I'm installing a bugpak exhaust system and just relised that the holes for the two skinny pipes that come from the manifold are blocked on the exhaust system.
Are they necessary or is it ok to leave them blocked


thanks

I believe that they are okay as they just use the radiant heat off the exhaust pipe.

thanks mate, what are they used for anyway

Definately drill them out

They're just left undrilled from the factory so they can be used with twin carbs

You'll end up with a pig in winter if you leave it undrilled

Extractors with preheat dont work terribly well as both side are positive pressure inlets where as stock only has one but it's still better than none at all

Fuel only burns properly as a vapour and going from a liquid to a vapour in the carb causes a refrigeration effect and the manifold ices causing really poor running
heating the manifold helps keep the fuel suspended as a vapour and stop icing

Depends what carburettor you are running

If you are running duals leave them blocked

A single............hmmm...............Leppington................cold winters

The hard part is the undrilled ones are at an angle
REALLY dard to drill out