lost power on my 49cc after reed valve install

[docjph83]

Hello there, I recently installed a reed valve on my 49cc two stroke engine, previously it had a boost bottle in it from BIS-Racing.com and it worked pretty well and then I read about on Reed Valves and all of its pros and cons and decided to buy one and install it on my engine.

And after running the engine with the reed valve installed it has half or even less power than it was when the boost bottle was installed. With the boost bottle its an easy 40kph, with the reed valve it barely goes up to 20kph. (BTW my bike is a motorized mini velo with 20inch wheels and im usng a 36 tooth rear sprocket). I read on some articles that you have to have a rich mixture for it but checking sparkplug its all black and sooty so meaning the mix is still rich. How do I solve this?

BTW I done some mods on the bike
1.) Dellorto clone Runtong carb with #70 jet
2.) custom exhaust

 

[butre]

the rich mix thing is bulls**t, it just needs to be rejected for it. usually it needs to be rejected richer, but without supporting mods you may need to lean it out.

if you didn't do any supporting mods for it that's a problem as well. without drilling a hole in the piston skirt it's just an intake restriction, like a restrictor plate in nascar, and without a boost port or third transfer port you're leaving a lot of power on the table.

there's also the possibility that you need to go much leaner as by installing the rees valve you solved a vacuum leak in the old setup.

once the spark plug is black it stays black. an old spark plug is not in any way a reliable way to measure jetting.

the reed valve doesn't add any power, and in many cases actually reduces it slightly. the main advantage is that it gives you a whole lot more leeway to modify intake port duration, and smooths out the power band making it much less peaky and giving you more usable power over a broader rev range.

 

[docjph83]

I'm also beginning to wonder of the reed valves do work on a 49cc engine. Do they? Or the reed valves good for 66 or 80cc engines?