Installed reed valve and windowed my own piston yet the bike won't run.

Anthony Barbosa

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Nov 9, 2023
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So I recently got a reed valve from amazon, link here just in case you might need it. I windowed my own piston a pretty decent amount (following the "outline" already in the piston from behind the walls) and I did all this in one single day. Now, when I go to start it, it doesn't want to stay on. All I hear is a few pops here or there when trying to start it but the engine doesn't actually start to idle. Then, when I try and rev it up cold (ik not a good idea but just cus I had to test) it does rev up there but it like hesitates. It revs, stays there in that rpm somehow and eventually doesn't even idle, just dies on me. I don't know what it could be. In case this is relevant, I do see mist coming out from the intake port. Maybe the gasket in the kit doesn't exactly seal it? Maybe a reed valve defect? I'd like some insight on the matter please
 
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Always take pictures of your progress no matter what. and if there is issues we have something to look back on. This saves you from disassembling and showing what you did.

Where is the clip at on your metering needle? Move it down a notch or two.
 
Always take pictures of your progress no matter what. and if there is issues we have something to look back on. This saves you from disassembling and showing what you did.

Where is the clip at on your metering needle? Move it down a notch or two.
I'm currently using an HP carb and not the stock one. Current jet is a 72 but when I change jets its very unpredictable. I'm not able to tell whether I lean it or rich it out, if there's been a difference. Using the previous setup of just intake and carb and no window, I was able to tell whether I was gaining or losing performance. This current setup has me baffled.
 
I'm currently using an HP carb and not the stock one. Current jet is a 72 but when I change jets its very unpredictable. I'm not able to tell whether I lean it or rich it out, if there's been a difference. Using the previous setup of just intake and carb and no window, I was able to tell whether I was gaining or losing performance. This current setup has me baffled.
Yea, those carbs aren't very good, they leak air from every orifice. PZ19, VM18, or the old reliable NT/Bofeng is better.
 
I'm currently using an HP carb and not the stock one. Current jet is a 72 but when I change jets its very unpredictable. I'm not able to tell whether I lean it or rich it out, if there's been a difference. Using the previous setup of just intake and carb and no window, I was able to tell whether I was gaining or losing performance. This current setup has me baffled.
I never knew what HP stood for, I guess it's "Help Please".
 
I may have a lead. It seems as if when I rev the engine there's gas coming out of the intake port. I tested this to be extra sure by drying the area around it with a tissue and trying to start it again. It sounded like it was being choked and didn't want to rev up. But when it did, there was in fact gas droplets coming out where the reed area meets the intake port. What could I do to seal it?
 
Take it apart
Clean the surfaces well with something like acetone or lacquer thinner
Use Motoseal

If the the surfaces are rough it’ll help to block sand both surfaces to get smooth, clean, flat mating surfaces before cleaning and sealing.

I use #400 grit on both intake and exhaust ports
 
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