johnsnownw Posted March 31, 2011 Posted March 31, 2011 So, I finally decided to add Uni-Pod filters and re-jet. I'm using these filters: Now the plan is to re-jet going 2 up on main, 2 washers to raise the needle, and 1 up on the pilot. Anyone think this isn't the way to go? I've been debating on going 2 up on the pilot as well, but I think that might be too much. I've decided to start out as 2 up on the Main as that's what they suggest doing with BS34 carbs on the 650's, here: http://www.amckayltd.com/carbguide.pdf Let me know what you all think.
Moderator Airhead Posted March 31, 2011 Moderator Posted March 31, 2011 Anybodys guess, carburation it's a bloody nightmare when you start messing with it
Moderator drewpy Posted March 31, 2011 Moderator Posted March 31, 2011 just change 1 thing at a time, or you will be going roung in circles
Paulwhite Posted April 1, 2011 Posted April 1, 2011 id do your pilot jet 1st as thats the most important, then start it up and do some checks, then the needle, (start up and check again) then the main if its running lean on top.
Preload Posted April 1, 2011 Posted April 1, 2011 Pod filters with a capped off end can cause air flow problems (well on 2 stroke motors they do) there maybe a air corrector kit available which will save you a lot of trouble.
johnsnownw Posted April 1, 2011 Author Posted April 1, 2011 Thanks for the suggestions all! Preload, I hadn't heard that...I'll make sure to watch for it.
Moderator Cynic Posted April 1, 2011 Moderator Posted April 1, 2011 Thanks for the suggestions all! Preload, I hadn't heard that...I'll make sure to watch for it. You get the same effect as the pressure wave that returns in the expansion chamber and keeps the charge in the cylinder, same thing happens in the filter, trouble is the metal top causes the wave to comeback at the wrong time and restrict the incoming air. If you must have pods you want to try and get full foam jobbies.
Moderator drewpy Posted April 1, 2011 Moderator Posted April 1, 2011 You get the same effect as the pressure wave that returns in the expansion chamber and keeps the charge in the cylinder, same thing happens in the filter, trouble is the metal top causes the wave to comeback at the wrong time and restrict the incoming air. If you must have pods you want to try and get full foam jobbies. or put them on the end of a tube to minimise the effect. the main problem I think is you have CV carbs, it upsets the diaphram movement (prob the pressure wave you mentioned)
johnsnownw Posted April 1, 2011 Author Posted April 1, 2011 You get the same effect as the pressure wave that returns in the expansion chamber and keeps the charge in the cylinder, same thing happens in the filter, trouble is the metal top causes the wave to comeback at the wrong time and restrict the incoming air. If you must have pods you want to try and get full foam jobbies. So, is this one of those, it CAN happen, or it WILL happen deals?
johnsnownw Posted April 1, 2011 Author Posted April 1, 2011 Well, I decided to order these due to the end cap issue: I guess I'll probably send the others back, they aren't exactly cheap.
xv535 Posted April 2, 2011 Posted April 2, 2011 Hey John I like the red Uni's...if they don't work use them as targets for the 357 or send them to me and I'll see if they work on the 44 mag . Rocky
Moderator Cynic Posted April 2, 2011 Moderator Posted April 2, 2011 So, is this one of those, it CAN happen, or it WILL happen deals? I have told this story several times now. Tuning shop in Towcester near me called TTS (used by many national magazines and people like Jack Frost etc)I expected pods of some sort when i had quite an aggressive tune done, they will fit pods for 2 reasons only. Tuning for the drag strip, or a direct customer request. Unless your running all or mostly WOT they do not have enough benefits over a good filter in a regular airbox to be worthwhile. Of course, asthetics is entirely different
johnsnownw Posted April 2, 2011 Author Posted April 2, 2011 I have told this story several times now. Tuning shop in Towcester near me called TTS (used by many national magazines and people like Jack Frost etc)I expected pods of some sort when i had quite an aggressive tune done, they will fit pods for 2 reasons only. Tuning for the drag strip, or a direct customer request. Unless your running all or mostly WOT they do not have enough benefits over a good filter in a regular airbox to be worthwhile. Of course, asthetics is entirely different Where were you when I was buying these filters? It's very inconsiderate of you, Cynic. I decided to go pods because I wanted increased air flow so I could up the jets. My 400 has always seemed to run lean unless I turn the mixture screws way way out. Also, I'm tired of dealing with the stock set up when I want to do anything with the carbs...it's just a pain. I guess the second reason is that I'm lazy. Hey John I like the red Uni's...if they don't work use them as targets for the 357 or send them to me and I'll see if they work on the 44 mag . Rocky If I were going to destroy them, I think I'd do it myself. Then again, I wouldn't mind seeing what a 44 mag would do to them...hmmm
Preload Posted April 2, 2011 Posted April 2, 2011 My 400 has always seemed to run lean unless I turn the mixture screws way way out. Are you sure that turning the screw out richens the mixture but I thought turning the screw in richened the mix? I havnt worked on a XS400 for over 20+ years so don't take this as gospel. Also the air screw only effects the first 20-25% of rev range so doesnt effect much above that.
johnsnownw Posted April 3, 2011 Author Posted April 3, 2011 Are you sure that turning the screw out richens the mixture but I thought turning the screw in richened the mix? I havnt worked on a XS400 for over 20+ years so don't take this as gospel. Also the air screw only effects the first 20-25% of rev range so doesnt effect much above that. Yup!
johnsnownw Posted April 8, 2011 Author Posted April 8, 2011 Alright, well here's how the re-jetting went. I went one up on the main, and left everything else as-is, and the bike runs pretty well. The only issue I have is that every once in a while it will backfire through the carbs. Not really enough to be a concern, but I had to turn the mixture screws out about 5.5 turns. I did try to go one up on the pilot, but it was running like crap. If I'm not mistaken backfiring through the carbs mean the mixture is just a tad lean. Does anyone think going 1 down on the air jet would help? Actually, I'm a little confused about the starter jet and air jet after looking at my Haynes manual. Thanks again guys.
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