ET: Engine (Twin) Pilot jet

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Little Honda

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Yes... but did you test it on your dyno? #cashinthat401k

It should be noted here, that the study covers the total length of inlet between valve seat and air entry, not
the outer trumpet on the carb before the needle valve. Moreover, the shown bellmouth form is not the best
possible one: The entry profile should be surrounded by a 180° radius to get less entry turbulences.
 

oexing

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I like to have long bellmouths on my carbs, performance-wise a good total length of the inlet is no bad idea, look at Manxes and Goldstars with their substantial carb spacers plus bellmouths to achieve this. Modern fuel injected car engines have funny "bunch-of-bananas" induction pipes to get a real long effective length from plain air to inlet valves. That length is depended on the speed range of the engine, the higher revving the shorter the system can be.

Vic

IMG00013.JPG
 

Magnetoman

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It should be noted here, that the study covers the total length of inlet between valve seat ...
The situation with our engines is different than modeled by that study. The study assumes an unobstructed inlet tract from the trumpet to the valve but, other than full throttle, the slides of our Amals and Mikinis present a very significant obstruction roughly halfway along the tract. This makes modeling of the full h.p. vs. torque curve for our bikes more of a challenge.
 

Cyborg

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It should be noted here, that the study covers the total length of inlet between valve seat and air entry, not
the outer trumpet on the carb before the needle valve. Moreover, the shown bellmouth form is not the best
possible one: The entry profile should be surrounded by a 180° radius to get less entry turbulences.

Duly noted. I should probably also note that I just attached the first thing I came across. I know this makes me a bad person, but it was just a thinly veiled attempt to rattle his cage.
 

Cyborg

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It should be noted here, that the study covers the total length of inlet between valve seat and air entry, not
the outer trumpet on the carb before the needle valve. Moreover, the shown bellmouth form is not the best
possible one: The entry profile should be surrounded by a 180° radius to get less entry turbulences.

At least for me, a good example of that was (back in the dark ages) I was asked to jet a CB750 with a “custom” air box and headers that had been installed by the customer. Long story short, it simply wouldn’t behave until I took the rubber stacks out of the stock air box and installed them in his custom contraption. Seems like velocity stacks are more critical on some carbs than others.
 

Bill Thomas

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They had trouble with one of the Jag's , Many years ago, And the factory cure was a small plastic bellmouth,
Pressed onto the airbox.
 

erik

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Today the Pilot jets in different sizes arrived.But weather changed to really bad and it can take time until I can test it.but I will tell you my experiences.Erik
 
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