VM36 Jetting

VM-34, VM-36, VM-38 TM-36, TM-40 (HS-40) Sizes and tunings

Great tuning manual for Mikunis TM-36, TM-40 and HS-40
www.mikuni.com/pdf/hs40_manual.pdf

VM34-168

Engine side:40mm, Aircleaner side:58mm

This from Spindlehead in regards to a VM34-168.:
[If you have:
aftermarket intake (e.g. K&N, Uni, or other free-flowing device) AND
a freer flowing aftermarket exhaust (e.g. supertrapp),
then a 240 main,
25 pilot,
P8 needle jet, and the 6DH4 needle that comes with the carb is a good start.

If you have:
aftermarket intake (e.g. K&N, Uni, or other free-flowing device) AND stock exahust
then a 240 main,
25 pilot,
P7 needle jet, and the 6DH4 needle that comes with the carb is a good start

I suggest buying main jets 220-260; pilot jets 25, 27.5, 30; and the P7 and/or P8 needle jet.


VM-36

Most stock VM36's come:
Mikuni VM36 round slide carburetor:
Jet sizes : Main : 310; Pilot : 35;
Needle : Q-5;
Throttle Valve : 2.5;
Jet Needle : 6FJ6;
Air Jet : 2.0.
Engine side:43mm, Aircleaner side:62

Curley's setup VM36"
Here's my VM36 specs
Pilot 35
Main 230
Slide 2.5
Jet (needle) P2(188) custom drilling 1or2 thou larger
Needle 6FJ4/7 Top clip with a shim


VM-38
Engine side:43mm, Aircleaner side:62

StewRoss VM-38 tuning recommendation:
280 main
30 pilot...possibly too small?
Needle 6F8/2
3.0 slide cutaway

Perhaps a P4 needle jet...

Powerjet is blocked off...

I have several lots of 38 settings, so to totally confuse you here are some more:

240-270 main
30 pilot
Needle 6F8/2
P4 NJ
#2 air jet
1.5 slide cutaway

or

270 main
35 pilot
Needle 6F8/3
P6 NJ
#2 air jet
7.0MM slide cutaway (MEASURED)

ColinJAys race engine with a VM38:
230 Main
6F9 needle on the 2nd clip
P-6 needle jet
#2.0 Slide
20 pilot jet

TM-36-68


Most stock TM36-68 flatslides come stock like this:
42mm air spigot (engine side of carb)
54mm-air cleaner side
Jetting: 130 MJ,
12.5 PJ,
P8 needle jet,
2.0 Slide,
1.0 airjet.
Engine side:42mm, Aircleaner side:54mm
From what I can glean at this sight this is a good starting point for the TM36-68 for stock SR 500.

Greymin's tunings for the TM36:
pilot 17.5 screw 1.25 turns out
main 150
needle clip second from leanest
factory default needle jet (p-8) and needle.

"I get 50 mpg. and I ride 45 miles a day round trip to work.
I also backed the pumper adjustment way off for better economy.
It won't really buck until I lug it under 2750 rpm. My old bike with stock carb would buck at anything below 3 krpm.
11 discs in the Trapp."



TM-40 or HS-40
Engine side:43mm, Aircleaner side:55mm

Steve's suggestion for a HS-40 (same as TM40) pumper flatslide:
I don't know if this will be any help but the HS40 that I just put on had a #150 main (actual size=1.50mm) and 17.5 pilot jet but was slightly too rich at full throttle so I just went down to a #140.


What about all of these snowmobile VM36 and VM38 (mostly VM38s) carbs sold on Ebay? What is the electrical cord for? Heat? I would guess you might have to change evey jet in them.

Cliff