Heymow - Lawnmower Racing Forum

Engine Help => Kohler Engines => Topic started by: Big Mike on March 25, 2016, 08:15:42 pm

Title: Mikuni flat slide jets
Post by: Big Mike on March 25, 2016, 08:15:42 pm
Anyone know where i can buy a kit full of main jets for the mikuni 34mm having a issue where initial start power is great then dies mid range then picks up high side.
Title: Re: Mikuni flat slide jets
Post by: Jeff McKelroy on March 28, 2016, 02:44:51 pm
Sounds more to me like a metering rod being a bit too big or down too low. have you tried moving it one click up? If you do, and now top end is boggy, back down main jet on or two sizes.

I recommend to ANYONE who is going to use Mikunis to purchase a Sudco "Tuning Manual" book. There you will find all sorts of nice things, and TM/TMX carburetors are covered quite well.

All your jets are available there, and while I didn't look, you may be able to buy a complete kit.
Title: Re: Mikuni flat slide jets
Post by: BIG AL 202 on March 29, 2016, 08:59:39 pm
THESE CARBS ARE VERY TUNABLE! YOU HAVE 4 TUNING ITEMS, FIRST THE AIR SCREW ON THE SIDE, THAT WILL WORK AT IDLE AND JUST ABOVE NEXT YOU HAVE THE PIOLET JET NEXT TO THE MAIN JET INSIDE THE FLOAT BOWL, THAT COVERS ABOUT THE FIRST QUARTER THROTTLE. NEXT YOU HAVE THE NEEDLE IN THE SLIDE THAT COVERS FROM ABOUT QUARTER TO THREE QUARTERS THROTTLE, YOU RAISE OR LOWER THE CLIP TO RICHEN OR LEAN AIR FUEL (UP IS RICH DOWN IS LEAN) AND THAT WORKS OFF THE MAIN JET. THE NEEDLEPULLS AWAY FROM THE MAIN SO THE MAIN AND NEEDLE WORK TOGETHER. THE MAIN JET IS THE LAST QUARTER THROTTLE.
THERE IS OVERLAPPING OF THE JETS SO BY GETTING A JET CHART YOU CAN SEE WHERE YOU NEED HELP. A GOOD TUNING BOOK, LIKE THE ONE JEFF SUGGESTS CAN HELP YOU TO GET IT RIGHT WITHOUT SPENDING A TON OF MONEY JUST GUESSING!
TO ANSWER YOUR QUESTION TRY RASING THE NEEDLE 2 (THAT MEANS DOWN TWORDS THE POINT) IF THAT GETS BETTER, DEPENDING ON WHERE YOU ARE AT ON THE NEEDLE YOU MAY NEED TO CHANGE THE MAIN AS THEY WORK TOGETHER.
I HAVE TUNED ALOT OF 2 STROKES, IF YOU BREATH AT THEM WRONG YOU CHANGE JETS! (AT LEAST TO KEEP THEM FAST)
HOPE THIS HELPS!