1982 Shovelhead FXRS carb question

[klammer76]

A friend just picked up a 1982 FXRS. Bike is in reasonably good shape for sitting for a while and it's age. He is doing a restoration on it. Been a while for me and shovels (mine was a 1975 with a Bendix) and FXR's. Question, bike has a Keihin butterfly carb. carb appears to measure 42mm (41.96 where it connects to manifold). I have never heard of a 42mm Keihin. Was there ever a 42mm? Bike has been worked over a bit, someone removed the electronic ignition and converted back to points so who knows. Carb needs a new float but hard to find. He was able to seat the old float and the bike fired right up.

Any idea on this carb?

Thanks for any info.

[kd]

I just searched Harley Keihin carburetor identification and there's lots there.  Without having the carb and markings there's no point in going further for this guy.  Have you tried an internet search yet?

[JW113]

Put a CV40 on it. Can't go wrong. Why not?

-JW

[Winston Wolf]

You have a picture of it?  They had a bigger "Screamin Eagle" version that is a slightly different design, has a little enrichener plunger instead of a choke connection. I have one on the shelf if you need to compare. Parts are easy to find for either, Dennis Kirk stocks full rebuild kits, jets, etc.

[Buglet]

  Those Screaming Eagle carb's did run good. I still have a new in box kit. 

[klammer76]

I just searched Harley Keihin carburetor identification and there's lots there.  Without having the carb and markings there's no point in going further for this guy.  Have you tried an internet search yet?

I have done multiple internet searches and find nothing with regard to a 42mm Keihin.

[klammer76]

You have a picture of it?  They had a bigger "Screamin Eagle" version that is a slightly different design, has a little enrichener plunger instead of a choke connection. I have one on the shelf if you need to compare. Parts are easy to find for either, Dennis Kirk stocks full rebuild kits, jets, etc.

That would have been their SE 44mm I believe. There was one bigger also. Both CV's and for TC's as I recall.

[klammer76]

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[cheech]

Since those were butterfly venturi type carbs.
Were those classified back then by the bore you're measuring or the venturi diameter? 
Clearly the latter being smaller.

[klammer76]

Unsure. I guess a measurement of the throttle plate would tell. I believe the stock 82 carb was a 38mm?

[kd]

Not a carb but HPI has tested and is now producing throttle bodies with a different throat size from the throttle plate to the final throat size.  An example is the 62/64 MM TB.  With the short Harley manifold and the pulse interference of cam overlap the larger volume on the manifold side of the throttle plate appears contributes to manifold volume to reduce the pulse strength and enhance tuning at lower RPM.  Is it possible some of the performance versions of these carbs are built that way too or the carb you have has been bored?

[klammer76]

Not a carb but HPI has tested and is now producing throttle bodies with a different throat size from the throttle plate to the final throat size.  An example is the 62/64 MM TB.  With the short Harley manifold and the pulse interference of cam overlap the larger volume on the manifold side of the throttle plate appears contributes to manifold volume to reduce the pulse strength and enhance tuning at lower RPM.  Is it possible some of the performance versions of these carbs are built that way too or the carb you have has been bored?

Don't know, not my carb. Friends bike.

[cheech]

Unsure. I guess a measurement of the throttle plate would tell. I believe the stock 82 carb was a 38mm?

It appears to me that was where you were measuring?
My point was the venturi probably is 38MM perhaps if the throat where you are measuring is 42MM.

[RTMike]

Looks like a stock Kihei carb from that time frame.