Mikuni Tuning

[DLDeere]

My 295/S stalls when opening the throttle from idle. Carbs have been thoroughly cleaned. I replaced the inlet needle and seats with genuine Mikuni parts. New pilot jets #35, new main jets #140, clip on jet needle is set at 3. I started with the air screw 1 turn out, but it seems to be the best at 1/4 - 1/2 turns out. Book says set idle at 2200-2400 rpm. I have idle stop screws all the way in and can only get to about 1600 rpm.

Once past the start, it runs great. It's just the first opening of the throttle that it stalls. I believe it's too lean, but not sure how to change that at idle.

Any suggestions?

Howard

[400brian]

You can try raising the needles by lowering the E clip one notch.

If everything else is working, you may have to go up to #40 pilot jets.

[DLDeere]

I'll try the larger pilot jet. Thanks.

[HoosierDeereMan]

Howard,

I wonder if your #140 main jets are just too lean? I'm thinking 3/4 to 1-1/4 turns out on those air screws is where you should be. Anything more or less would mean you need to change main jet sizes. I'm betting if you installed larger main jets and got those air screws set 1 round out you would eliminate that stumble. The main jets will effect the entire system. I'm also betting you are lean on top end as well. What do your plugs look like?

The factory settings were #160 main on the mag side carb and #190 on the PTO side carb.

Troy

[400brian]

When messing with card adjustments, the engine needs to be warmed up, idling in the shop won't do it.

[DLDeere]

Troy,
You might be right on the main jets being too lean, but I didn't think that would have an affect until at 3/4 throttle or more. Will it make a difference on take off from idle? Haven't run it wide open enough to get a read from the plugs. Actually haven't been to full throttle at all yet.

Also, are you sure on the factory settings for the 295? My service textbook shows 140 factory installed and 130's and 150's in the tool pouch.

[JDXspec]

there was an update in the 295/s service textbook stating that 160-190 should be used to start with. I found this is normally pretty close to what you end up with

[HoosierDeereMan]

Howard,

I was struggling with this as well. So I asked Jerome Kretzman, ETD mechanic.

"When you lean down the top the end, main jets, you lean down the whole system. You can also adjust the low speed air screw. Turning the screw in, shuts off the air and causes a richer condition. When you turn the screw out, it provides more air and causes a leaner condition. Normally you can determine pilot size by adjusting the low speed air screw. If you turn the air screw in to 1/2 a turn or less to get it to run good, you need a bigger pilot. When you turn the air screw out over 1-1/2 turns to get it to run good, you need a smaller pilot." ---J. Kretzman.

I hope this helps. It sure did in my case!

Troy

[DLDeere]

I'll try it. Biggest I have right now is 150, so I'll give that a try and see if it helps. If it helps, I'll pick up some larger ones and keep going from there. I'll see if can get 160 and 190 this weekend in Waconia. Thanks for your help!