Missing stock air-box cover - Issues?

[bbutler455]

Almost done with my 82 Kat. It is missing the cover for the stock air box. What is the impact of running the box without the cover. I have Yoshi 4-1 pipes and a KN OEM style filter. Should I try to fabricate a cover or will it run better without one? Does anyone have one of these critters laying around?

[dcil]

Very good possibility that it would run lean. If you can't find one, you could always make one out of abs plastic or sheet metal. Quick and easy.

[Roger P.]

I took the cover off my stock airbox on my 83 1100e and it seemed to generate quite a bit of hesitation during acceleration, probably due to reduced vacuum on the diaphragms.

[gearhead13]

I am pretty sure I have an airbox lid around here somewhere

[rapidray]

The hesitation caused by running without the airbox lid is called a LEAN CONDITION!!! You fix it with a jet kit & the correct jets for what the bike wants to run correctly. Ray.

[koolaid_kid]

My GS came without a cover and ran lean. I used duck tape for a while, then got some ABS plastic and two sided foam tape and made a nice cover for it. The OEM covers are usually made of unobtainium.

[rcoville]

My 83 GS 1100 ES came without one when I bought it and I have never thought anything of it. I have a 4 -in - i header, yosh exhaust and K&N air filter. Since I bought it, I have put just over 10 k kms on the bike. Never had any hesitation and it runs beautifully.

BUT after reading all the other replies here, I may cobble up a make-shift cover this weekend and run the bike with it for a week to see if I notice any difference. I'll report back if I see anything from it of importance.

[koolaid_kid]

If you rejet for the extra air, there would not be an issue. Perhaps the PO did just that, IDK. My bike was totally stock, so the jetting was lean with the lid removed.

[bbutler455]

I am pretty sure I have an airbox lid around here somewhere

Outstanding! Is it the type for the top of the airbox? Here is a diagram of the top I will have to fabricate if I can't find one. If yours looks like a fit, send me a PM and let me know how much you want for it.

[bbutler455]

If you rejet for the extra air, there would not be an issue. Perhaps the PO did just that, IDK. My bike was totally stock, so the jetting was lean with the lid removed.

When I rebuilt the carbs I installed the Dynojet kit for stage one. I used the 118 main jets because I had the Yoshi pipes. I haven't run the bike yet to know whether I have a problem. I restored the bike to museum quality so I would really like to find an original cover.

Just out of curiosity, if jetted correctly, does the bike run better without the cover?

[koolaid_kid]

When I rebuilt the carbs I installed the Dynojet kit for stage one. I used the 118 main jets because I had the Yoshi pipes. I haven't run the bike yet to know whether I have a problem. I restored the bike to museum quality so I would really like to find an original cover.

Just out of curiosity, if jetted correctly, does the bike run better without the cover?

Better is subjective. An engine is an air pump. Allowing it to pump more air will increase the power it can produce. If jetted correctly, a totally stock engine will produce slightly less power than an engine with the cover removed and jetted correctly for the increased airflow.
However, there are so many variables in the equation; individual engines, their conditions, elevations, fuel qualities, etc. that it may be difficult to determine. IMHO, each engine must be dynoed by itself to see what works the best for it.
If you are going for the most power, go with pods, a pipe, and a DynoJet kit. And a dyno tune, coupled with a street tune.

[Roger P.]

An extensive write up on the GS1100 in a magazine article linked from here awhile back stated a 2hp increase with the lid removed, if I recall correctly.

Thanks for the diagnosis Ray. Lean doesn't surprise me, as I think this bike of mine was running lean from the get go. I have a sneaky suspicion that it isn't completely stock, given that I can see a multi-layer steel head gasket in there. It tends to ping a bit too.

You can tell how much fun I'm going to have setting up whatever carbs I end up with on the head conversion. Really not looking forward to that part.

[rcoville]

My 83 GS 1100 ES came without one when I bought it and I have never thought anything of it. I have a 4 -in - i header, yosh exhaust and K&N air filter. Since I bought it, I have put just over 10 k kms on the bike. Never had any hesitation and it runs beautifully.

BUT after reading all the other replies here, I may cobble up a make-shift cover this weekend and run the bike with it for a week to see if I notice any difference. I'll report back if I see anything from it of importance.

Well here's the results after running the bike with the made-up cover vs. no cover at all. The first thing I noticed was a slight hesitation in all gears when the revs were on the low side. This hesitation disappeared once the revs came up and the bike ran just as it always has ... strong with lots of power. The next day I removed the cover and set off on a 300 km road-trip. Absolutely no hesitation in any gear irrespective of the engine revs.

So for my bike at least, it definitely runs stronger without the air box cover.

This winter I may do the dynajet thing. I an toying with the idea of individual K&N filters and going 3rd stage.