Hello. I have a GS500 with 98 stock exhaust and air filter. I bought a UNIFilter foam but I have problems to rejet. Too much air flow, I increased the main jet to 150 (previously 122.5) but still lacking. The only solution was to partially cover the entrance to the filter. Someone had the same problem when using the UNIFilter?
(I apologize for my English which is very basics)

I think you are trying waaayyy too large main jet. 150 main should be used with K&N Lunchbox and free flowing exhaust. try this post for correct setup: http://gstwins.com/gsboard/index.php?topic=35237.0

good luck and don't worry about your English - it's perfectly understandable!

Thanks kml.krk
I read this post and I tried main jets sizes 130, 140 and 150. And it still fails in middle rpm, even with the needle in the highest position. And the fault disappears if cover partially the filter

From what I've read on here it is difficult to re-jet with a filter with the stock exhaust. Too much air going in with the stock restrictive exhaust. That's why when you partially cover (restrict) the intake it runs correctly.

Quote from: boxin on May 11, 2009, 11:01:53 AM
Thanks kml.krk
I read this post and I tried main jets sizes 130, 140 and 150. And it still fails in middle rpm, even with the needle in the highest position. And the fault disappears if cover partially the filter

What exactly are you running.
Uni in the air box and stock pipe ... and maybe failing in the mid range is because its too rich.
If you open the throttle and the bike makes soggy power and feels like its trying to get out from under water, that = rich.
Uni in the air box, and stock pipe needs 125 mians and 1 washer ... whoooo ... you said needle in the highest position - you ahve DJ in it, then forget it, no jet changes will work, call DJ for help. Stock needle is 1 position only.
Cool.
Buddha.

Buddha: I do not understand well that the "soggy power" and "under water", but i think that is what happens if I am not mistaken.
My needle is the original (stock), I dont have DJ kit, in my country has entered the needle 5-position.

I have a UNI filter + stock exhaust with 125 mains , 40 pilot and 3 turns out on mixture screws runs good , maybe a little rich

but no major problems.

Overly rich condition is like this: You open throttle and bike goes brrr brrr brrr     and then  accelerates strongly

So I think it is not my case, when open throttle 3 / 4 the bike does nothing. If open full accelerates like a rocket. If I cover the filter that does not happen and the bike accelerates smoothly.
Note: This exhaust was open because there was something loose inside it making noise, that thing took off and no longer has the same retention gases.

Affschnozel, Buddha: Do you mean that the bike bucks when there's too rich?

Quote from: boxin on May 11, 2009, 06:45:42 PM
Note: This exhaust was open because there was something loose inside it making noise, that thing took off and no longer has the same retention gases.

I'm explaining this in other words to try and make myself understood.
The exhaust was open because there was something loose inside it making noise, I took the exhaust to a garage because it rattled and they took off the damper, perhaps?? (do you call it like that?) and it no longer has the same retention of gases or fumes"

so you are saying that your stock exaust has been cored, as in the baffles have been removed?

You are sounding lean (cover the filter and it works fine = lean).
Let me read your posts again.
Cool.
Buddha.

Anyway , you can always look at your spark plugs to determine if lean or rich

Quote from: natedawg120 on May 12, 2009, 05:56:38 AM
so you are saying that your stock exaust has been cored, as in the baffles have been removed?

Exactly.
Spark color is ok.

So? If I raise the float level? What do you think?