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Made airbox lid...bike bogs down

  • Thread starter Thread starter eastern
  • Start date Start date
E

eastern

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I am new here and wanted to thank everyone for the info they have contributed to these boards. I would not be riding my GS without this forum. I purchased my first motorcycle...1980 GS550L...around 4 months ago and have since completely rebuilt the carbs, rewired the r/r situation, and fixed the rear brake today. I made a manometer and was going to sync my carbs today but felt it would be better off to seal the airbox completely like many have mentioned as I felt the bike was running lean and this could be a contributing factor. So I made an airbox lid out of sheetmetal and 3/4 rubber foam weatherstripping and even painted it glossy black to match the frame. Anyways...I tightened the screws down on the lid and went to start her and barely a sputter. So I put the choke on about 1/4 of the way and then really nothing happened. Hmmm...so I removed one of the screws to the airbox lid and slid it over so that half of it was covered. Guess what? She started right up and as soon as I moved the lid back over she started started bogging down and some white smoke started coming out the exhaust. I am thinking that possibly the airfilter has too much oil and that is why she is starting to smoke some. My main question is I thought it would be better off to have the airbox sealed to prevent the lean condition prior to synching my carbs...and basically the better sealed the better off you are. Am I wrong? I did take her out for a spin with the lid about 1/3 of the way off and she ran better than she ever had before...seemed like she pulled a lot harder than before and the popping on decelleration was a lot less and almost barely noticeable. Any suggestions on what I should do to be able to properly have the airbox lid on and not have the bike bog down at all?

Thanks,
Ryan
 
"but felt it would be better off to seal the airbox completely like many have mentioned as I felt the bike was running lean and this could be a contributing factor."

What you want ideally is to ensure that no unfiltered air gets into your carbs. By the airbox, are you referring to the filter housing perhaps? You want good airflow to your filter outer surface otherwise you're choking the engine.
 
The stock lid may have had a hole ???? Stock filter is NON oiled paper type
 
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On my '79 GS550 the lid is under the seat and does indeed have an opening. It's roughly "Quonset hut" shaped and with a baffle of some sort. It sticks up from the top if the airbox about an inch.
 
The airfilter I have is stock. At least that is what is shown on the parts diagrams. It has the metal housing with the foam wrapped around the side that does not come in contact with the side that seals to the airfilter box. I don't think there could be a paper type filter as there is a metal basket inside.

I think I am need to be slapped (I am sure my girlfriend would be happy to give me a hand in that dept)...or maybe I have been out in the sun too long without any rain. Rethinking the situation it is obvious NOW that the airbox cannot be fully sealed to not let any air in like I did or else there is clearly not enough air being supplied. Nice huh.

The next steps I think I am going to take will be to get out as much excess oil out of the foam element as possible. I think I have too much. Just enough so that there are no dry spots I guess. Then I am going to start drilling holes (with the lid off the box) one by one to see when I get the best results and go from there. I must be on the right path with this somewhere though as when the lid was off 1/3 of the way it ran better than ever.
 
Examine the airbox carefully. There's no way that the OEM airbox cover will completely choke the inlet. (It ran when new, right?)

Most bikes have an intake snorkel (a flat rubbery tube) that pulls in air from beneath the seat or around the front of the rear fender.

For folks whose bikes need an 'awakening agent' like ether, it's good to know where this snorkel lives.

Anyway, it's bound to be there somewhere. Not to say that modification of the airbox would help or hurt.
 
Hey Robert. Thanks for the orings! When I got the bike it did not have the airbox lid. I just made one out of sheetmetal and weatherstripping. Onchiman said that their OEM lid had an opening of some sort which my "homemade" lid does not. I think that is the problem. It is not getting enough air into the box at all.
 
Odd...

Odd...

This is just weird. Here's what BikeBandit shows for that bike:

airbox.gif


What is this??
 
That's it, the top-most item in the picture above. Although you can't see it in the drawing it's open towards the back.
 
The stock filter cover has a hole about 1/2" tall and 3" across. The hole
is covered over by a half shell with the opening pointing backwards. I'll have a picture for you tonight with precise measurements.
 
The stock airbox has a hole in its lid. A completely sealed airbox will not flow air and your bike will not run. Mine has a roughly 2 1/2 inch hole in it. with a snorkel, you should have a hole in your cover with some kind of snorkel to prevent rain from getting in the box
 
A lot of people ditched the airbox lids, because they found they got a significant horsepower increase without them.
 
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