34 mm twin mikuni jetting.

Status
Not open for further replies.

hillbone

VIP MEMBER
Joined
Aug 24, 2009
Messages
207
Country flag
hi. I want to go with a pair of mikunis on my 850. i appreciate it will take a fair amount of testing to get it right.
Can someone give me a starting point for the jets, slides, needles etc. i,m hoping someone has a good set up that will be a great start. I run the larger diameter headers and mufflers, 60 thou oversize and stanadard porting and cam. i dont have a book or guide so your info will be a great start. cheers mark
 
Victory library tuning guide .... Rocky Point ... your own experience ...
Craig
 
hillbone said:
ta . just bought the tuning guide for mikunis .


Let us know how that base setting of theirs works out for you.

I have twin 34mm Mikunis, but I don't plan to use them on a road bike. Which means I am not restricted by the short splayed manifold and the frame.
 
hillbone said:
hi. I want to go with a pair of mikunis on my 850. i appreciate it will take a fair amount of testing to get it right.
Can someone give me a starting point for the jets, slides, needles etc. i,m hoping someone has a good set up that will be a great start. I run the larger diameter headers and mufflers, 60 thou oversize and stanadard porting and cam. i dont have a book or guide so your info will be a great start. cheers mark

This is strikingly reminiscent of your very 1st post back in 09.

Here is what I think is the poop on twin Miks. It is a given that a single Mik, unlike the Amal, has an incredible number of jetting combinations and the suggested starting point is just that, a suggestion. No 2 Norton's breather exactly alike and therefore it is somewhat excepted that there will be some adjustment to be made in this regard.

Let's say that there are 10....no 20 possible adjustments whether the main, pilot, needle, needle jet and so on, to be considered. This means that there will be the same to be consided for the second carb. You can get away with a wide range of adjustments with the screws on an Amal whereas the Miks and jet adjustment dependent with a narrower range available with the screws, being a fine tuning situation.

So, you have roughly 20 jetting possibility with one Mik (base around a suggested starting point), and 20 for the second Mik. One might think that this adds up to 40 possibilities, for although no 2 Norton's breath alike, the Mikuni's will surely show with their finer adjustments that no 2 cylinders breath exactly alike either. (hence the balance tube that people be hashing over).

So, instead of assuming 20 + 20 equals 40, It may be more realistic to say that 20 X 20 = 400.
Anyhow, good luck with that idle.
 
pete.v said:
hillbone said:
hi. I want to go with a pair of mikunis on my 850. i appreciate it will take a fair amount of testing to get it right.
Can someone give me a starting point for the jets, slides, needles etc. i,m hoping someone has a good set up that will be a great start. I run the larger diameter headers and mufflers, 60 thou oversize and stanadard porting and cam. i dont have a book or guide so your info will be a great start. cheers mark

This is strikingly reminiscent of your very 1st post back in 09.

Here is what I think is the poop on twin Miks. It is a given that a single Mik, unlike the Amal, has an incredible number of jetting combinations and the suggested starting point is just that, a suggestion. No 2 Norton's breather exactly alike and therefore it is somewhat excepted that there will be some adjustment to be made in this regard.

Let's say that there are 10....no 20 possible adjustments whether the main, pilot, needle, needle jet and so on, to be considered. This means that there will be the same to be consided for the second carb. You can get away with a wide range of adjustments with the screws on an Amal whereas the Miks and jet adjustment dependent with a narrower range available with the screws, being a fine tuning situation.

So, you have roughly 20 jetting possibility with one Mik (base around a suggested starting point), and 20 for the second Mik. One might think that this adds up to 40 possibilities, for although no 2 Norton's breath alike, the Mikuni's will surely show with their finer adjustments that no 2 cylinders breath exactly alike either. (hence the balance tube that people be hashing over).

So, instead of assuming 20 + 20 equals 40, It may be more realistic to say that 20 X 20 = 400.
Anyhow, good luck with that idle.

On the other hand......there are plenty of bikes out there with twin Mikuni VMs that work fine....they just may not be Nortons!
 
hi. I guess i was trying to see if there were any common success stories or denominators out ther that may have helped. Yes , i did post the same question years ago and recieved more philosophies than data so i put in the too hard bin at the time . im happy to pkay around with it off course, but no harm in asking before i waste money on long shots. thanks steve for the tip on the manual . they suggest the following.
Main jets drop 10% from single . i will try 230's.
pilots . subtract 5 to 10 from single. i have a pair of 22.5 according to my poor eyesight.
Slides drop .5 . i will try 2.5's
needles use same 6DH3. they suggest a needle jet of p4 to p6 . i have a pair of p8's, might be too rich and a pair of P0,s. i wonder if I can raise or drop the needle to compensate for either? anyone have a thought here?
cheers hillbone.
 
Status
Not open for further replies.
Back
Top