Modifying stock air filters

Use the valuable search function as this topic has been discussed a lot but just to abbreviate "most any filter foam will work". It seems they mostly use lawn mower filter foam though. Have you thought about doing pods if obtainable. Then again you will most likely need to rejet and I don't know how obtainable jets are for these carbs in your location.
 
You can get new foam to refoam them thats what I did with mine.I know alot of people will use after market pod filters which suck in more air so you have to rejet to compensate.With that being said I dont realy see any advantage of running them.Engineers design the filters to work as they should on our bikes.Others may have a different opinion on this but unless somebody can prove to me that there are significant performance gains running them Im using my stock filters.
 
Hi, sorry couldn't find the exactly same topic. Thank you for your advice. What exactly do you mean by "rejet"? I understand, I'll have to get some different jets?
 
You have to rejet your mains to compensate for the extra airflow from using pod filters.Then you have to upgrade the pilots usaly 1 size up depending on what size they are.Me personaly I like the stock air filters and I dont ever plan on going to pods.
 
1982400xs said:
You can get new foam to refoam them thats what I did with mine.I know alot of people will use after market pod filters which suck in more air so you have to rejet to compensate.With that being said I dont realy see any advantage of running them.Engineers design the filters to work as they should on our bikes.Others may have a different opinion on this but unless somebody can prove to me that there are significant performance gains running them Im using my stock filters.
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Well, when you supply more air and the fuel to match, you get better/bigger combustion meaning more power. It's been like that since internal combustion engines were invented. Of course "significant" is subjective, but if you can get a few HP by changing to pods and rejetting (costing a total of $50, maybe), why not?

BTW, engineers design for the masses and to meet financial thresholds or environmental thresholds. So the Yamaha engineers designed with that in mind, not more hp, with higher emissions and lower MPG.
 
Charles said:
Well, when you supply more air and the fuel to match, you get better/bigger combustion meaning more power. It's been like that since internal combustion engines were invented. Of course "significant" is subjective, but if you can get a few HP by changing to pods and rejetting (costing a total of $50, maybe), why not?

BTW, engineers design for the masses and to meet financial thresholds or environmental thresholds. So the Yamaha engineers designed with that in mind, not more hp, with higher emissions and lower MPG.
Click to expand...

I don't need extra power, I just don't want to spend money on stock filters that are extremely costly where i live. so assuming my custom filters supply more air than stock ones, do I need to supply more fuel? If so than how? Or can I leave it as it is with just more air and and stock fuel?
 
@amkxxx I was just suggesting that you get pods anyways since you are already spending money on filters but I understand you want to re-foam the stock filters so you can save money and so you don't have to "supply more fuel" through the jetting process (previously explained by Charles). If you were to just to slap on pod filters (without jetting) you would create a lean state (too much air not enough fuel) causing the engine to overheat which will have negative effects.
 
1982400xs said:
Thanks charles so how much horsepower is gained approximately?
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What, 2-3 hp at most? But hey, if you need new filters, why not? rejetting isn't that hard, nor expensive. I'm not 100% convinced you always have to rejet with just pods.

amkxxx said:
I don't need extra power, I just don't want to spend money on stock filters that are extremely costly where i live. so assuming my custom filters supply more air than stock ones, do I need to supply more fuel? If so than how? Or can I leave it as it is with just more air and and stock fuel?
Click to expand...

Add more fuel by rejetting your carb. But like I said, you might not even have to. Changing to pods and riding to test how it feels isn't going to blow up your engine. Get them, run them, see how your bike feels/revs/runs, then check your sparkplugs to make sure they look OK.
 
Need the extra power becuse I am a power/speed freak..If I riding along doing 65mph and some slow asz is in my way I want the power to pass them and not have them pass me back LOL
 
Charles said:
What, 2-3 hp at most? But hey, if you need new filters, why not? rejetting isn't that hard, nor expensive. I'm not 100% convinced you always have to rejet with just pods.
Click to expand...

It depends on the bike; my friend's old Honda CB360 didn't need jetting for pods; the carbs on that bike are amazing, however. It ran fine with no air filters at all while we were testing. The plugs looked great.

The XS400, on the other hand, is much more sensitive to intake changes. I think pods even have a more pronounced impact than most new mufflers will.

I am not saying skipping the jets will necessarily cause you to run so lean that you experience detonation, but you definitely won't be running well and will probably experience a lot of popping and backfiring.
 
I'm actually about to check the jetting on my carbs cause I have pods and straight pipes. I could swear that when I cleaned up my carbs I was running stock jet sizes. So I'll let you know what I find.
 
My bike was popping and back fring for a while,I wasnt sure why.I had check everywhere for vacume leaks and even thought it was my exaust that was causing it.After looking at the material I used to refoam my air filters It looked like it wasnt dense enough foam and it was sucking alot of air.I have since found a better material to refoam them with but havent had a chance to run my bike to see if theres any difference.I have also rejetted my carbs so I cant wait till a can see if there will be any differences.
 
Hi guys I'm back.

I changed air filters to pods and now my bike has some issues.
It can't stay on low rpm for long. It gets to the high rpm fine but just after getting back below 3000 rpm it goes down and then after a few seconds stops. It's on warm engine.

The second problem is that even though it reaches high rpm nice when standing on neutral when I ride and apply too much throttle it starts to choke. I changed main jest from 128 to 140 and now it's a little better but the problem still occurs.

Do you think my problems would be solved by changing pilot jest to bigger?
Or maybe it's something else?
 
Look at your spark plugs, they will tell you where you are at with jetting...128 to 140 is a big jump. I just went up one size when I switched to pods...My exhaust is unchanged.
 
my spark plugs look fine. but i still get choking and engine stops when idle. My exhausts are untouched too. I tried switching back to the original air filters and i was surprised to find that now choking is much worse, I can barely ride.
My floating level is set to 1mm below chamber, I cleaned the carbs, membranes are fine, im getting fuel. What could be wrong?
 

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