Having run and dyno tested an open air box on a carbed 900 Monster, I settled on a good set up with shortened velocity stacks which thickened the power and torque curves rather than gave any major top end power at the expense of mid range and bottom end. Tuning theory leaned towards the latter happening but it didn't. The inlet manifold are a mile long anyway..
The conlusion I reached because of this was that the velocity stacks were too close to the filter element making an inefficient air box even more so. Shortening the velocity stacks improved the available volume in the air box. The shorter stacks mitigated a shallow air box design to some extent. The location of the filter, available space between the filter and the stacks and the location of the carbs on the air box are all part of the equation. I'm no expert on this for sure but look at a modern air box on a GSXR and see the difference.
What about trying pods? The K&N RU 1750s have been shown to flow enough air to make over 100hp in worked carburetor desmodues. They also drop 1.5 kilos in weight and make servicing easier. I have a friends bike which runs very well with them, a 944 Superlight with FCR39s, a little porting, dialed cams, Dyna coils, Igniteck Ignition and Ti valves. This bike does 3rd gear wheelies down hill. It only required a change in needle position when changed from an open air box (#5 to #6). I did this mod on the bike as I owned it before by buddy. I painstakingly tuned this bike over six months.
I got my kids and Math teacher wife to help me calculate the filter area of the pair of pods compared to the K&N flat filter. The pair of pods had about 30% more filter area (roughly), I can't remember exactly. There was significantly more. Their shape concerned me and whether there is a good radius inside to give a velocity stack effect. If Jako and MBP have used them to good effect then I shouldn't worry too much. (Anyway Chris Kelley don't sell crap).
When I am well I will conduct road testing and then whack the old girl on the dyno. If I get 81-82 hp and no losses in the midrange or bottom end then I will keep them.
By the way she has JE high comps, advanced stock cams on Vee Two pulleys, Termis and some porting on the inlet side. There is also Kelley coils, Igniteck module, Vee Two/Barnett clutch (-1.9 kilos) and 1 kilo lightened stock flywheel. Going nuts with being ill with the flu at home, I got out of bed and carefully weighed all the stock components removed or replaced with lighter stuff and have dropped a whopping 16 kilos from the empty tank weight as weighed by Sportsrider in 1995-1996. From 186 to 170 all fluids sans gas. Pity I can't afford light wheels. As an aside, the sprung weight is low but the unsprung weight is heavy with the stock Brembo wheels, and I feel it in the handling as the unsprung weight is a bully to the chassis. The sprung and unsprung weight are out of balance to me.
With Pods servicing is easier and with a Shorai battery I have fitted the coils and ignition all into the battery box which I have seperated from the air box. Removing the ignition bracket removed another 200grams. That's 3 kilos off with the Shorai, 1.5 kilos off with the pods and 200 grams off with the ignition bracket.
I'm concerned about crankcase breathing which I will have to deal with (see the other thread)!
I'll get well and report soon.
Cheers.
For medicinal purposes.
