'98 25HP Merc having accellerating issues

[Square Grouper]

Just bought this motor used on Friday. Hung it on the skiff yesterday and took her out for a spin. Noticed right off the bat the engine was a little hesitant to get on plane. At WOT it seems it takes about 20 seconds or so before it kinda ?kicks? in and then yur off with no problem. Have no idea what it could be. You could hear a distinct change in rpm after about 20 seconds at wide open throttle. Otherwise the motor ran perfect. Any ideas?

 

[CharlieB]

Re: '98 25HP Merc having accellerating issues

Look at your spark plugs to see how blackened and sooty they are, it could be that they are near fouled out and time for a new set.

Carb settings possibly gummed up needing cleaning.

Try the new plugs, if it runs fine then quit while you are ahead, if it ain't broke......

But..... if it is still hesitant at all, clean the carbs.

 

[Square Grouper]

Re: '98 25HP Merc having accellerating issues

Thanks Charlie, I'll check it out. Any idea what plug is spec'd for that motor?

 

[CharlieB]

Re: '98 25HP Merc having accellerating issues

2 stroke NGK BP8H-N-10


4 Stroke NGK DPR6EA-9

 

[Square Grouper]

Re: '98 25HP Merc having accellerating issues

Pulled the plugs last night after work. One was a champoin plug and the other was an NGK but not the correct one. Both were fouled looking. GUnna pick a couple of the correct plugs up today and try to find a day after work to run her again. Thanks Charlie

 

[Square Grouper]

Re: '98 25HP Merc having accellerating issues

Well plugs didn't fix the problem si I guess the carb is next. Pull it off and clean it??? I'm no carb guru but sure want to try avoid spending a lot of $$. Man this is aggravating, especially for an engine I bought that supposedly was just serviced and ran perfect.

 

[ghs53089]

Re: '98 25HP Merc having accellerating issues

Ive got the same issue with my 97 25hp merc. I had the carb cleaned and rebuilt but i still have the issues. let me know how it goes for you.

 

[CharlieB]

Re: '98 25HP Merc having accellerating issues

These little two strokes only need a few of things to run well. A little attention to detail and your motors generally run just fine.

Compression, anything over 100 is acceptable, the more hte better, 120 average, biggest thing is that all cyl's be consistant or within 5% each other.

Spark, must be able to ZAP a crisp bright blue arc 7/16 "

CLEAN carb jets

Good fuel pump AND hoses

Proper adjustment of timing and carb opening

Idle mixture set to fastest/best idle IN GEAR and IN the water PLUS approx add'l 1/8 turn

NEW water pump impeller every other year, to be sure you don't melt those pistons.

 

[OldMercsRule]

Re: '98 25HP Merc having accellerating issues

Ive got the same issue with my 97 25hp merc. I had the carb cleaned and rebuilt but i still have the issues. let me know how it goes for you.

I'd first check the compression n' make sure the two holes are close n' North of 100 psi.

Then run some Seafoam in the fuel fer an hour or sooooo before ya get yer wrenches out. I would also (after one hour runnin' with Seafoam in fresh premix fuel), DE CARB THE engine with a can of POWER TUNE or similar decarb stuff.

Seafoam also de carbs the darn thing.

Leave her sit fer at least 48 hours after the sprayed de carb, then follow the instructions on the can, fire her up n' run her real hard fer 30 minutes ta blow out all that carbon. If that doesn't werk get out the wrenches n' deal with that carb.

Me over priced $.02. JR