50cc Gy6 won't go above 10mph By grizzly (Read 1,553 times)

[grizzly]

Yep, it fired right up. 

I think the new carb must be the problem, since it was starting beforehand just fine, it was a performance problem. 

I was checking the fuel line to be working, and sucking on the vaccuum got a steady stream of gas to come out of the line when it was off the carb, but putting the vaccuum line back on the manifold and trying to start it didn't pull any gas out into my waiting can. I also couldn't get it to start by sucking the vacuum hose manually while trying to start. 

[jct842]

You have a vacuum leak. Make sure all of the hose outlets on the manifold are either used or have a cap on them. carb/manifold connections could be loose. One way to find a leak on a running engine is to spray some carb cleaner, ether, wd40 or even mist with a water spray around the connections on the carb and the rubber manifoldmanifold. If there is a leak the engine speed will change. the rubber manifold can crack too, if it does replace it. They can be sealed but usually do not last long.

[grizzly]

I'll check it all thoroughly, the intake manifold is new as well, I ordered it before the carb and put them both on at the same time. 

[cyborg]

You have to physically inspect all vac lines and the intake manifold,,,it may have an obstruction,,,also what I do on my machines is go clear vac and fuel lines so a quick peep lets me know what's going on

[grizzly]

Ok, I'm not sure what exactly it was, but I retightened the intake manifold, and hooked the vacuum line on with a stronger clamp, and it puttered to life. After revving it for a minute or so, I slapped the seat on it and drove it down the street. It powered up to 20mph and kept the needle there steady as a rock. It sounded deeper and slower than I'm used to, so I think at this point I need to fine tune the new carb.

Thanks for the help everyone, I'll be back if tuning doesn't fix the issue.

[newbie]

Wowsers- Alley spotted that intake manifold problem quick ! Just wanted to hijack this thread and thank Alley, Bashan, and cyborg for all the good info and help they give to all on this forum . From their ( and others ) suggestions I see on your forums I just adjusted the valves on meh Icebear 150 ( about 700 miles on odo ) and all i can say is- WOW . . wow - what a difference ! The intake was at .0015 and the exhaust was at -0- !- now .004 and .005 . Thanks for all the time and consideration for us newbs that you guys and gals put into the site ! Alleyoop cyborg grizzly,Alleyoop,trashtruck12172,cyborg BTW- looking a a taller aluminum intake manifold to get rid of the rubber one - any 1 have suggestions ?

[cyborg]

Talk to Dan at martins mopeds he'll set you up

[newbie]

thanks- i'll check it