Carb Interchange

[Aches n Pains]

After looking at a whole lot of different threads it looks to me as if I can mount a set of carbs off a 1978E on a 1980G. Recognize that the bowl vent will be different and that I will need to use the jets from the '78.

Do I have that right?

Thanks,

Doug

[natemoen]

All the carbs racks interchange between years. You must jet according the the year of the carbs though, NOT the year of the bike. Then when getting parts you need to make sure they are for the right carb year and not bike year.

[crazy steve]

Recognize that the bowl vent will be different...

The nipples for the vents are on all the airbox assemblies, just not drilled on the later units. Drill a 1/8" hole through the nipple and you'll be good to go...

[DGXSER]

Nit picky detail perhaps, but on the older airboxes, the vent nipple has a metal sleeve in it. That sleeve is not there on the newer style that are nto drilled. As Steve suggested, drilling the hole through the nipple will work fine.

[crazy steve]

Nit picky detail perhaps, but on the older airboxes, the vent nipple has a metal sleeve in it. That sleeve is not there on the newer style that are nto drilled. As Steve suggested, drilling the hole through the nipple will work fine.

I thought about that, and I'm not sure just why they did that. That would put the 'inlet' into a higher-vacuum area, so I suppose that would help with fuel flow under certain conditions. A visit to a hobby shop and some 1/8" OD brass tube would fix this if any issues turned up....

[bikerphil]

Been running my 79SF with the 80-81 air box and the ports drilled out, no problems.

[DGXSER]

I don't think it would have any effect on the bike running. Just a subtle difference, my anal retentive nature just had to point it out.

[BA80]

I have a set of 79 carbs on my SG. Ran them with the original engine until it developed a knock and they ran great. Much more adjustable and easier to adjust. I have a 79 engine in Ol' Okie now also. It runs a LOT stronger than the 80 engine.

The airbox is no problem. I did the same as bikerphil and it works perfectly. There is no "vacuum" to speak of there.

[Aches n Pains]

Thanks, guys. I like the 78/79 carbs better also.

[oldnortonrider]

Thanks, guys. I like the 78/79 carbs better also.

I like 'em because they use the brass floats; those alien material plastic "type" floats make me nervous. And, I'm not all that keen on the viton tipped float needles. (Given that I would have a choice.)