Mikuni VM float height

[tony27]

What is a baseline setting for the float height on a new VM Mikuni?
I just bought a new 36mm to complete converting my CZ to reed valve & suspect the float height is a bit high, the overflow tube has a bit of fuel sitting in it & exiting corners the motor isn't running clean
I tried lowering the needle to the top clip which didn't really help & because I was running the motor in I couldn't bring myself to spend the time at higher revs to get around it
Really need to sort before I go back to work tomorrow night as the next meeting is on Saturday
 

[Lozza]

Float height won't be affecting that, your looking at slide cutaway and needle jet , if the needle is running at the 1 or 5 positions you need the next richer or leaner tube

[bazza]

Tony check with hatrix Auz there base settings are very close

[sleepy]

From memory it is 17 to 19mm if it has the bent float arm. Definitely worth checking before diving into other changes, I've seen a few near new carbs lately with the float level to high.

[yamaico]

Float height certainly does have an effect Tony. Get that sorted before anything else. You can then start the tuning process proper.
As Mike says TD Hatrick will be able to help.

[tony27]

Float height is easiest to check at the moment. Just found the float height mentioned in the specs on Sudco's site as 17-19mm so I'll see where it is in comparison
I was supplied a jet kit for running the reed which from memory has a 6DP1 needle where the carb came with a 6FJ6 needle which looking at the chart are quite different, the 6DP1 is richer if I understand right
Both the needle jet supplied & fitted to the carb are the same 159-Q5 & I'm pretty sure I won't have any others in the 159 length or time to get 1 before the weekend

[yamaico]

The 6DP1 is richer at the top end but slightly leaner at the bottom end. That's the one I would be using if it's blubbery off the slide.

[tony27]

6DP1 is what is fitted at the moment, was supplied with the clip in #2 if #1 is the top notch, I tried the top notch & it was slightly better but still quite rich
Needles I could get delivered in the next couple of days are 6DH3, 6DH8, 6DP4, 6F5, 6F15, 6H2, 6DP10, 6N7. Quite cheap so I don't mind getting more than 1
Would you suggest any of these as a possible improvement?

[yamaico]

Hi Tony,
It's a bit hard without listening to the bike but I would probably pick the 6F5, followed by the 6DH3 and then the 6F16, the 6DF15 and 6DH8. I did a quick spreadsheet to compare them but I am O/S and don't have details on the 6DP4 or the 6H2, so that's about the best I could do. Like you say, they aren't very expensive and can go into the jets box for the future.
Pete.

[VMX60]

Tony
Had good results with 6F5 double taper 38mm Mikuni on the big bore ZEDS , no reed valve , running a 340 main Q6 needle jet
With a Reed have to come down on the main

Cheers

[yamaico]

Tony
Had good results with 6F5 double taper 38mm Mikuni on the big bore ZEDS , no reed valve , running a 340 main Q6 needle jet
With a Reed have to come down on the main

Cheers

Should be close then Tony as your Q5 needle jet is one step leaner than the Q6.

[alexbrown64]

Tony,
I bought a 36VM from MikuniOz.  When i fitted it to my 125, it was flooding so bad that overnight, it filled the cylinder.  I rang them up and he said the float was "factory set" and should be OK and not to touch it. I did some research and it was set wrong.  The floats and everything are different than the older ones, so i don't think you can use your old measurements from the original workshop manuals.
I just checked my notes, and i had to set the float to 22mm, and i believe i checked it using this method on YouTube.

https://www.youtube.com/watch?v=PHuB1lyagKM

Cheers,

[tony27]

Have ordered the 6F5 needle, hopefully it should be here Thursday as I will have ordered too late in the day
I'll check the float height tomorrow arvo before work to 18mm if it is less than 17mm, may just swap the arm out of the old carb that was used with the original cylinder & see what it measures.
I can't go off the Manual Alex as none off them give a float height for Mikunis as they weren't factory fitment even though they were commonly used

[yamaico]

Tony,
If you can't get a definitive measurement on the float height just lower it until fuel stops dribbling out the overflow. If the float level is too low it will give you a hesitation when you snap the throttle and it may well starve towards the end of conrod straight, but as you're probably not going to race it at Bathurst that won't be a problem. 
Pete.

[fred99999au]

Been thinking about float height versus fuel level and it strikes me that they might not be the same thing.

That video above is measuring fuel level, but it might not correlate to a defined 'float height' measurement from a manual, depending on float design, float arm design and carby design.

Or have I completely missed that point?