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Annoying bogging problem on 550 after air filter replacement

  • Thread starter Thread starter onchiman
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onchiman

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Well I just spent the afternoon trying to figure out what to do about a bogging problem I got after installing a new K&N filter ($$). The bike is a 79 GS 500E. It's stock except for Dyna S electronic ignition and new coils and plug wires. The air box is stock and I bought a K&N filter thinking it would improve my gas milage a bit. Well, instead after I installed it, I now have a flat spot, bogging,starving at 3/4 throttle. It's most noticible in higher gears like 5 and 6. Pulls great until then. I moved the needle clips down one groove but it didn't make any difference. It's got the stock mains in it. Can anyone suggest what size jets might work with this filter setup? When I put the stock filter back in it runs great. Sucks because the K&N was expensive! If I go with bigger mains and the K&N will my fuel economy suffer? Please help. Thanks

Onchiman
 
gs500 or gs550? IIRC there was no gs500 in 1979.

Also, what kind of K&N are we talking, are you putting on the K&N pods? or is it a filter in the airbox like the stock setup?
 
Oops my bad, she is a GS 550E. It's just the K&N replacement filter with the stock airbox. I got it because according to what I read, it wouldn't need rejetting. So much for that! The carbs are VM with the standard #80 mains. Exhaust is stock 4 into 2.
 
Well you probally won't need to replace the mains. Since your problem is in the midrange, I"d reccomend raising the needles a notch. That should take care of the problem nicely.
 
Well I raised the needle a notch yesterday. You mean another notch? There is only one more notch left towards the bottom of the needle (in other words the needle clip is on the second groove from the bottom). Think that will do it? Also the bike pulls pretty good except for that final 25% of throttle when it hits the wall.
 
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WELL, then ti's time to reset back to stock, and start tuning properly. Set it back to the factory settings, and see just how lean you are up top. My first guess is you'll need to goto 85's. If I had jets that size I'd send them to you. However I don't :-/ you'll be paying $9-12 per set of jets.
 
Have you oiled the filter yet? It should have a light dose of filter oil - K&N oil is usually red. The cotton has no real resistance and no real filtering effect until the air is forced to travel through the oil in the weave.

Kim
 
Yes, the filter is oiled. It came from the factory "pre-oiled". Should I oil it some more perhaps? Maybe with some Molasses? I've checked for intake leaks and none were found. Plug color after trying high speed run seems tan to gray.
 
Then yes, you'er running a little lean.

Don't re-oil the filter yet. The filters come oiled from K&N.
 
Okay then I'll reset the needles to stock position and try some 85's. Bummer as I was convinced by the K&N web-site that no fiddling around with jetting and such would be necessary. Thanks for the help.
 
onchiman said:
Well I just spent the afternoon trying to figure out what to do about a bogging problem I got after installing a new K&N filter ($$). The bike is a 79 GS 500E. It's stock except for Dyna S electronic ignition and new coils and plug wires. The air box is stock and I bought a K&N filter thinking it would improve my gas milage a bit. Well, instead after I installed it, I now have a flat spot, bogging,starving at 3/4 throttle. It's most noticible in higher gears like 5 and 6. Pulls great until then. I moved the needle clips down one groove but it didn't make any difference. It's got the stock mains in it. Can anyone suggest what size jets might work with this filter setup? When I put the stock filter back in it runs great. Sucks because the K&N was expensive! If I go with bigger mains and the K&N will my fuel economy suffer? Please help. Thanks

Onchiman
Click to expand...

I would contact K&N and see if you can return the filter for a refund. I would then put the stock filter back on. The stock filter will do a a better job of filtering the air, which is the primary job of an air filter. Then instead of fiddling with the carbs to try to make the K&N work, you can go riding.:)
 
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