Fitting SU HS4 carb Spindle bushes

[@fetlocks3]

Very interesting, thank you.

[@joe909990]

Great stuff...

[@alanvinegar5729]

Surprised you cut all the way through. I would want to maintain the factory inner body throat to avoid air leaks.

[@ACDodd]

This makes the carb the same as the later HIF carbs. This way you can check the bushes DIY after this modification. So long as the bush is put all the way in the air leak is not noticeable

[@alanvinegar5729]

@@ACDodd take a look at this youtube by Joe Curto for a better idea of what I was referring to. He does suggest a fix by drifting the bush through and then trimming it flush with a drum sander. kzbin.info/www/bejne/j5bYXqdvpM-neMU

[@ACDodd]

@@alanvinegar5729 Yes I understand, but it’s not required. If it was the later carbs would have been done the same way

[@ptirom44]

Very interesting! What are cutters diameters? If I understood correctly, you don't need to drill HIF carbs?

[@ACDodd]

Hif carbs do not need machining. 9.2mm drill and 9.5mm reamer

[@ptirom44]

@@ACDodd thank you!

[@demiquadfpv3333]

Please can you describe what the driving symptoms be if there's excessive wearing / air leakage from the hs4 spindle bush. Thanks

[@ACDodd]

Usually shown up as erratic idle speed (not always the same) engine cutting out when you slow to a stop, inconsistent air/ratio leading to irratic idle etc.

[@bogdanpopa6215]

if you do not know how to do it, do not pretend this is a good solution !!

[@ACDodd]

That’s not my view or experience

[@user-gl5kj1fm5x]

its the only SU approved solution