Be cautious with the CNS ported intakes

[45u]

We have an offset intake manifold as well that works really well .
It's a three-piece kit with a vibration dampener in between a lot of complaints have come through with stock intake manifolds breaking because of vibration so we separated into three pieces to melt aluminum Barb pieces 1/5 motor side one fits carburetor side and a rubber dampener in between the two that keeps it from breaking off I agree the Mikuni's are the way to go

With the hose in the middle does not seem like you would have very smooth air fuel transfer.

 

[45u]

OK I asked this once but will ask in a separate post in hopes I get a reply. Those that are running the VM 18mm Mikuni are you running the stock slide? If not what number cut out are you running?

 

[GhettoBike]

works like a charm

 

[Nanonevol]

You've heard the debate about smooth vs rough intake vis a vis atomization of the fuel, etc.?

 

[45u]

You've heard the debate about smooth vs rough intake vis a vis atomization of the fuel, etc.?

Yes, you do not want the intake smooth as a piece of glass like the exhaust port. Yes, you want atomization but you sure do not want abrupt steeps or rough casting marks like most of the manifolds sold with JUST a hose. If you look at motorcycle carburetor systems that use a rubber fitting between the carburetor and motor, you will see they are made where there is not ANY abrupt steps as this is not good for flow. I am sure those for motor bikes that use a hose work but I bet if you put them on a flow bench they do not flow very well!!!!!! May will polish the intake to a port then blast the inside to give it some roughness to atomization. For those that do not know what atomization is it is getting the air and fuel to mix well before entering the engine.

 

[inspectorcritic]

I will not say with 100% certainty that the ported intakes for the CNS from pirate cause both of these carbs to break in exactly the same place a couple days after installing them on two different intakes, on two different bikes, but I think it is highly coincidental.

I'm not trying to badmouth them at all because they are a great company. I think that maybe this is either a fluke thing that happened with my carbs because they had been tightened down so much on the regular intakes using the white collars that come with them, or maybe it's because they are relatively new intakes, so there hasn't been that much customer feedback on them yet. Either way I think I should share my experience and let others know that there is at least a possibility this may happen. Like I said, I just think it is too coincidental to dismiss.

It's a shame because the intakes fit great. I think that the metal of these carbs is so weak that they are just prone to breakage from vibration- also prone to vibrating off the stock intakes completely. The mouth of the carb (if that is what you call it?) is relatively short and very wide.... and the carb is heavy so that doesn't help either.

Take a look at where they broke and notice the same pattern. My guess is that the white collar that comes wit them helps protect the carb from the direct vibration. When you remove that collar and you put all of the force (and vibration) directly on the "mouth" of the carb on that wide intake... I just think the vibration is too much for it to handle.

Please take this FWIW... and I'd appreciate any other hypothesis as to why they both failed like this and maybe something that could be done to lessen the likelihood of it happening?

These carbs aren't cheap and I have a whole box of broken carbs and parts possibly for sale, but that is another thread. I really like the extra torque they provide, but I would find myself adjusting the carb almost every ride.

 

[inspectorcritic]

I don't know if its the same ccarb I bought a GT 80 4.5 HP ported some as***le swipe that black disc that goes in the carb what is it can I run without it? If its a gasket can I make one?

 

[Deleted member 12676]

irregularities in the intake tract aren't very important at rpm below 9000.

I too have the Mikuni VM18 and highly recommend it.