Tunable leak jet circuit maximizes volume of fuel and duration of fuel spray for any condition. Investment cast and finished to precise tolerances. High volume vertical check valve located in the QS3 for precise, consistent fuel metering. Stops hesitation and bogging. Instant throttle response. Improved low end performance. Fits all Keihin FCR carbs. Simple bolt-on.
"I added an FMF pipe and had a horrible flat spot on the Lowe end. I added the Boyesen QS3 and all was well with the world. The bike pulls cleanly from idle to flat out. It also starts well. I could not be happier. I can not give a high rating on durability as I just got it. But knowing Boyesens rep I can give it a guess as top quality as with all their products I have used on my 2 smoker RMB in the 70's."