ram air.
-
Ram Air can be tricky.
the rs250 mentioned is NOT the aprilia rs250.
It's unfortunately not just a case of ram it in there and Bob's your Uncle.
Several things to consider for the DIY Ram Air maker.
Firstly, there must be equal pressure between the airbox, carb float bowls and tank. This means that the carbs should sit inside the box, and the box should be linked to the tank.
However, when decelerating on a closed throttle, the tank should be cut off from the airbox otherwise the tank pressure could be higher than the airbox pressure as you slow down which would force fuel into the engine, richening things up to a point where it'll stutter as you try to accelerate again. This can be controlled by a solenoid inline between the airbox and tank to shut off the airbox/tank pressure hose during braking, activated by the brake light switch. The RS250 uses this method, but the solenoid is mighty
expensive. An air solenoid from the MC18 should work quite nicely here (I have some of course :-) ).
I found that the airbox had very little difference from open carbs down low (slow speeds, low throttle opening) and carb settings were usually within the same range as previous, un-rammed settings, but the mains were consistently a couple of sizes larger.
I also needed to adjust the float height 0.5mm higher to counter detonation, and on long, fast circuits would lower the compression ratio (increase cc ~0.5cc).
Carbs were fitted with HRC Avgas kit (including air correctors).
There's no doubt that the ram air works, but it's only really noticeable above 100mph.
Testing on Bira Circuit in Pattaya back to back showed a consistent increase from 130mph to 133mph, without and with the ram air. The system tested was the Harc-Pro type.
The best plan is to make the box as large as possible, and then pack it inside (reduce airbox volume) for shorter, slower circuits or it may not have any effect.
Really only good for race use, unless you want major street cred points!
Matt -
-
hi henry i remeber seeing ur mail on a digital speedometer on a jap website on topica, do u still have the link? that digital speedo damn chio wor...
-
dun have leh....
i oso looking for 1 now...
i go alot of chia bang find liao, they only got turbo timer, vacuum gauge etc etc, no digital speedo.... looks like really must order from japan liaoz. -
-------------------------------------------------------Originally posted by paikuakia^^:
paikuakia recently saw a aprilia wif carburettor wif 2 carby on the right hand side so chio sial .no air box 1 leh the frame fugging chrome sial oso aprilia 250 leh -
btw u got ur jha chmbers?Originally posted by nismoS132:dun have leh....
i oso looking for 1 now...
i go alot of chia bang find liao, they only got turbo timer, vacuum gauge etc etc, no digital speedo.... looks like really must order from japan liaoz. -
-
nxt time we come out u will knowOriginally posted by Laksa:btw u got ur jha chmbers? -
------------------------------------Originally posted by paikuakia^^:
i personally prefer the JOLLY MOTO more
paikuakia wanna go follo me go amk find pgm4
i wanna sell my bike liao -
Originally posted by NEW^_^BIRD:------------------------------------
i personally prefer the JOLLY MOTO more
paikuakia wanna go follo me go amk find pgm4
i wanna sell my bike liao y pull my nick in
quick sell lah -
