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Richer needles?

  • Thread starter Thread starter Pendulum
  • Start date Start date
P

Pendulum

Guest
I've got mains dialed in, but my needles need to be richened up. I've got a '79 550 w/ the VM22 carbs.

What do I need to do in order to get my jet needles and needle jets "2 steps" richer? It'd be nice if these were number like pilots and mains : /

Stock specs are:

jet needle 5dl35-3 (the -3 3rd notch??)
needle jet 0-6
 
Put some small washers under the E clip to raise the needle about 2mm-3mm. If yours has notches just move the E clip down two notches.

:)
 
I thought shimming the needle only applied to the CV carbs. Thanks!
 
You don't say what mods you have. Your stock jet needle e-clip position is 3rd groove from the top.
If you have quality flowing pod filters and a quality pipe then you'd probably be best off placing the e-clips in the 5th (bottom) position and test. Always best to start rich and work your way back if necessary. It's possible that the stock needles won't work but you can try.
If 5th position is too rich then do what the plug colors and performance say to. If just slightly rich then you may need to install jetting spacers that allow you to make "1/2" position changes. jetting spacers are approx' .022" thick.
If the initial plug check at the 5th position resulted in very dark plugs then you may try position 4.
If your pods and pipe are quality then you'll need at LEAST 1 position richer, but more likely you'll need to go to position 4 1/2 as I described or position 5. If you do need to make 1/2 position changes (4 1/2) then place the e-clip in the bottom groove and place the jetting spacer directly on top the e-clip. This will give you position 4 1/2. Be sure to re-install any factory plastic spacers in their correct order too.
To accurately test how your jet needles are mixing, you need to test at 1/3 to 1/2 throttle position...no more and no less.
Keep in mind that every time you disturb the jet needles on your VM carbs you must carefully bench synch the carbs and the bench synch should be followed by a vacuum tool synch to best judge the performance when testing.
If you have any other intake/exhaust combo than what I described above you have to let us know as this will greatly effect the jetting.
 
Thanks Keith! I've got K&N pods and straight pipes. I'm planning to tune it slightly lean so that I can ride over to my buddys house and build an exhaust. It's beyond "slightly" lean right now. I've already got 2 mufflers, just don't have a welder at home. I figured if I tuned it slightly lean, that once the exhaust is on it'll probably be pretty close to perfect.

When I had my carbs apart for the rebuild it didn't look like there were notches on the needle, but I'll check again when I get my new pilot jets delivered.
 
OK. If I understand you correctly, you plan to jet it first, then make changes to the exhaust?? That's doing things backwards.
Since you're going through the trouble of making changes you want to re-jet correctly. Finish the exhaust first, then re-jet.
Now if your friend's house is a LONG way off and you're worried about running lean, then just place the jet needle e-clip 1 position/groove lower (down from the top) for the ride. It MAY still be lean but it won't be dangerously lean, that is if your jet needles are stock and not some butcher job a previous owner has installed. Your factory needles do have 5 grooves/positions. If not, then they're not factory needles.
 
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