Mikuni 38 on vanny 23

[sanddragbronco]

Anyone out there done a Mikuni 38mm on 23Hp Vanguard. Just put one on and jetting is way off. I have limited jets on hand right now so just looking for a baseline to get it close for now. Came with 180 main and 25 Pilot- way to lean! been jumping all over up to 280 main but i have very few pilot jets on hand. 260 on main seems to be getting close on high end but big stumble on the low side. Anyone?

Thanks

[opsled]

How does it idle with the 25 pilot?

You need to start there. Most engines that use a Mic (roundslide? I'm assuming) will get the idle jetting right with the pilot air screw set at about 1 to 1 1/2 turns out then start working on the main. WOT is set with the size of the main but transition from idle to WOT and midrange is set with the main tube and needle.

Most factory setups for an engine will have the pilot (idle) and main (WOT) factors figured out then work on transition off idle and midrange with different tubes and needles. Slide cut a way also plays into idle and transition. The ideal needle/tube combination will have the engine working as it should in the envronment it mostly runs in with the needle set in the center clip position and the pilot air screw at 1 1/4 turns out. This allows for adjustment to changing conditions.

I can't tell you what to run as I've never done what you're trying to do. There are some Mic tuning hand books out there that are very helpful with stuff like this.

Good Luck, Phil (opsled)

[fstg21]

You need a bigger pilot.

They are set lean from the factory. Assuming this is off a DRZ?

Or are you using a Super BN?

If it's a bn, it may be setup for 2 stroke, in a dual setup.

[sanddragbronco]

Carb is a new VM 38 round slide. It seemed to idle pretty good with the 25 pilot. I found a few other pilots and it is getting closer on the low end. I went up to a 60 pilot. The needle clip is on 3 (middle) and im at about 1-1/4 turn out on the air/fuel mixture screw. I think im getting pretty close. Plugs still seem pretty wet but I have had a lot of idle time on it- need a little run time to tell for sure.

[Factory-Fit]

Originally Posted by sanddragbronco

Carb is a new VM 38 round slide. It seemed to idle pretty good with the 25 pilot. I found a few other pilots and it is getting closer on the low end. I went up to a 60 pilot. The needle clip is on 3 (middle) and im at about 1-1/4 turn out on the air/fuel mixture screw. I think im getting pretty close. Plugs still seem pretty wet but I have had a lot of idle time on it- need a little run time to tell for sure.

Size is good, two 26mm stock carb chokes works out the same area as one 38mm, when you add the Performance Vee Twins plate that joins up the manifolds, each cylinder can suck from both venturis instead of just one.

This is great for top end, similar effect to bolting on what you have done, but some bad effects happen. I find running with the separate chokes even with a hot cam and high comp pistons makes the low end running a lot sweeter, but lost power at the top end. For a land buggy one carb will be harder to get right on jetting as the one cylinder will run rich and weird reversion effects come in.

I'm coming round to twin Mikunis as the Backwater Performance boys use

Kev
UK

[J.Cribbs]

Did you ever have any luck with this sandrag?