jet needle ?

[nd jat]

I'm using 28 vm mikuni carb on stockish blaster. mods are pipe, no lid, uni filter. Main question is on about the sizes of the needles? Most needles that I can get don't have dimensional sizes to them. So that makes getting needles a guess work at best.

The needle I have is 5DP7, I know it's dimensions. I have found charts that have it. But the ones I'm wondering about aren't given on jetrus. And forget about the blaster's stock 5J22 needle. I'm basically looking to find a needle in between these two cause 5DP7 is too lean in mid and the 5J22 is too rich on the later mid. I'm now looking at 5DP39, 5F3, 5F12, and 5FP17. the last 3 I'm guessing if they are what I'm looking for as dimensionally close to my needs.

So if any one knows the dimensions of these needles that would be great.

I know the needle jet may need to be changed as well, But haven't looked into what size it is yet. Or if I can change it. The carb was off of some trials bike of unknown year or exact bike, But jets it had were more than likely suited to that bike before I swap it in on the blaster.

 

[nd jat]

I take it no one knows these? at least anyone that's looked.

 

[Blaner]

oh dear, no needle fundis here... hopefully someone can chime in

 

[nd jat]

The biggest problem is not knowing the exact dimensions. That could help steer me where I need to go. I've come across lots of info searching. Plenty of needles that could work, but aren't available. At least as far as I can tell. Unknowns suck!! I know that 28 mikuni's often came with 5F6 needles if bought as replacement carb. That's were I'm focusing for needles for a base line.
Guess a caliper is going to be my best friend when I get these needles in. Just dislike guessing as to what may work.
best info I found was this.
Mikuni Jetting Info
maybe some one else can take advantage of this info on their application.

 

[nd jat]

Well got the needles in. 5FP17 looks to be my best bet on the needles. Will see how it performs. 5F3 is tiny won't work without changing needle jet (emulsion tube). 5DP39 is iffy at best, And the 5F12 looks better than 5DP39 but not by alot.
The main thought that has crossed my mind is there maybe a lot of ppl that fry their motors when or after changing carbs. There isn't a lot of info on mikuni jet needles and even less with sellection. Many may try to compensate with their pilot and main like me, and be a nut hairs close. I'm just glad that I caught it before I fried my motor. I ran mostly wot or close to it most of the time. But when I ran at a little over half throttle that's were I had a close call. I still have 120 + psi but I'm still on first bore.
I do hope this may help some ppl about something that maybe over looked when changing carbs. I know that many places may send a needle that will work for a given motor cc's but those that buy used my have a ticking time to fring their motor.
I can also see why many go to Keinin carbs.