10 replies to this topic

[neon1991]

has anyone successfully re-bushed a HS4 carb?? what tools did you use?  I have a pillar drill but no access to a lathe...

 

[Spider]

Yes, just did one the other day in fact.

 

I have a Machine Reamer (as opposed to a Hand Reamer), with a Long Shank to bore out the Carb Body for the new Bushes. 

 

I drop the Reamer through the Spindle Holes back to front, then the Spindle aligns the new Bush Bore dead on with the other Bush. I do them one at a time.

 

Prior to purchasing the Reamer, I had done them in the Drill Press using an Angle Plate to clamp the Carb Body to, then a new Spindle in the Drill Chuck to align the Carb Body before clamping it up to the Angle Plate, then drill the Carb Body to take the Bush. I went away from this as the Drill Press is simply not precision enough to do this as it was hit & miss I found.

 

I don't have a file photo, but can post one up later.

[Spider]

Said Photos;-

 

 

 

The Reamer size is 0.375" Cutter, with a 0.310" Shank. These are a standard off the shelf size.

 

I fitted the adaptor on the end (with the grub screw), that I use to turn it with and also it's set as seen, as a depth stopper.

[ACDodd]

This is how I do it and it works very well. Need a slow turning pillar drill for reaming. 120rpm is ideal. Drill out first to 0.3mm under finished size, then team to 9.5mm (not 3/8") it's too big.


Ac

Attached Files

•  IMG-20180723-WA0004.jpg   38.35K   7 downloads

Edited by ACDodd, 17 August 2018 - 12:14 AM.

[Retroman]

A 940 jig I like it... assuming you run through both sides

 

Do you find the bushes need a reamer too ?

[Spider]

 then team to 9.5mm (not 3/8") it's too big.
 

 

 

Respectfully AC, SU advised me on the correct Reamer year ago and it seems the bushes haven't changed;-

 

"As a guideline 0.3125" internal diameter ream body to 9.55mm."

 

(9.55 mm = 0.3759")

 

http://www.minispare...ck to catalogue

 

When Reamed to 0.375", they are a press fit in.

 

 

 

Do you find the bushes need a reamer too ?

 

They shouldn't need Reaming after fitting

[ACDodd]

With respect to you, please check again, the manual states, 9.5mm.

Although the manual is wrong on the smaller bush for the HS2 carbs as it states 8mm. In actual fact it's 5/16". The bushes I have here are all 7.98mm in diameter.

Ac

Attached Files

•  IMG_20180817_091157.jpg   30.57K   6 downloads

Edited by ACDodd, 17 August 2018 - 08:29 AM.

[Retroman]

With respect to you both

 

Whats  0.001968504"  between friends ?....it's a gap....hahha

[neon1991]

hmmm I think Ac's drill press is slightly more accurate than my wobbly clarke jobby.  Carb is coming off this week to see the damage.  my problem seems to be occasional weak spot at about 60mph.  some days it's good,  other days it's bad.  generally the mixture is spot on so think it might be sucking in air.  if you floor it at 60, it pulls through the flat spot and other times there just isnt a flat spot.

 

after looking at the pics,  I'm hoping it's just cr@p in the bowl  

[neon1991]

thanks for the info by the way! it's handy to have those measurments

[Retroman]

Is it a standard engine etc ?

 

You should be able to feel any play in the spindle with the carb still on

 

It tends to affect things more at tick over

 

Any idea if its been rebuilt or how many miles ?