Hi what alternative carbs are you guys using anyone tried 40mm pwk

I run Mikuni VM38-9 roundslides and previously also ran TM38 flatslides.

Because I got asked so often, I even made a basic guide for the conversion. (The same is available in this forum in German, but somehow I think you'll prefer the English-language original.)

https://greasygreg.blogspot.com/2019/08/everyday-tr1-all-new-vm38-9.html

And Ali (amongst others) have done something rather similar (again, in German) for Dellorto 40ies. Here on the forum it is available in the following thread:

https://www.tr1.de/pages/forum.php?iQuery=num=1353751281

Hope this gives you an idea.

Cheers,
Greg

Many thanks

I've got a couple of vm38 mikunis used I think they were previously used on a 2 stroke so I need help with jetting I see Greg used 17.5 pilots 175 mains but what about needles an needle jet and any other jets there might be

Other than those two jet-swaps, my carbs are following the VM38-9 configuration:

Standard Jetting Specifications
Carburetor #      Venturi Size      Main jet (VM4/042)      Pilot Jet (VM22/210)      Needle Jet      Jet Needle      Throttle Valve      Air Jet      Needle Valve
VM38-9      38      330      30      Q-2      6DP01      2.5      0.5      3.3

The two stroke version (unless it's an OEM carb, than all bets are off) - is jetted quite differently, so you basically have two swap all internals except the slide:

Carburetor #      Venturi Size      Main jet (VM4/042)      Pilot Jet (VM22/210)      Needle Jet      Jet Needle      Throttle Valve      Air Jet      Needle Valve
VM38-21      38      360      40      Q-0      6DH3      2.5      2.5 Body      1.5