thanks for the info. I sent him a pm and we'll see what he has to say. meanwhile ill have fun tinkering. I also got some #38 pilot jets to try out.
Mixture does richen up as the engine warms up, so that makes sense.... It seems like it does ok (maybe a bit rich) untill it warms up and then it just died.
From your description, flooding from overly rich mixture from the sharply tapered needles sounds likely. Either that, or you were running out of gas...is that possible?Setup: no airbox mods. Freshly cleaned K&N. Two bros racing exaust. Stock jets as far as I know.
1) Not sure really. I had just gunned it for about a block, then slowed down to take a corner and when I was accelerating out of the corner it started to sound like it was missing real bad (like running on 2 cylinders almost) and no throttle response. I held in the clutch and coasted for a bit trying to rev it with no response and then it died. I coasted into a parking lot and waited for a bit then tried to start it. It tried and fired once then wouldnt. I figured it was flooded so i let it sit for a few min and tried again.... nothing. So i started pushing because I wasnt going to leave it there. I tried to start it every time I took a break from pushing it the mile or so home but no luck.
I should re-set my mixture screws I guess :corner . they are at 2 turns.....
2)Yes it did feel a little boggy at 1/2 throttle. Felt good from closed to 1/2, and then after it got past the bog it felt fine and pulled like mad.
Any recomendation on the size of main jets?
Also is this worth persuing or should I just do stock needles and the #38 primary jets?
Thanks for the help!
The straight section at the top of the needle is the same length on the OEM needles. It is only the tapered section that is longer on the needles in carbs #2 and #3. I would think all the needles should be installed with clips in the same position.I was just reading through the thread again and had a major realization... I set the length of all the needles the same so the #2 & #3 cylinders have very short needles in them..... should probably fix that..... might help some things.
Yup, you've got the right idea. Moving the clip up(which moves needle down) will have the carbs operating on the straight section of the needle longer, and at full throttle will have a leaner mixture since you won't have moved as far down the taper. One possible drawback to this idea is a flat spot in the mid-throttle range if transition to the taper is delayed too much by setting the clip too high. The carbs do need some taping of the needle with increased throttle opening to keep the mixture optimum.I think I may try #105 main jets and see how that does. I dont want to give up on these needles yet! By the way, I really have to thank you gents for not getting fed up with all of my posts and questions On that note... I was doing alot of reading and it seems that people are changing shims and position of clips on adjustable needles alot..... what would happen if i lengthened the needles more (put the clips on the top-most slot? In theory wouldnt that make the usable part of the needle more of the straight part of the shaft and a little less of the dramatic taper at the end? Or would it just mean less range of throttle/shorter power band?
This is Excllent Info!Without complicating things overmuch I though some of you would be interested in my findings:
I have just obtained a'spare' bank of carbs to 'play' with, and to install an Ivan's jet jit in.
As I had the carbs apart I took the opportunity to meaure them up (as best I could with a vernier caliper).
My measurements for the stock needles are very similar to Bolserst's findings, plus I have added the dimensions of the Ivans needles.
N4MD (carbs 1 + 4)
Length of parallel section: 16.33
Length of taper section : 30.16
Maximum Diameter : 2.41
Tip Diameter : 1.90
N6NC (carbs 2 + 3)
Length of parallel section: 17.47
Length of taper section : 27.45
Maximum Diameter : 2.42
Tip Diameter : 1.87
Ivans Kit (all carbs)
Length of parallel section: 14.64
Length of taper section : 27.20
Maximum Diameter : 2.38
Tip Diameter : 1.72
The Ivan's kit also uses #105 main jets as opposed to the standard #108's.
The obvious thing about the Ivan's needles is that they a shorter effective length than both the N4MD and N6NC
needles, with a slightly steeper taper angle. The diameter of the staright section is greatly reduced.
So Bolserst's solution, found by trial and error, agrees closely with what Ivan's have been selling!
So now you all know how to get a cheap "Ivan's" jet kit.
As the title of the thread implies, there seems to be quite a bit a variance in how different ZR-7s run with seemingly indentical, or stock carb setups.So what are the best options for a stock setup. I don't really want to mess with the stock needles.