Lurching in higher RPM range

Clats97

New Member
Jul 21, 2019
25
9
3
24
I have a new build. It's a gt5 engine stock. For some reason when I approach 25-30kmh, it starts lurching and stumbling.

Thing is, it feels more physical than anything.

Any ideas? The jetting should be fine as I have the same jet I usually use
 

javy mcdees

Active Member
Jul 30, 2018
143
59
28
50
I got a great running gt-5 been using last 4 months daily and went out this morning to go to a job she fired up then quit. found no spark a magneto not within range ohm reading and changed it. got spark now still no fire. pulled carb checked all the jets for clog all good just wont fire for me. from running perfect to FU today how nice! What carb you have and are you sea level?
 

Clats97

New Member
Jul 21, 2019
25
9
3
24
I got a great running gt-5 been using last 4 months daily and went out this morning to go to a job she fired up then quit. found no spark a magneto not within range ohm reading and changed it. got spark now still no fire. pulled carb checked all the jets for clog all good just wont fire for me. from running perfect to FU today how nice! What carb you have and are you sea level?
600bft above, did you check your wiring? Change spark plug? Choke working properly? Proper compression? Flow of gasoline not impeded?
 

Jimmy Bloodmaker

Active Member
Nov 24, 2018
176
60
28
midwest
your probably running way to rich. if nothing has changed since you moved it over, then your float is stuck, you have a bad needle valve in the carb, or you need a smaller jet. or you muffler is clogged, port, gasket in the way of a transfer, something lodged in your intake, piece of debris in you jet. bout all i can think of at the momment, but spudder is rich, dragging back like someone killed the gas an when it gets to a certian point it races back up, thats lean. if it slows down when it gets hot, you are lean. i can run flat out till i run out of gas on most of my bikes. long as air is moving, their are happy to push.
 

Clats97

New Member
Jul 21, 2019
25
9
3
24
your probably running way to rich. if nothing has changed since you moved it over, then your float is stuck, you have a bad needle valve in the carb, or you need a smaller jet. or you muffler is clogged, port, gasket in the way of a transfer, something lodged in your intake, piece of debris in you jet. bout all i can think of at the momment, but spudder is rich, dragging back like someone killed the gas an when it gets to a certian point it races back up, thats lean. if it slows down when it gets hot, you are lean. i can run flat out till i run out of gas on most of my bikes. long as air is moving, their are happy to push.
Why woukd rich cause lurching? I went to a 77 and it was 4 stroking like **** and didn't even move. I've tried every size jet