Carb main jet / extractors

[Dr.Roob]

Hi TV heads,
when i got my 88 hi ace about 6 mnths ago, 1st thing i did was put new plugs in. i noticed they were a light grey colour indicating running a little lean. After having bought a very stock and very tidy 85 model and driving it a little (I prefer the 88 - she’s rattier, but much more funky, in a good way), I’m pretty positive that the exhaust system on the 88 is a lot more free flowing. That would definitely account for running leaner. Does anyone know off hand what the standard main jet size is for the carb on a 4y engine and any suggestions as to how much higher would be suitable. The intake filter is stock.
Cheers - doc

[Burntboot]

Hey Doc - We never got Carb'd 4Y's on this side of the pond.

However, you probably don't need to re-jet, just need to access the mixture screw, a stock engine won't be able to exceed the supply abilities of the factory jetting.

When we did have carb'd cars, after they were set-up at the factory, emission rules required a cap to be installed over the mixture screw, to eliminate "tampering".
Finding and carefully removing that cap revealed the mixture screw, 1/4 - 1/2 a turn out was usually all that was needed, to make things right in the world again.

If the screw is capped, its best to verify location with a manual, sometimes there can be plugs that look right, but aren't (btdt), so always best to verify before attacking.

I preferred to remove the carb and pull the plug on the bench, sometimes they are hard to access and drilling too deep is a VERY bad thing, besides having the carb off lets you snug all the body screws, just have a fresh baseplate gasket (or 2) on hand.

[boogieman]

not sure what kind of carb we're talking about but if richening the mixture screw doesnt take care of it, in the moto world shimming up the needle will help richen up the rest of the circuit..ol