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27 Posts
Discussion Starter · #1 ·
I'm replacing the Delorotta (spell check aye 馃ぃ) with the standard carb

The engine is a tuned engine as pictured below


I've just gave it a top end rebuild, new ngk plug (I'll get the number), indexed the plug to the exhaust port, rocket key.

No idea what all the port sizes are, more of a 4 stroke mechanic tbh

What jet sizes should I try?

Thanks in advance 馃憤

Super Moderator
3,092 Posts
There is no way to say which jet is going to be the best in your situation it all depends upon altitude, air density, temperature, fuel type and grade, 2-stroke oil type and mix ratio and of course the modifications of your engine...

Order yourself a jet kit start 2 Jets bigger than what's in there now with the needle raised all the way up then lower the needle down one click at a time and try it each time keep going and leaning it out until when you crack the throttle all the way open it wants to backfire and die that means you are too lean.. usually raising the needle up three clicks past two lean is about perfect ( well for me )

Razor mx500 (mildly modded)
108 Posts
I've found that those carbs tend to be jetted on the rich side from the factory (or they used to be anyway) so you might get lucky and just need to play with the needle valve adjustments. If it's not able to properly fuel your application then mr.kitty is spot on, pick up a jet kit and adjust accordingly... expect tuning to take a while.
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