airbox / pod filters / respro in general

[bighairymuppet]

hi has anyone modified their airbox or replaced it with pod filters?

Im assuming no pipes out into fairing required as air flow on bikes pretty good and air going into airbox should be cool enough?

I just can't leave things alone and want to improve my bike as much as possible within my very limited budget.

Do pod filters require you to alter anything or balance carbs? ( i dont think so but want to check).

Does it help the engine in any way not expecting increase in power just response?

diversion 600 1992

THANKS

[bighairymuppet]

no one appears to have tried any of this?

[m40man]

TBH, I suspect there's no good reason to do it, bar the inclination to experiment. Whilst you're fettling, you ain't riding .

[bighairymuppet]

true but its just to try and improve airflow and make it easier to service. Oh and the weather up here resembles a washing machine on spin.it'd be done in a day.

[Reaper]

Pod filters are used to increase air flow but also cause problems.

Now you need to ask yourself do you need the extra air flow have you or are you going to re-jet the carbs if not then Pods wont be of any use to you in fact they will upset the fueling.

The other thing with Pods is they don't really like the rain and tend to clog up in sivier weather and then upset the fueling again.

[General Gman]

Pod filters are a nightmare to set up, and will only work if you have fitted a jet kit (TBH, they will probably only work with a stage 3 kit).
And a race can.
Once you've got the jet kit in, then you either need to get it on a dyno to get the correct main jet (and to see if you need one or two holes in the slide) or spend long hours changing jets and road testing.
You would also probably find that although top end power is increased, low range torque suffers ......
They do sound cracking when you open the taps though.... my gixxer made a sound like a Harrier when you gave it some berries

[bighairymuppet]

thanks for the info. seems like pods are a bit too far. Any thoughts on any minor improvements

[General Gman]

Trouble with divvies is people generally leave the motor alone, so there's very little empirical evidence of what works.A stage one jet kit may well make it more responsive, and a K&N filter will also help a little, but there are not big gains to be had, methinks.
What sort of thing ar eyou looking to improve ? If you want a bit more pep low down, the you can lower the gearing - cheap and easy to do but it will affect fuel economy slightly.I had a 600N and it felt much zippier than the two 600s's I've ridden, prolly due to the lower gearing as standard.Make sure the carbs are well balanced - can make a big difference to the smoothness of the motor.

[bighairymuppet]

looking to improve response and hopefullly mpg , suppose lower gearing would feel good. might gte spare airbox and have a play come summer.

[CD]

The divvie is an 8 valve engine in a relatively low state of tune. If I were to be thinking about tuning one I'd look at what was done on the old 1970s/80s GS750s and Kawa 650s and go from there.

The earlier XJ600 made about 72bhp. www.totalmotorcycle.com/buyersguide/Yamaha-XJ600-YX600Radian-FJ600.htm
The Divvie looks much more sophisticated with its downdraught carbs and straight down inlets but only makes 60bhp. You might want to compare valve lifts, timing, etc to see if that's where the power went.

[5watt]

Can you check out the specs for a set of the old xj 600 carbs?
From the pictures on ebay they have larger internal diameter bores. This gives larger gas flow and therefore more power, at the expense of greater fuel usage. But 72b hp vs 60 bhp. Hmmm!
If they are similar they may fit the Diversion engine and its airbox which would be a great benefit.
After years of trying to improve the power of a Honda 90 engine in a monkey bike - big bore kit, tuned (fatter) exhaust, skimmed head and a bigger carb - the most most improvement came with the larger carb.

[5watt]

Check this thread too;
diversionclub.proboards74.com/index.cgi?action=display&board=600&thread=1194810043&page=1

[amorti]

The diversion has a side draft airbox, which I really can't imagine you could make fit. The side-draft carbs will be upset by being turned the other way up, I would think. Even if you could fit the inlet stubs for side draft carbs, and the xj600s carbs, there may not even be room for k+n's, never mind an airbox.

[CD]

As said in a different thread Dave Vizard in the 1970's was getting around 120bhp from Mini 1275 running a single 1/75" SU carb. I dont know how much air the SU flows but I'm sure its a not twice as much as the set used on a Divvie 600. In other words if a single 1/75" SU is enough for 120bhp I'm sure the Divvie carbs are capable of a lot more than 60bhp.

I personally think the Divvie performance is reduced by smaller valves and lower valve lift, but have no data to back up my idea.

BTW