Velocity Stack for 81 xs 400 stock carbs ?

[riotten22]

Is anyone running velocity stacks on there xs400? I am looking for a place to buy and would like to know what inside diameter you went with? If you would care to share your jetting setup too that would be awesome.

Thanks,

 

[Sandrew]

54mm for sohc carbs.

 

[riotten22]

Ok I have 54mm pod filters but anyone know where to get a 54mm velocity stack?

 

[riotten22]

So here is just about the one and only site I could find for velocity stacks on the BS34s they are $65 a pair or $35 each and they are made per order. They look very good.

http://www.steeldragonperformance.com/products_2.html

 

[xs400cafe]

www.dimecitycylces.com has them. I go there for almost everything, they even have the jets you would need to rejet the bike.

 

[NightHawk666]

I have never ran them before, any advice or rejetting sizes? Also heard of cutting the spring shorter inside my carbs to get a quicker throttle snap.?.? Any ideas? thanks

 

[Yamaguy55]

Running without air filters will not prolong engine life. Nor will it make it run better. Ideally, smoothing the air coming into the carbs will give you the best throttle response. Velocity stacks will not do that. For the really inclined, providing cold air to the carbs from in front of the engine would be the best yet, as it is denser and would provide better O2 content.

Leave the slide spring alone. It allows the slide diaphragm to respond to the engine demands properly. Increasing compression and fitting a higher lift cam may give you the "snap" you're looking for, but messing with the spring calibration will not.

If you go this route, plan on at least making the mains richer. You'll have to figure that out as you go. each application would be different.

 

[Hishman]

From what i've read they are useless. They don't really help with tuning and the performance gain is next to nothing especially on a stockish 400 (assuming you havn't re-phased etc) Now i will say they look pretty cool and you can equip them with sponge filters that actually do something unlike the screens that only keep out leaves and things of that sort. So if your willing to spend 60$ or so to make your bike look cool then do it! But if you think they will improve performance then id skip them.

 

[Yamaguy55]

From what i've read they are useless. They don't really help with tuning and the performance gain is next to nothing especially on a stockish 400 (assuming you havn't re-phased etc) Now i will say they look pretty cool and you can equip them with sponge filters that actually do something unlike the screens that only keep out leaves and things of that sort. So if your willing to spend 60$ or so to make your bike look cool then do it! But if you think they will improve performance then id skip them.

You don't find them on any true performance bikes. Any filter that will not be obvious will either clog right away or be so coarse that why bother. They are essentially a throwback to the fifties and early sixties. As engineering learned more, they found that smoothing the airflow by eliminating turbulence gave great gains, as did cold air induction; as cold air, due to density, holds more oxygen per gallon of air. Look at the emission compliant power output of modern sportbikes, and use their tricks that apply, unless looks are more important.

Image is fine, but I'll take performance and reliability anyday.