I've had conflicting information reading about a drop in replacement K & N filter for the GS. Some say no rejetting some say to rejet. I wrote to K & N but even then the information was ambiguous. They say...

"On an unmodified motorcycle, the air flow restrictor must be installed in the air filter inlet."

Then they go on to say...

"If using a carburetor recalibration kit, the restrictor may be omitted."

Does that mean that using the air restrictor on an unmodifed GS will work but it's not an ideal solution? I don't really want to faff around with the carburettors, but I also don't want to put a K&N with restrictor on unmodified carburettors if it won't then operate normally.

Also why would a restrictor even be necessary, it's not like the air inlet is facing forward and it will have air rammed in. Won't the engine just suck in the air it needs? If the K&N filter passes air easier would that really make a difference? I mean it only passes what the engine tries to suck in.

Any enlightenment welcome.

The only benefit to using a K&N drop in filter w/ restrictor is that you'reable to clean the filter whenever it gets dirty. No jetting changes are needed with said restrictor. BUT.... it has been proven that K&N filters also allow more dirt into the intake, so that's the trade off. And something to think about: while a K&N can be cleaned and reused which might save some $$ in the long run, you'll have to buy the cleaning spray and re-oiling kit. And it takes about a full day for the filter to "dry out" to be used.

My opinion - if you aren't going to install a K&N and mess with the carbs, stick with an OEM type filter. But that's just my opinion.

My understanding is if the bikes exhaust is unmodified(no yoshi,etc) then the drop-in K & N is ok provided it's rubber restrictor is fitted(probably no restrictor is still ok)...........no rejet necessary.
As soon a u combine a highly less restrictive air filter(no restrictor) with a less restrictive exhaust then u lean out the mixture too much,hence a rejet necessary.
I would like to know myself if a K & N drop-in with restrictor fitted,combined with a Yoshi slip-on would require a rejet....i figure it probably wouldn't?

OK I was not aware that the K&N allowed more crap through, I thought it was the opposite. I was mainly interested due to their claiming that it need not be cleaned for 50,000 miles.

I've put a HiFlo filter in and when I have checked it at 3,000kms as per the recommended service interval, both times it has looked pretty clean and blowing compressed air through it did nothing. So I was wondering if checking it at 3,000 is really necessary or even if replacing it with another $40 filter at 12,000kms is necessary if it still seems clean. Or do they get clogged up with micro particles that cannot be seen? Should I just keep running the standard filter unchanged as long as I don't notice a performance drop.

Quote from: Big Rich on February 10, 2016, 12:11:15 AM
The only benefit to using a K&N drop in filter w/ restrictor is that you'reable to clean the filter whenever it gets dirty. No jetting changes are needed with said restrictor. BUT.... it has been proven that K&N filters also allow more dirt into the intake, so that's the trade off. And something to think about: while a K&N can be cleaned and reused which might save some $$ in the long run, you'll have to buy the cleaning spray and re-oiling kit. And it takes about a full day for the filter to "dry out" to be used.

My opinion - if you aren't going to install a K&N and mess with the carbs, stick with an OEM type filter. But that's just my opinion.

That I can't tell you.... I run K&N on everything and rejet. But search around a little bit..... I think Buddha uses gasoline to rinse the OEM filter at the first "change" interval, and actually gets a new filter at the second interval.

Quote from: user11235813 on February 10, 2016, 01:36:03 AM
OK I was not aware that the K&N allowed more crap through, I thought it was the opposite. I was mainly interested due to their claiming that it need not be cleaned for 50,000 miles.

Believe it, having said that, thousands of users have gotten millions billions of miles out of them.