Breezy Airbox

[MisterCinders]

I see the recommendations to seal up, weatherstrip, etc. the airbox.

When I changed my air filter this weekend (1978 GS750), the side covers seemed pretty tight. Once the old filter was out, I could see that there is a large opening in the rear of the box. It's about 3 inches, but looks deliberate. Not a crack or missing chunk, but a specifically cut notch. I'll try to remember to snap a pic later.

Is this right? Is there a piece missing? Seems odd to have a big opening there, given everyone's emphatic calls to seal that box up.

[tkent02]

There is supposed to be a rubber snorkel there, it is more like an intake muffler I think.
The carbs are calibrated to run correctly with it in place, might be too lean without it.

[twr1776]

Today 01:41 PM tkent02 There is supposed to be a rubber snorkel there, it is more like an intake muffler I think. The carbs are calibrated to run correctly with it in place, might be too lean without it.

+ 1, it is likely too lean and usually will also have a big flat spot between 3 - 5 K when you roll the throttle hard. E-bay for a used airbox with one still in it is probably the easiest place to fine one.

[MisterCinders]

Hmm, where might I find one of these parts? Came up short at Z1.

[tkent02]

You have a 1978 with VM carbs, they are not so sensitive to intake restrictions and they are easier to tune than the later CVs. It's probably easier to rejet the carbs than find that snorkel. If you have this flat spot, try going up to the next bigger main jet, then do plug chops to see if you got it right.

Z1 sell the jets, I believe your bike comes with 102.5 stock, so 105 would be the next larger jet.

You never did mention how well it runs now.

[Larry D]

I think the snorkel will look like this.

[Adler]

According to the fiche there is no snorkel...

http://www.alpha-sports.com/suzuki_parts.htm?fpg=/spst/1978%20GS750E/01.htm

My friend got a '78 750 and it came with 2 airboxes... no snokels. Ive also looked on ebay and found nothing.

[MisterCinders]

Wierd. So the back of the box is supposed to be open? Or did someone swap the box on this bike? The diagram does not show the back of the airbox where the notch is. Could it be a solid piece on that year?

[MisterCinders]

Also, what is the difference between the 1978 GS750C and 1978 GS750EC?

[MisterCinders]

You have a 1978 with VM carbs, they are not so sensitive to intake restrictions and they are easier to tune than the later CVs. It's probably easier to rejet the carbs than find that snorkel. If you have this flat spot, try going up to the next bigger main jet, then do plug chops to see if you got it right.

Z1 sell the jets, I believe your bike comes with 102.5 stock, so 105 would be the next larger jet.

You never did mention how well it runs now.

It runs a bit rough, but I need to do valves, carbs, etc. Hitting that next.

[koolaid_kid]

Also, what is the difference between the 1978 GS750C and 1978 GS750EC?

C had a single front disc and wire wheels. EC had dual front discs and mag wheels. Other minor differences, but those are the two biggies.

[MisterCinders]

C had a single front disc and wire wheels. EC had dual front discs and mag wheels. Other minor differences, but those are the two biggies.

LAFFO!

My bike has single front disc brake and mag wheels.

[Adler]

Both the airboxes my friend got had that hole, I think he also has single disc and mags.

[bwringer]

According to the fiche there is no snorkel...

http://www.alpha-sports.com/suzuki_parts.htm?fpg=/spst/1978%20GS750E/01.htm

My friend got a '78 750 and it came with 2 airboxes... no snokels. Ive also looked on ebay and found nothing.

Whatchoo talkin 'bout, Willis?

In that diagram, you can see the upper edge of the snorkel peeking out from the back of the airbox, beneath parts 11, 12, and 13.

The snorkel is not available as a separate part, but it appears this motorcycle did have one from the factory.

And yes, it is tragically common to find that misguided POs have removed the snorkels, thinking it'll somehow improve performance. It does not. Quite the opposite, in fact.

As noted above, it might be easier to rejet than to find a good snorkel. They are depressingly rare, although a plea in the parts wanted section may get results.

[Adler]

Whatchoo talkin 'bout, Willis?

In that diagram, you can see the upper edge of the snorkel peeking out from the back of the airbox, beneath parts 11, 12, and 13.

The snorkel is not available as a separate part, but it appears this motorcycle did have one from the factory.

And yes, it is tragically common to find that misguided POs have removed the snorkels, thinking it'll somehow improve performance. It does not. Quite the opposite, in fact.

As noted above, it might be easier to rejet than to find a good snorkel. They are depressingly rare, although a plea in the parts wanted section may get results.

ooooh THAT snorkel!
Really though? Thought that was just an edge of the airbox... looks like I'll have to tell my friend to add that to the list of things to get...