Help with cruising surge

[Sweetwilliebrownjr]

Alright muscle jet kit, 157.5 mains, needle at 1 1/2 clip from blunt end, stage 7 springs, slides not drilled. Runs great everywhere but off idle, cruising speeds. I'm nearly positive main jet is right, as I tried 2 above, and one below. It pulls the hardest. The needle position may be off 1/2 clip, but its damn close. I have 177.5 paj installed, and there's no difference with it or the stock one. I cannot find any vacuum leaks. The vboost is still set as stock. If I cover half the air filter, or choke it, it runs great at cruising speeds. It's a severe surge at times, and from the sound of the exhaust, it's almost like its dropping a cylinder or 2 when it does it. The floats are set at almost exactly 17mm wet. I need some direction here. I'm thinking maybe the floats need raised?

 

[Suave Cowboy]

Bump!

 

[maleko89]

Try turning out your mixture screws a 1/4-1/2 turn. If that doesn't work, then raise needles a 1/4 clip.

 

[Sweetwilliebrownjr]

I've tried turning the mixture screws out in 1/2 increments to about 2 turns past where the idle drop put them, no difference. So, is richening the needles gonna help all that much at a steady cruise? On the third clip, everything else the same, it ran good at a cruise, but was cutting out a bit 5-7k or so at wot. I dropped to 2nd clip, cruise went to crap, but 5-7 k was better. 1.5 clip pulls like crazy 5-7k. So, I guess I'm gonna have to sacrifice the upper rpm to be able to have a steady cruise?

 

[[email protected]]

Sounds like the needle is a touch lean. I had a similar issue and raising it half a clip did the trick. If you are running stg7 needles, I would think your mains are a bit rich with 157.5's.

 

[Sweetwilliebrownjr]

Well, I'm not sure about the stage 7 needles. They're whatever come with the muscle jet kit. With the engine fully warmed, I've tried above and below 157.5. The 160's were obviously rich, and the 155's pulled way softer than the 157.5's. if I go up or down, I'm losing power without a doubt. I'm still gonna try 1/2 clip richer, but seeing how a whole clip richer made no difference, I'm thinking that's a no go as far as a solution. A whole clip richer made it bog around 6.5-7k. That issue is gone with the needles where they are. I'm thinking it is a 1/2 clip lean though.

 

[maleko89]

It pulled hard in what rpm range. For main jets, test from 7500-9500 at WOT. Then, tune the needles. Are floats set to the same setting?

 

[Sweetwilliebrownjr]

Pulled hard on main jet 7.5k up. Pulled hard on needles in 5-7.5, though, I'm still gonna try 1/2 clip richer, because I jumped from 2.5 clip to 1.5 clip. All floats at exactly 17mm wet. That's all wide open throttle. I'm using vmax outlaw tuning guide.

 

[KONG W]

I'm having an issue that is similar. I have a 1/8"-1/4" throttle lean feeling and the right side exhaust feels like it's sputtering. RPM 3900 -5000. It runs great everywhere else.
I have muscle jet kit, needle on 4th clip from blunt, 155 mains, 177.5 PA2. I moved the needle to the 5th clip and had a dead spot then a power surge hitting WOT around 3k. I had lots of popping on the 3rd clip. I tried taking my carbs off and roundhousing them but no luck. I will try the beating my wife next.

 

[Sweetwilliebrownjr]

Well, to update, I found a leak in 2 of the v boost manifold joints. Spraying them was doing nothing, so I used our smoke machine from work, and found them pretty easily and fixed em. This didn't stop the surging or off idle problems. I had to go another half clip rich on the needle, and ended up with the mixture screws about 4.5 turns out. The 177.5 paj2's are still in there. I've got new joints coming, and will start over with testing all needle clip positions when I've got em on. I'll prolly give the 155 main jet another to as well, just to see if the leaks were "helping" the 157.5. I should have used the smoke tester first. I sprayed this damn thing down a good 10 times thinking there was a leak, but it never showed up.

 

[one2dmax]

I need to get me one of them thar testers! If you have that much a/f screw you may need to go richer on the needle. If you have a lot of needle you may need to go richer on the mains. The 177.5 PAJ 2 will lean up the entire range with heavy emphasis on the midrange.

 

[Sweetwilliebrownjr]

I'm 2.5 clip right now, and its still got a lean surge cruising at anything under 3k. But it's slight. I'll "start over" on everything when I gets my new vboost boots. The 177.5 paj prolly explains why the midrange was never just right. I thought the paj richened it up. i guess I've confused myself from reading too much. As far as the main, that jokers strong in the way upper rpms. We'll see how she does when ive got everything sealed off. I need efi! Soooooo much less time consuming and confusing.

Smoke pro tech-mate is the smoke tester we have. Works wonders on emission systems, vacuum leaks, air leaks in weatherstripping, exhaust leaks. The uses are endless. I prolly break it out at least twice a day at work. It uses baby oil to make the smoke, which stinks horribly when vaporized.

 

[jwood]

Ok.. Here we go... UFO QUADZILLA'S, stage 7 with pods, 165 main, 4th clip on the needle, just fixed my surging issue! Instead of the recommended 2.5 turns out on the A/F I am setting on 1.5 out, smooth through the full the whole throttle range... No more surging...

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