Carb settings

[Gsxr750m]

Got a b12 engine and will be using 38 mm slingshot carbs with twin ram air filters and cobra 4into 1. Has anyone got settings for carbs i.e. Pilots mains and needle height, cheers

[wraith]

I'm running 38mm on my 1127 with 150 mains, 3 1/2 turns out on the pilots and dropped the needles to the 2nd groove from the top.

[Gsxr750m]

Cheers wraith that's all I needed a starting point running like a bag of shit at mo

[boilerdude]

it could probably use 35 pilots or 37.5 . the 32.5 as stock on a 91 gsxr 750 is a bit on the lean side for off idle performance on the bigger bikes.

 

[boilerdude]

If you're using the 750 boots to the engine you may want to do some grinding on the ports so they match up better. 

Stuff ports with paper towel. Leave some sticking out so you can grab it. Then also seal the stuffed ports with grease as well. This will catch the shavings. And you can just pull it all out when you're done.

And now you're ready to do some mild port matching. Use the twisty tool with a grindy thing on the end of it.

[Gsxr750m]

Thanks for info I am using 38 boots so will get them sorted too

[boilerdude]

It will run fine without the port matching. But you will see what I mean when you put the boots on the motor and see how they match up. 

I know cylinder #1 is waaay off on mine still. need to do some grinding.

But be super careful to seal off that port good and generous with the grease and get all them shavings outta there. Only attempt the porting yourself if you are confident about that part. Metal shavings bad for motor.  That is my disclaimer.

[Nelson]

Slabside motor, 38mm powerjet carbs, Dynojet carbs, Pipercross duals.

134 mains

3rd clip

Hope that helps.

[Gsxr750m]

Yes I'm ok doing a bit of fettling just need to get of me arse now this Christmas malarkey is done and get on with it, all info helps guide me in the right direction nelson, cheers guys 

[boilerdude]

On 12/31/2016 at 3:55 PM, Nelson said:

Slabside motor, 38mm powerjet carbs, Dynojet carbs, Pipercross duals.

134 mains

3rd clip

Hope that helps.

which dynojet kit? for a 750m? and which stage. 

Also which filters. My ramair duals are deteriorating where my knees rub them because they dont fit good. Wouldn't mind trying something different.

[boilerdude]

http://www.Eblag.com/itm/Pipercross-MPX1004-Suzuki-GSX-Katana-GSF-Yamaha-FZR750-Power-Cone-Air-Filter-/191977476449?hash=item2cb2bfd161:g:ojsAAOSwPCVX47xy&vxp=mtr

found the filters. jesus. well they do look high quality i reckon.

[Nelson]

Hi Dude,

I had K & N's but the fit is terrible, you either have to crush them down or notch them

Even then they look crap & stick out

 

So I found the Pipers.

Piper have been around forever.

When they turned up they seemed good quality & at that price, you don't have to clean them, you can just get new (maybe not).

Its the stage '3' kit for open pipe no air box for the 750m.

Its a big kit, new emulsion tubes, new springs, drills for the slide. Real scary stuff but if you've used them before, its straight forwards enough.

The main jets that come with it are too big & the dyno man just kept going down until it was right.

He reckons they probably set the jets big so it doesn't run lean & damage the engine.

The kit is about 200 quid & a million hours on the dyno.

Here's how it looks now.

 

Someone on the site put me onto them

Loads better, doesnt take your knee caps off & runs shit-hot.

Sorted Dude.

  

 

[boilerdude]

no expert here but I reckon those look like they might flow considerably less than k&n or ramair. which might be a good thing?

[Nelson]

I thought about that too.

I figured that its sucking through a 38mm hole, one intake at a time & that dual pod has a much bigger surface area than a 38mm dia carb mouth.

Suction only goes down to a vacuum, unlike pressure.

I couldn't see it getting near restricting the air flow.

They will probably need cleaning more often.

The shot with the K&N's are on 40mm 1100M carbs.

They made 130 brake at the back wheel.

All the internet people say the 38mm power jet carbs are the big I am.

Just had it sorted in December, perfect timing.

they make 125 brake at the back wheel & a tiny bit less torque, can't remember exactly now.

The 40mm's were real hard work to live with but they were well fecked.

Its not the best time of year for balls out, back to back testing, but the 38mm's have made it very nice to scoot about on, motorway commuting filtering, making 'progress' etc.

As best I can tell.

There's all that thing about smaller diameter giving higher air speeds, blar, blar, blar.

Smoke & mirrors, Maths & unicorns.

However, IT'S FECKING SORTED NOW, at last.

Let us know how it works out.

Good luck, Dude.

[boilerdude]

Those are damn decent numbers for a 1052. did you match up the ports at all? they had to have been way off on that motor...

[Nelson]

Good numbers cheers Dude, 

The inlet rubbers were blended for the 40mm's & the head.

The 40's & the 38mm's are the same external dia & I was losing the will to live so I haven't blended the inlet side of the carbs yet.

Will get round to it, might be a bit more to come for free. 

But it makes me wonder what the 40mm's would have been like if I had thrown the money at them.

Oh well, only one way to find out, maybe !

 

[boilerdude]

Or you could send those 40s my way and I could try them out   

Trade ya a set of bandit carbs... untouched. brass plugs still there.

[Blue]

What about 750WN carbs for jetting on an 1127?

[Nelson]

Hey, cheers for the offer Dude, however, when I recover from the bill, I think I'll give the 40s a go.

In theory there's at least 5 horses in there just for the jetting, maybe more when setup right.

Blue, my Slabby has a mild bore in it so its probably very similar to yours.

Can't see there being that much difference in the carbs, so if you put a Dyno-jet kit in, the jets can't be that far out.

Sorry not to be more help, good luck.  

 

[boilerdude]

curious blue. what combination of intake boots are you using?

[Blue]

Not sure, possibly 1127 rubbers that I think 2 of em are upside down or swapped from side to side, I really can't remember! I guess it's my age!

[Gsxr750m]

Finally got my carbs sorted all new kits in and still leaked fuel found out one of the needles was different , sorted now fitted them at weekend just need some decent weather now to try them out