A reputable company like Boyesen would not deal in gimmicks if they did not work.
The "wing" stabilizes the air approaching the slide in the bottom half of the throttle bore. Without the divider, at less than 1/2 throttle the air piles up against the entire slide, producing turbulence and therefore a reduced vacuum signal at the main jet orifice (needle jet). This results in poorer atomization and a need for a larger main to compensates for this lack of vacuum. The divider improves throttle response and slightly improves torque at less than 1/2 throttle. The difference is more noticeable with larger engines.
Here's the thing, that bore implement does not work for squat in the real world. If you want one my neighbor will sell you a keihen pwk 24mm with it grafted to it for 200$ it was a waste of money and a pain to even try to tune. Say what you will about them not wasting their money on research etc etc, I can tell you from first hand experience dealing with on its horrible. And I know how to tune a carb very well.
Re: the Boyensen "wing" products. I read several reviews. Some people swear they work well while others swear they don't work at all... so I would call the results inconclusive.
If you buy the product and try it you can be the judge until then I wouldn't believe what you read I a review. It's 100% bs. Same as those tornado or what ever kind of junk they sell now that's suppose to create a turbine in your intake. Buyer beware on these ridiculous waste of money. But from 100% first person experience the divider is 100% worthless, not from some phony review made by someone trying to sell a product.
For scooters, which are typically either at idle or WOT, this wouldn't make a bit of difference. Any supposed impact would be at part throttle 1/4-1/2. How often do you ride in that range?
I don't think this is Boyesen. I think it's someone that's modified a Boyesen.
Design tries to increase velocity prior to the air entering the slide. The slide typically does all this work. But now you have a flat plate stuck in the airflow, which would create new turbulence. Overall impact would be to lower airflow during WOT.
The only way to have a small and large carb is to have 2 bores (or 4, in the case of Quadrajets.)
The carb was actually used on a Kaw KX65 with an Athena racing 82cc kit. We ended up using a 28mm with a power jet rather than using the modified 24mm. I built 2 of the exact same engines/bikes and ran the 28mm on one and the modified stocker and the ended up going back to the stock carb from the other one.The modified just didnt want to pull almost like it was obstructed. Put the wideband on it and it wasnt able to ever stabilize at any throttle while moving, did ok at an idle and no load. It felt like it was too fat all the time even tho the AFR was always on the lean side, never felt right after 20 jet and needle changes and wasnt going to keep trying to blow up a 600$ cylinder. It was fun.
Ive ran both the bikes VS yz/kx/and cr 80/85s and they destroy them, Its not even a fair race. I currently have a 01 yz85 Im planning on stroking and boring after I blow it up, if I can that is. I should say these bikes arent for me, theyre my 9 year old twin nephews, but I ride them more than they do.
OK, so what I thought. The flat plate does nothing more than add turbulence / reduce airflow.
Not surprised you couldn't tune it. At just above and below 1/2 throttle, air flow would be all screwed up as air fights between the plate and the slide.
In general, less things in a carb throat are better, hence why flatslides make more power than CV carbs. Seems silly to put something in the middle of a flatslide.
84 Aero125 Goldie, For Sale, parts bikes too
09 Stella For Sale
86 Razz
87 YSR50
56 LD150
79 P200
