Jet Needles

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The needles arrived!

I have dinner plans tonight and it's going to be chilly all weekend here (in the 50's) so I'm not sure how much testing I can do with it. I might be able to get the stumble out but I'm going to hold off until next week (back in the 70's) to do the plug chops and main jet adjustment.
 
HAHA! I played with it before dinner and I was able to get that pesky stumble out of it. I then swung the pilot jet way out the other way. It was good and happy at 48 with the extra fuel at the idle. Now the idle is hanging. I may try to balance the needle diameter with the pilot jet to get it happy, I still have to play to figure it out.
 
Oh Bob, .01mm is a big difference in needle diameter. It's a noticable step decrease in sputtering with just the one up size .01mm larger needle. I ended up with the JFL needle in the 2nd clip position ( although the 3rd might be the happy medium between having a rediculously large pilot jet and having the idle completely seperated from the 1/4 throttle mixture) I'm also looking into two even leaner needles so I can tune it come summer time.
 
I've already contacted jetsrus about a pile more jets and two bigger needles. I'm going to work with it until I crack this nut. Needles and jets aren't expensive, heck I think I've poured more gas out of the float bowl fiddling with pilot jets than I spent on needles...
 
Well you know, the tuning principles are exactly the same on all needle venturi carbs. The numbers are different but the idea's the same.

I knew I couldn't be the only one wondering how much difference needle diameter made to tuning and I couldn't really find any info on it so now I know!

Bob, I'll be getting a few more needles in in a week or two and trying to work with those to see how much more they affect it. Once I settle one the needle that works best for me, I'll package up the pile and ship them to you. You play with yours to try and dial out the stumble and ship the pile back. How about that for a BF hookup?
 
Well you know, the tuning principles are exactly the same on all needle venturi carbs. The numbers are different but the idea's the same.

I knew I couldn't be the only one wondering how much difference needle diameter made to tuning and I couldn't really find any info on it so now I know!

Bob, I'll be getting a few more needles in in a week or two and trying to work with those to see how much more they affect it. Once I settle one the needle that works best for me, I'll package up the pile and ship them to you. You play with yours to try and dial out the stumble and ship the pile back. How about that for a BF hookup?


I just told the blasty what your gonna do, and it sported a woody! That would be awesome! I really hope i can get this mother running right. Later next week I'm gonna put the modded start wheel in and rip the carb apart again, completely disassemble it, clean it again for the fourth time, check the float level, Now that i just figured out how to do this, and step down another pilot, I'd like to get the air screw to 1.5 even 1.75 would be ok with me, that would give me a better swing of adjustment when the frigid weather gets here. I don't plan on riding it too much in the winter but if we get a snow like last year and that's my only way of getting around , then for sure. Thanks for the hook up! -Bob
 
Well don't play with that pilot too much until you have a thicker needle to throw in there, the needle diameter affects the idle area too. If yours reacts to the needles like mine did, you'll find that as you cut down on the sputtering, you'll need to bump up the pilot some to compensate for the fuel that was leaking past the needle at idle. I'm .02mm larger on the needle and 4 numbers larger on the pilot jet. I still have more needle thickness to go before I find my happy medium. The sputtering and splooge have gottn better. I now have about 8 splooge spots on my floor, splooge running down the front of the motor, splooge on the frame... you get the idea. If yours isn't that bad Bob, one of the needles I already have might fix your problem.
 
Ok, I finally got something on the needles... I got one of the three new needles to finally get on the other side of rich. I have the second of the bunch out on the lean side surging even when I move the clip down to pull the needle up. I'm going to start balancing the pilot jet with a needle one step back from that one to get the idle in without sputtering when I take off.

I'm really on top of the jetting now.

slicker, PM sent!
 
AHHHHH! this carburetor is driving me nuts <---- which is what you say right before you go back to the instruction manual and read it cover to cover again.

I finally got the sputter out with the needle but couldn't get the idle to stop hanging. I finally broke down and pulled it off to check it all out and noticed where I had the idle adjusted to the slide was completely closed. Now how in the hell does an engine run with the slide completely closed unless.....

Time for a leakdown test. A month ago the engine held 6 psi overnight. I fiddled with a few things and BAM all of the sudden this thing is a sieve...

The intake manifold was leaking where it was clamped to the carb, at the gasket between the mani and the reeds, and somewhere else (not determined yet).

I lost 4 psi in about 45 seconds and then the loss leveled off SOME. I just sat back and shook my head. I'm working on the intake parts tomorrow and I have a separate leak I have to find once I can get the engine to hold enough air to move around to the other side with the soap solution.

Lesson learned, leak check EVERY TIME anything is touched!

Slick, can the needles wait for a turn? Once I get the engine to hold air again I'll need to work on the jetting again. UGH.
 
Of course, they can wait.... Air leaks suck! If I could get my power pros exhaust to not leak, doing a leakdown test would be simple, but I have to remove the stupid exhaust scrape all of the RTV off and then reapply it, very annoying but it is better than blowin sh*t up. I did have the exhaust air tight one time and was able to put a cover on the end of the pipe but that was only once. I hate Vforce reed cages, next time I get 150 bucks I'm going back to the rad valve.
 
Of course, they can wait.... Air leaks suck! If I could get my power pros exhaust to not leak, doing a leakdown test would be simple, but I have to remove the stupid exhaust scrape all of the RTV off and then reapply it, very annoying but it is better than blowin sh*t up. I did have the exhaust air tight one time and was able to put a cover on the end of the pipe but that was only once. I hate Vforce reed cages, next time I get 150 bucks I'm going back to the rad valve.

RAD valve FTW!!!!! sorry slick no take backs!! lol :D :D :D
 
The new style valves, use a rubber connector you don't use your intake boot. The older style like scoobs has you can use the stock Intake boot (manifold). I've been scouring around to find one but there are no used ones out there. Plus the pedals are so much cheaper than the vforces.
 
I've seen the one with the rubber connector on it but I'm wondering what size the aluminum is inside that rubber connector. If the hole in the inlet side of the rad valve is only 30mm then it doesn't make any sense to have one with a larger carb than that.
I was just wondering.

Tonight I have to deep fry a turkey for my wife to carry to work so I might not get but a few minutes of leak checking in tonight... ugh
 
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