Air Filters

[Tim]

Good evening 

New member here and I'm already looking for help.

Are all after market air filters the same as far as breathing goes, or is there a significant difference depending on brand and/or quality.

Now the question is out of the way I'll set the scene for those who are struggling to sleep.

I have a GSX400f which I'm slowly "restoring". I've put cone air filters on it which I picked up from Amazon for, admittedly, not a lot.

I have stripped and cleaned the carbs, pushing nylon bristles through the pilot jets to clear them. The exhaust is a very elderly N-eta 

Today I rode it on the road for the first time and it wasn't anywhere near as sprightly as the one I owned thirty odd years ago.

The poor thing runs very flat, hardly gets up a hill and whilst it revs fine on the driveway, as soon as there is any resistance like going up a hill, it can't do more than 40mph.  My thoughts are that it is cheap air filters but I wanted to iron the idea out before parting with quite a chunk for Ram Air foam pods.

All the best 

Tim

[Fazz711]

Hi bud. 

Welcome to OSS. 

Have you done any re jetting? 

Probably be better with original air box fitted if possible. 

[Swiss Toni]

Hello Tim. 

[wraith]

+1 with @Fazz711

yes there is a big difference between different air filters, if you want filters go for K&N reject the carbs to suit the air filters and zorst, that's is there is nothing wrong else where with the bike.

Some of the cheep air filters are cheep for a reason.

 

[banoffee]

Please tell me it at least has bigger main jets than stock? Just fitting (no matter how cheap and nasty) pod filters with no jetting changes will fuck things up.

[slayer61]

Isn't this about the time the bollocking starts about RTFR etc? And welcome to OSS!

[Tim]

Thank you, all

Yes ok the bollocking can start and will be dutifully accepted.

Umm I might not not have done any rejetting and I suppose I was in denial that it would need doing. Also I read that with K&Ns no rejetting was necessary, and hoped that would extend to any cone filter. The damage the web can do to the naive.

I will bow my head in shame and visit a professional.

The reason I don't have the original air filter is simply because the filter box is missing the lid and I can't find one for sale anywhere. I think I should keep looking for one.

Thank you for the common sense it is gratefully received.

[Gixer1460]

A K&N replacement filter for an OEM one won't need re-jetting - anything other than using the std. airbox will ! I don't know the bike but possibly the box lid is incorporated with the filter - new filter = new lid? Just guessing? Don't worry - professionals can be equally clueless if trying to relieve you of folding!

[Tim]

1 hour ago, Gixer1460 said:

A K&N replacement filter for an OEM one won't need re-jetting - anything other than using the std. airbox will ! I don't know the bike but possibly the box lid is incorporated with the filter - new filter = new lid? Just guessing? Don't worry - professionals can be equally clueless if trying to relieve you of folding!

Thank You,

You could have a point there, I have a very distant memory of someone saying something similar.

VERY distant.

Spoke to Fowlers, very obliging but didn't know so I've ordered a filter with an extra helping of hope.

K&N only make replacement oil filters for this one, a good call nonetheless.

Cheers 

[wraith]

The gsx400f was the 4 cylinder engine wasn't it? 

Don't always go just what model of bike for ordering filters (aftermarket) get the OD of the air intake side of the carbs and order pod or cone filters from there.

 

[Tim]

30 minutes ago, wraith said:

The gsx400f was the 4 cylinder engine wasn't it? 

Don't always go just what model of bike for ordering filters (aftermarket) get the OD of the air intake side of the carbs and order pod or cone filters from there.

 

That's right, four cylinder and not terribly popular.

Thanks for the advice. I did actually do that, feeling slightly pleased with myself.

But I just think I skimped where I shouldn't have done, like I say K&N don't make an air filter so I've gone original, may have to make my own air box cover if it doesn't come with one. Heaven knows how I'll do it though.

[banoffee]

Personally I’d start with a main jet at least 25% bigger, raise the needles if you can  then read the dynojet troubleshooting guide which is easily found on google etc.

Once running OKish get a dyno run / setup to get feedback / setup spot on.

May well never run as smoothly as with the air box though.. but it will least make a nice noise