Pulling secondaries.

One minute i'm thinking Yes and then No ,i need help.SO

POLL ABOVE

Only you can answer that Gus.
Personally I reckon the B1250 would be quicker with steering and suspension mods. If I was happy with the fuelling I'd be leaving it. I know it's a "free" mod but there must be a trade off.

I'm sure the trade off is fuel economy... and less snatchiness at lower rpm.

I know what Freeway voted dont i Freeway. I've just found out we know each other ,and he lives down the road .

Take a look at the fourth dyno output on this page

http://www.holeshot.com/dynocharts/dyno_bandit1250.html

The secondaries screw up air intake after 7000 rpm, they actually run a little closed so the engine will be starved some air above this. The blue dyno run is one with the secondaries on and the red is with the secondaries off, about 8 hp difference. The secondaries do help with down low torque however and so removing them will see a slight dip in power all the way up to about 5000 rpm, but only a midget's dick. I have mine on at the moment and don't plan taking them off until I get a new pipe;then again maybe not. It's a Bandit so just ride the torque curve between 4000-6500 and she's fine. If you do lots of full throttle, high RPM runs, then the secondaries are a fly in the ointment.

There is more than just the secondaries restricting output at the top end of the rev range. The dip and then jump at around 8 - 8.5k rpm shows there is something else he hasn't got rid of yet.

From the maps it is a combo of ign, fueling and secondaries. There could also be other things influencing this dip/jump at the end.

Thing is with the bike running as sent out by suzuki, the torque curve is pretty flat. Once all the add ons are added on (or removed in the case of the 2ndaries) the torque curve starts to get a bit lumpy with a bit of a hole around the 4k mark which for a lot of riders is where they ride most of the time

I agree that he gets some good numbers regarding improvement, but max numbers are not the full story.

dhula wrote:I agree that he gets some good numbers regarding improvement, but max numbers are not the full story.

For some the max numbers work. I did several hunderd km on Sat and they were all between 4,000 & 5,000rpm. A dip in that area is not what I'd want. Horses for courses

2wheelsagain wrote:

dhula wrote:I agree that he gets some good numbers regarding improvement, but max numbers are not the full story.

For some the max numbers work. I did several hunderd km on Sat and they were all between 4,000 & 5,000rpm. A dip in that area is not what I'd want. Horses for courses

+1.

x↑↑. Years has mellowed me. I'll be leaving the FA largely unchanged till warranty has expired, even then won't be all that much.

In this case, don’t believe information quoted by Geekay to be applicable in Gus's circumstance as the butterfly removal graphs/figures supplied rely on full stage 2 mods as an ensemble, not in isolation. Given that Gus has not gone down this moding path (gk, you werent to know this), removing the butterflies alone doesn't achieve Stage 2 quoted performance benefits.

Gus, the questions I'd be asking is what is your requirement, do you have a problem somewhere on your bike you want to rectify? R U looking for performance or economy benefits or do you just want to tinker with your bike? What do you hope removing the butterflies would solve?

Once you have your requirement/s, you can begin on the solution and ultimately, gauge your success throughout till completion.

p.s Perhaps someone has done butterfly removal mod in isolation who can share Gus with outcome +/- etc.. ?

p.s.s Stage 1 mods on my FA and absolutely no flat spot felt at all. Just a big

Hope this helps.
Mars

I went out yesterday and brought an "0" screwdriver to pull the secondaries .Its reversible and i dont mind pulling things apart .Buy ten last night
with a bit more study i'm wondering if i've made the right choice . Decided the best way to decide was while riding the bike .Went for a spin this arvo
and the first thing i noticed was how far up the dial 7 looked .Most people say the improvement is after 7 grand so, 7 grand here we come.
In third gear at 7 i'm doing 153 kph ,in 4th doing 180 kph ,in 5th i'm hanging on for dear life.I quickly realised the benefits for me are not there .
If i was going down the performance road maybe. I havnt even got a screen to hid behind (being naked),the benifits are to far up the dial for me .
For Sale -one unused screwdriver.

gus wrote:
For Sale -one unused screwdriver.

Left handed or right handed?

Pill 'em out Gus - You KNOW you want to .......

Is it that obvious .

Ah! but at least you know now!

gus wrote:Went for a spin this arvo and the first thing i noticed was how far up the dial 7 looked .Most people say the improvement is after 7 grand so, 7 grand here we come.
In third gear at 7 i'm doing 153 kph ,in 4th doing 180 kph ,in 5th i'm hanging on for dear life.I quickly realised the benefits for me are not there .
If i was going down the performance road maybe. I havnt even got a screen to hid behind (being naked),the benifits are to far up the dial for me .
For Sale -one unused screwdriver.

That's why I'm probably gonna leave them on

Mine's standard apart from K&N filter & Beowulf can with the secondaries removed. The slight loss in torque shown on Dale Walker's dyno charts is not noticeable at all mainly I think because it doesn't really exist. At lower revs the secondary plates will operate at a slightly different rate than the main throttles as the computer tries to compensate for our hamfistedness but we are perfectly capable of opening the throttle in a suitable manner, that is to say that any "loss" of torque is due to operator error. It's a bit like mechanical slide carbs compared to cv carbs.
Snap the throttle open too suddenly say Mikuni roundslides at low rpm & it's easy to fall into a big hole until the intake velocity recovers, whereas with cvs the slide is vacuum controlled & will respond smoothly. I removed the secondaries simply because it offends me deeply that when I open the throttle fully "computer says no" & shuts it down to about 70%. Outrageous!!! Power wise it no doubt helps a bit as is but to really get the benefit out of it would require some degree of compensation in the fuel department, so I'm eyeing off a Healtech FIT module at some stage in the near future.

I've heard your an ex motor cycle mechanic.?

Retired (??!!)