Engine Trouble GT90 Conversion Kit Won't Start

Phabbits

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Aug 7, 2017
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One thing I noticed on the gt90 is that it has a windowed piston and trench port that are not needed for a case reed.You may want to try a reg (non windowed) piston also make sure that the piston crown doesn't come down below the intake at all.
That's very interesting, I thought that the window was necessary for the fuel to reach the top of the piston, after a little research I see that's not true. So I should make sure that piston crown never goes below the intake, it will need to use the slot in the cylinder then right, I forget exactly where that slot was.

with piston at top, check that rotor of mag has its key slot at about 1 o'clock and the flats in the rotor are about level with the ground
Now that's a great tip, when you refer to the rotor, that would be for the magneto right? So have the non-rounded sides level to the ground?

This is really helpful information guys, thank-you so much! I think I might create a document to help beginners like me on how to set up the GT90.
 


Tyler6357

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Sep 28, 2011
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1,112
As I understand it, the windowed piston are only required if the reed valve is connected to the cylinder intake but for a case reed valve like you've got it is not necessary. Ummmmmm, I think that's how it is. Also, I agree with Crassius, 1 o'clock for the rotor mag key at top dead center for the timing.
 
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Phabbits

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Aug 7, 2017
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23
Thanks for all the advice!

Hopefully I will be able to try all these things out next week, and get 'er going. :)
 

Phabbits

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Aug 7, 2017
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Just for closure on this thread, I finally had time to go back to this bike and try to get it working, two years later. I had to replace a rear flat innertube, and a broken plastic throttle, which should have no affect on the starting of the bike I believe, before attempting to start. I then tried to start the motor and it started! I ran it for about a minute with the choke on, and then I could turn the choke off. I have not had any issues starting it since.
 

Wrench

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Nov 14, 2018
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1,386
Just for closure on this thread, I finally had time to go back to this bike and try to get it working, two years later. I had to replace a rear flat innertube, and a broken plastic throttle, which should have no affect on the starting of the bike I believe, before attempting to start. I then tried to start the motor and it started! I ran it for about a minute with the choke on, and then I could turn the choke off. I have not had any issues starting it since.
Who ever thunk by fixing the throttle the bike would start :ROFLMAO:
 
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