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Anyone have any experience with a VM24 on their 350? Not there yet on my project but carb kit is on the way. Just wondering if anyone has a good base line to start from with jets. I live at about 352m or 1100ft above sea level - how’s that for extra info lol. I know lots of variables but I am all ears!
Thanks

I think that your size is too small, most low-tuned 350's would go with a 28 or 30mm. I think that you will struggle to find anyone with experience of a 24mm, but you may get data for a 250 and go from there.


Colin

Thanks Colin. Yeah it was the last carb on the bike but these ears have never heard it run so will be interesting to see how she goes. Thanks for the tip. Guess it could come down to how it actually has possibly been jetted too….

Duccout wrote:I think that your size is too small, most low-tuned 350's would go with a 28 or 30mm. I think that you will struggle to find anyone with experience of a 24mm, but you may get data for a 250 and go from there.


Colin

Here’s a question, how do guys route their over flow lines? There are two on these carbs. Hate the thought of any fuel spilling out potentially on the bike.

I have just left mine as they came!

From my own experience, the same carb settings work for both Mk3 and (standard) Desmo models.

Dan C reported the following for his 350.

Re: Mikuni Carb Settings
by Dan C » 03 Apr 2020
Just an update on what I've found so far on widecase 350 desmo with VM30 Mikuni

Pilot jet. Started with a 40 which is too rich. Went down to 35 and still too rich. Installed a 30 but haven't tested that yet.
Needle 6F5 and Needle jet P5 (159 series). This is the combination that it shipped with from Mikunioz and seems to be spot on for the midrange.
Main jet 250 as shipped. I haven't done a WOT test for the main so don't know about that yet.
Hope this might help anyone else thinking about a Mikuni. I'm very pleased with it.
-----

Later Dan C published the settings that he is using with a Mikuni 30mm carb that he has fitted to a 350 Desmo widecase engine earlier in this thread. Page3, 4th entry on page:-
On 1969 350 Desmo.
Pilot 30, Needle 6F5 on middle notch, Needle Jet P5, Main 160, Air jet 2.0, Slide 2.5
Similarly these settings on this bike are giving nice tan coloured plug readings throughout the rev range. Bike starts easily, idles and revs cleanly at all throttle settings.

Duccout wrote:I have just left mine as they came!

Hehe. Yup if I set my float right and use my shut offs no worries right?!

Assuming this VM24 was running on this bike(as it came with it) the spark plug gives evidence of it running rich. Is it even within the realm of possibility to get this jetted to work on a 350?

I dunno. I fitted a VM28 to my 250 because of Mikuni's reputation as a good carb, and the fact that it is properly rubber-mounted, but as it was delivered it was weak low down, was almost impossible to keep the bike running when cold and the plug showed a very rich mixture. After a lot of fiddling I have it running well now, but the plug is still black, and it still plays up when cold, a problem that seems common to Mikunis, according to what I have read, so I am not sure that it was worth all the hassle, when an Amal is a bolt-on fix.

Colin

In my opinion fitting a 24 to a 350 is going to be underpowered and nothing but trouble. After spending to much time and money you might think about a larger carb.