clean the carb.
 
#13
There are some real crappy spark plugs coming from over seas and some of them even have popular brand names on them. I had a lot of trouble with brand new 8hp B&S engines going dead with only 2 hours of run time on them. It was bad champion plugs, switched over to Autolite plugs and the engines ran great. Problem solved.
 
#14
There's a bolt on the bottom of the carburetor, it takes a 10mm wrench if I remember correctly. Remove the bolt being careful not to lose the fiber washer if it has one ( usually red in color ). Take some carburetor/choke cleaner and spray in all the holes within the float bowl, you may have to remove the float. Wear some safety glasses and gloves to avoid getting any carb cleaner in your eyes while spraying in the holes. There's probably a video on YouTube that would better visually explain how to do this. Just be careful as there are some small parts that could easily get lost, i recommend getting a small rag or towel and lay the parts out in the order as you remove them for easier re-assembly.
Hi! I am having a problem with my Monster. When I try to start it, it doesn’t start up, but when I hold the throttle while pulling it, it cranks up and I can jump on and ride, but once I let the throttle go,it cuts off. I cleaned the carb out and filter
 
Top