GY6 150 1P57QMJ No start pops though exhaust kicks back By bigkahuna427 (Read 6,128 times)

[bigkahuna427]

Just an update here. I put a 26mm ($22 shipped to my door) carb on it and saw a nice improvement in performance.

Regarding the pre-ignition on start up. I have 3 CDI modules here and all do the same thing in that the timing does not move from idle to to high speed. I did see a video at 49ccscoot that compared stock and "racing" CDI modules that showed timing on a 50cc scooter. He had a stock module that started off low and advanced to about 25 degrees BTDC with the racing modules fully advanced to about 25 degrees. Mine is at about 35 degrees advanced all the time. 2 of the 3 modules I have here are stock but both are fully advanced at idle.

I was able to find a picture online that showed both TDC and the position of the raised metal that triggers the CDI. With the flywheel at TDC my raised metal piece is midway under the forward most bolt that secures the impulse coil. On the photo I found that raised piece is forward of that same bolt. If I am thinking about this correctly I believe this puts the timing further advanced and certainly what I am looking for. Not sure if there is variation on the location of that piece but hoping the new flywheel I have coming will have a different location that will retard the ignition.

Variation in this location?
Poor manufacturing?

[cyborg]

It very well may be a manufacturing error,,,or the maker put the wrong one on by mistake

[bigkahuna427]

Here is another update:

Flywheel arrived last night. I installed it right off. Comparing the two flywheels the new one was lighter and slightly smaller in diameter. The raised lug on the flywheel was a bit thicker but still when installed the air gap on the CDI trigger was quite a bit larger and more than a credit card. The engine runs so I am not going to worry about that. You can see in photos the difference in the placement of the lug. I was concerned in looking at this it wasn't going to be enough as it looks to me to be maybe 5 or 6 degrees. It was enough of a change and the engine now cranks and kicks just fine.

I have fixed a couple of other things like charging system quit which ended up being a faulty connector latch causing the connector to slide apart just enough to cause an open circuit at the regulator/rectifier.

The last remaining item is a surge at higher speeds. This is not a full misfire but I would describe it as a lean surge. If I had access I would put it on an exhaust gas analyzer but going to have to do this by the seat of my pants. I have a set of jets coming probably go up a couple of numbers and see what kind of results I get.

[cyborg]

Bingo,,, the maker put the wrong one on

[bigkahuna427]

It did not seem like there were different versions. When I ordered it they just asked me how many poles on the stator and that is it. Any regards the difference was night and day.

I did re-jet the new carb. The old jet was marked 0.74 which did not seem to make any sense by everything I found online. I just put a 120 jet in it which certainly cured the problem and the spark plug looked correct after a good ride at 50 MPH.

Thank you for the help I think I am all set with this one.

[cyborg]

Nice!!! Glad you got it sorted out