Converting 550sx to PJS Intake Manifold & Mikuni SBN 44 ?

[E350]

The crank case on my 1993 Kawasaki 550sx filled up with fuel again.
I understand that to fix this problem I need to replace the seat and needle in the Keihin carb.

But I feel much more comfortable working on Yamaha oem Mikuni Super BN 44 carburetors.

So, I am considering converting the 550sx reed engine to a Mikuni Super BN 44 carburetor.

Is all I need a PJS intake manifold and an SBN 44 or do I need more?

Where should I buy the PJS intake manifold?

Where should I buy the SBN 44?

Note: I have a Yamaha 650 engine I can remove the carb from. (However, I hate to start cannibalizing a perfectly good engine, which I may sell or use elsewhere.)

Is there anything else I need? Is a re-jetting required?

Any suggestions for parts and info?

(I have done a search but haven't found anything too definite yet.)

@Aquaholic @waxhead @john zigler

 

[Aquaholic]

Any Hot products dealer can get you the WarecraftWerks manifold. John at Watcon is also an excellent source. Have him also get you a new SBN 44, as well. And, intake gaskets.
You'll also need a flame arrestor adapter and a flame arrestor.

As far as jetting goes...what elevation are you riding at? You can get ahold of me and I can give you a good starting point.

 

[fastgtfairlane]

There's also a little adapter you can buy to bolt the sbn on the stock manifold. If you can find a reed cylinder single 44 manifold. It'll probably not be cheap. Jetting will probably around the 100-110 pilot, 110-120 main, 20-25 psi popoff depending on which flame arrestor you choose.

Keihins are not difficult to tune or rebuild, the issue is availability of parts and jets to tune it more than anything.

 

[E350]

Perfect. Thank you. I am riding at at 13-17 ft. above sea level -- depending on the tide...


Note: Flame arrestor has long since been changed to stock. Fuel lines have all been replaced. Wax Racing Products internal fuel fill has been added.

 

[Quinc]

Pretty option:

Intake Manifold for Kawasaki 550SX Reed Engine (Single SBN 44mm)

Intake Manifold for Kawasaki 550sx reed engine model skis. This manifold enables you to use a new Mikuni SBN 44mm carburetor. Intake Manifold for Kawasaki 550SX Reed Engine (Single SBN 44mm) by PJS from Vintage JetSki.

vintagejetski.com

Cheap option:

Keihin to Mikuni Carb Adapter

Adapt a Mikuni SBN 44 to your OEM 550SX intake manifold with ease to maximize your motors efficiency. Made from 6061 aircraft aluminum.

vintagejetski.com

 

[WFO Speedracer]

That carb adaptor works fine, bolt it on the manifold with no gasket then take a sanding drum on a die grinder or a drill and match the intake to the adaptor, then assemble it.

 

[E350]

It's interesting. The PJS accelerator cable bracket is on the wrong side for my ski.

Or does the SBN have to be reversed to fit in a 550sx hull?

I notice that @Aquaholic 's SBN is reversed (with fuel pump outboard) from how it would be oriented in a SN SJ or FX-1 (with fuel pump inboard).

The carb adapter has no accelerator cable bracket. So I assume an aftermarket bracket would have to be used with the carb adapter?

(Or do I have a carb adapter bracket under my existing large Keihin anyway? I will have to check.)

 

[WFO Speedracer]

You can use the 650 SX style that bolts to the motor mount or use one off a Yamaha 61X style that goes under the carb, it will have to be modified slightly for the bigger Kawi throttle cable though, an ADA throttle wheel will sort the cable length issues out.

 

[Aquaholic]

The WatercraftWerks manifold is ambidextrous.

 

[E350]

@Aquaholic is this the manifold you used?

Billet Aluminum Kawasaki 550 SX Intake Manifold - WCW-550SXMANIFOLD

Billet Aluminum Kawasaki 550 SX Intake Manifold - WCW-550SXMANIFOLD

www.watercraftwerks.com

John Zigler's photo does not appear to have ambidexterous brackets:

Intake manifold Kawasaki 550sx REED engine

Single SBN Intake manifold for Kawasaki 550sx reed engine. Fits Single Mikuni SBN44-46mm carb. Comes as shown with mount hardware. Please email with questions before ordering.

watcon.com

 

[Aquaholic]

@Aquaholic is this the manifold you used?

View attachment 430716

Billet Aluminum Kawasaki 550 SX Intake Manifold - WCW-550SXMANIFOLD

Billet Aluminum Kawasaki 550 SX Intake Manifold - WCW-550SXMANIFOLD

www.watercraftwerks.com

John Zigler's photo does not appear to have ambidexterous brackets:

View attachment 430727

Intake manifold Kawasaki 550sx REED engine

Single SBN Intake manifold for Kawasaki 550sx reed engine. Fits Single Mikuni SBN44-46mm carb. Comes as shown with mount hardware. Please email with questions before ordering.

watcon.com

Yes.watercraftWerks. My bad. Senior moment.

 

[WFO Speedracer]

looks like watercraft werks is CNC machined and the other one is cast

 

[E350]

@Aquaholic Dude. You only use the best!
(and the most expensive...)
Not surprising given the beauty of your shop.

Also, might as well ask now, do you find a pipe to be helpful on a 550sx reed engine?
If so, do you prefer a full pipe or is a half-pipe sufficient?
And what pipe or half-pipe do you prefer?

Thanks @Aquaholic ! I would hope to stop by your shop if we are ever in So. Cal. again.

And thanks to @WFO Speedracer and @Quinc and @fastgtfairlane for your input so far.

I will be pulling the Keihin soon and flipping the ski to drain the crank case and I will likely try replacing the seat and needle in the Keihin while waiting for money for parts for the SBN conversion because I would like my buddy to ride with us before it gets too cold.


@WFO Speedracer I noticed that too. Basically it is $100 more for a CNC'd version with an ambidextrous throttle cable bracket.

 

[WFO Speedracer]

A long time ago, in a land far far away you could buy just the section of the Keihin carbs that contained the seat, alas those times are gone now and now all you can do is replace the needle, but I will give you a motorcycle tip we use a lot.

A lot of motorcycle CARB seats are not replacable either on those here is what we do, take a q- tip and dip it in rubbing compound, chuck the other end of the q- tip into a drill, now use the q-tip and rubbing compound to burnish the seat, you will notice when you pull out the q- tip it is now black, clean the seat up well with carb cleaner and now install the new needle , it should seal up nicely now.

IMHO intake manifolds on jetskis hold the carb on, they usually don't do much else, you can certainly spend as much on an intake manifold as you want to, and yes it will look really nice but you will be hard pressed to tell a performance difference from just an intake manifold change. The half pipe on the other hand will make a notable difference in low end power and it will pull about 1000 RPM's more on top end, it doesn't look as good as a full pipe does but on limited and recreational skis it works a lot better.

I used to run a 550SX with a Coffman half pipe and Westcoast manifold and dual Kehin 38's it ran really nice.

 

[kevbo]

A Mikuni SBN44 is on the large size for a reed 550. Im sure it will work as long as the rpm is high enough. You need to already know how to tune a carb before the "I need a bigger carb" game is played. If you ever have to ask others what jets to use then master tuning your Keihin first.

 

[E350]

@kevbo Fair enough, I do not know how to tune. So, your statement is likely spot on.

My next step is to remove and post up a photo of the seat and needle in the Keihin.

 

[fastgtfairlane]

I had dual sbn 38s on my 550 haha. It ran excellent

 

[waxhead]

Just buy the adapter unless you are trying to look good

 

[WFO Speedracer]

I set one up with an SBN 44, it ran really well also , not sure what Kevbo is talking about PP550s came with BN 44's , not sure why a reed motor with a lot more compression would have different carburetion requirements, trust me it will run fine on either a SBN 44 or dual 38' s, mine started off with SBN 38'S , then I switched to the westcoast manifold and dual Kehin 38's,. it ran much better with the Kehins than it ever did with the 38BN's.

 

[fastgtfairlane]

Really? I had the opposite experience on a pjs viper engine that originally had the dual 40mm keihins. Nothing at all against the keihins they're decent carbs, just the mikunis are easier to tube because there's more available parts to tune it. At least in my experience. But I know you worked at a dealer for a while so you probably had all the availability, not to mention that was probably years ago too haha