Pod filters mounted, havent jetted yet

engine22 · Full Member Joined: Apr 10, 2008 Posts: 104

so i put my mikesxs pod filters on today, I'm waiting on some larger jets in the mail.. I tried going up and down the block with them and the bike seems to idle fine, but I have absolutely no power and it is not running at all like it should.. Is this due to an excessively lean fuel mixture because the new air filters? Is it something else?

Also, at the moment, breather hoses are just vented to atmosphere..

5twins · Full Member Joined: Aug 05, 2006 Posts: 1616

'78 carbs? Are you sure? The reason I ask is carb swaps are common on these bikes and carb jetting specs changed over the years almost every year or 2. You must base your re-jetting on the carb set year, not the bike year. That being said, re-jetting for one mod like filters shouldn't be that extreme. Maybe one size up on the mains. Try 2 eventually to rule it out. One of the first rules of jetting is that when you think you're right, try the size above and below to make sure.

Larger mains may cause break-up in the upper midrange under heavy throttle applications. If that happens, you'll need to lower (lean) the needle setting. When you do that, it also leans the upper part of the idle or pilot circuit and a larger pilot jet may be needed as well.

Leaning the needle setting has it's drawbacks. While necessary to cure the upper midrange richness and stumbling caused by larger mains, it also leans the rest of the midrange, making it rather flat and unresponsive. It's best to lower the needle the least amount possible, just enough to cure those stumbles. Many of us shim the needle setting to get a position less than moving it a full clip notch.

Here's a thread with ideas for those breather hoses .....

xs650temp.proboards29....635&page=1

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