Yamaha 25 HP 2-stroke hard starting

[25_hp_xd_man]

Re: Yamaha 25 HP 2-stroke hard starting

OK, I have read what all have had to say about this yammy motor. I dont think anyone has correctly diagnosed this motor. I have a 2007 25 hp yammy smh also. First let me say these are very strong and dependable motors AS LONG AS THE CARBS ARE SET UP CORRECTLY. Second, let me say that no one has addressed one of the main symptoms mentioned by Jim. The motor smokes like hell when first started. Big clue as to what is going on in my opinion. I had the exact same problem. Intrestingly enough, the lower the motor was trimmed, the harder it is to start and the more it smoked when started. What does this tell us? Float height. If your motor is trimmed all the way up, I am pretty sure you would see an improvment. If not, your float is way out of adjustment. On the boat I run my 25 on, I have to pretty much use the bottom trim pin to keep the boat from "porpoising". With the factory float height you may experience hard start and hellacious smoking upon starting in the full trim down position. Easy solution. Pull the carbs and adjust the float tab to "lean" the motor in the down position. What is happening, the the float is dropping to low and opening the jet allowing to much full into the engine during the start cycle. Hence the excessive smoke and hard starts. Good luck with your motor

 

[rivvy]

Re: Yamaha 25 HP 2-stroke hard starting

I have the same motor and had the same hard starting when cold.The solution is to adjust the neutral throttle stop(set screw) to allow more air/fuel into the engine.Full choke and primer pumped about five times.Yamaha primer bulbs are stiff and it will require some experimentation before you find the ideal pressure/pumps to fill the float bowls.Be ready to throttle down once it starts as you don't want to over-rev. a cold engine.These are excellent engines and hold there
value(2-strokes are no longer imported to North America).Using fresh ethanol-free gas also helps starting.

 

[Bamaman1]

Re: Yamaha 25 HP 2-stroke hard starting

On all starting problems with 2 strokes, I take it step by step. Then I see step by step if the problem's solved.
Step #1--put new spark plugs in it.
Step #2--check the fuel filter and use fresh gasoline. Be quick to replace it.
Step #3--check out the fuel line and bulb. There again, be quick to replace it.
Step #4--disassemble the fuel pump to see if the rubber membrane is good.
Step #5--remove, disassemble, clean and reassemble the carb's. Needle valves can often stick which shows up as a drip, drip, drip after you shut down the engine after running it. No kit is required--just a can of carb. cleaner. It's maybe a 15 minute job on 1 carb.

Only after all this is done do you go further--like checking compression etc. Chances are the engine's not worn, and the problem's in the above items.

 

[tcfeet]

I have a 2006 25 ESH yamaha that has been a pill to cold start after sitting 2-3 weeks. After the first start, just point at the starter button and it fires up.
Runs perfect. After reading the old post about the choke flaps, I went out and checked mine. The top carb had a small gap in the closed position, hardly an 1/8" and the bottom one was closed all the way. After adjusting the linkage and closing the top butterfly, it now starts with little effort while cold.
Thanks to whoever posted that tip..