SV650 Velocity stacks

Hi all, just found these on the factory pro website.

http://www.factorypro.com/Prod_Pages...Dyno_Developed

DShould be very easy to fit, the dyno graphs look good, any thoughts?

Tapemonkey

Originally Posted by tapemonkey

Hi all, just found these on the factory pro website.

http://www.factorypro.com/Prod_Pages...Dyno_Developed

DShould be very easy to fit, the dyno graphs look good, any thoughts?

Tapemonkey

If you like 'bling' then you can't even see them!!

Do you need the claimed +5% hp at 9k, +~2.5% in other bits? If so cool, if not then what a waste of good money that could be spent on petrol and tyres enjoying yourself!!

I don't think those are percent gains, I think they're HP gains.

If the figures are correct for the 35/70mm combo then the increase at 6000rpm is almost 9%. Sounds pretty good to me and perfect for a road bike.

Tapemonkey.

Originally Posted by tapemonkey

I don't think those are percent gains, I think they're HP gains.

If the figures are correct for the 35/70mm combo then the increase at 6000rpm is almost 9%. Sounds pretty good to me and perfect for a road bike.

Tapemonkey.

I know ... I converted them to approximate percentages to give you an idea of gains as % as it might be a bit more meaningful, at least a different view ...

Oh and 40 to 41.5 is 4% ... EDIT: my bad ... you are looking at the second chart, not the first!!

Basically they have one for more midrange, one for more top end. I'd say for the road the midrange one is prolly more use??? ... but personally I would struggle to justify the expense when I could just use ~500 more RPM and get the same power!!

Shame the graph looks too handmade to me, I doubt very much there's much difference, having played with different length trumpets on the flatslides for no big changes.

[21QUEST]

Originally Posted by Robw#70

Shame the graph looks too handmade to me, I doubt very much there's much difference, having played with different length trumpets on the flatslides for no big changes.

Off topic I know but Rob, would a standard SRAD front wheel work with 'K' series yokes and radial caliper forks?

I know it'll need to be centred but not sure if the slightly wider hub of an SRAD wheel will be too wide meaning the discs touch the inside surface of the calipers. Thanks.

Ben

Yep thats what im running (well TL anyway) The hub is 7mm too wide so 3.5mm off the captive spacer/nut gets it all central, or you can just do the pinch bolts up with it in the right place or have a spacer made to sit outside the leg.
The discs are 2mm closer together so you have to be careful with new pads as the inner pistons are nearly bottomed out.

[21QUEST]

Originally Posted by Robw#70

Yep thats what im running (well TL anyway) The hub is 7mm too wide so 3.5mm off the captive spacer/nut gets it all central, or you can just do the pinch bolts up with it in the right place or have a spacer made to sit outside the leg.
The discs are 2mm closer together so you have to be careful with new pads as the inner pistons are nearly bottomed out.

Thanks Rob


Ben

Originally Posted by tapemonkey

I don't think those are percent gains, I think they're HP gains.

If the figures are correct for the 35/70mm combo then the increase at 6000rpm is almost 9%. Sounds pretty good to me and perfect for a road bike.

Tapemonkey.

Hi TM -

Correct - The hp numbers are are definitely "HP" gains - not percentages.
All the Factory Pro dyno tests are full, steady state tests and the hp scale is True HP scale (that's why the HP numbers are lower than djhp)

Hi Robw#70 -
The sv650 dyno charts were tested every 1000 rpm, as is common for loaded, steady state testing - that is probably why, if you are used to looking at a simple sweep tests (ala dynojet and dj clones) would see it as "odd" looking - but really - it's a better way to test - even when tuning FI, the bike's only at full throttle for less than 10 seconds at a time
And instead of only 1 sample at many rpm points (dj style), each rpm point has 100's of averaged torque and hp samples at each point for better accuracy.
You could actually do steady state testing every 100, 250 or 500 rpm, but it would cause more "engine run timer".

Another thing about stacks - They will always change power output when you change lengths. Better or worse, in one rpm band or another - And - the shape of the flare and inner diameter of the stack are equally important.

I've always seen carbs react to length changes - BUT - stack changes DO affect the way a carb delivers fuel and jet size required for Best Power.
Quite often the power changes that the diff. stacks cause are masked by the changes in the carb jet requirements -
That's another reason to use steady state testing and a 4 gas EGA, rather than a simple o2 sensor in a sweep test to help tuning -

Also - keep in mind (for the tinkerers) that what stack configuration works best on a stock engine may not be the correct stack configuration for a ported or cammed or big-bored engine -

Marc Salvisberg
415 491 5920
www.factorypro.com
marc@factorypro.com

I'll post my thoughts on these soon, my stacks should arrive on Monday.

I went for the more midrange option of 35/70mm stacks, should be interesting.

Tapemonkey