7 replies to this topic

[jpw1275]

Hi all.... Does anyone know the thread and size of these little screws as I'm after getting domed screws to replace the standard ones, these are to fit twin hs2 carbs

Cheers james

Edited by jpw1275, 26 June 2014 - 06:23 PM.

[Stu1961]

Not sure but it may be BA though sure of the size

[mini13]

I think they are BA, but in the past I have had success in stuffing an M3 tap through and using an M3 screw....

 

when I did this I was "vizarding" the carb, cutting away the top half of the spindle, countersingking the butterfly, and slimming the rmaining (threaded ) part of the spindle. I would skrew the butterfly on and grind the screw flush woth the spindle, then reasemble in the carb with loctite and use a centrepunch to stake the screw intpo the spindle.

[rally515]

I think Somerford might be able to tell you if you can get in touch with them on the phone J.

http://www.somerford...oducts_id=13523

 

http://www.somerford...age=page&id=166

[carbon]

They are Whitworth thread, will try to get back with the size. I think there is a very similar american thread.

[jpw1275]

I've bitten the bullet and gone for BA5 as they where only cheap

[carbon]

The butterfly screws are 1/8 inch Whitworth thread, this has 40 tpi.

 

The American UNC 5-40 thread is very close to the 1/8 Whitworth.

[jpw1275]

Hi all.... BA5 fit just fine.... I went for flat heads and 1/8" in length..... Also countersunk the screws in a little aswell





Cheers James

So if anyone wants any new screws for there butterfly shafts and using twin hs2's then BA5 fit

Just remember to thread lock them in.... 1/8" does not protrude out of the other side of the shaft

And are a million times better than the original screws regarding airflow

Edited by jpw1275, 28 June 2014 - 02:03 PM.