135 Optimax running a little slow

[holmsvc]

My 135 Optimax started running a little slower than usual. It starts and idles just fine, but is running about 5 to 10 mph slower and is not getting up to speed quite as quick as usual. Any ideas?

[holmsvc]

There is typically around 50 people viewing this form and no one has any suggestions?

[BoxMN]

Give some more info. How many RPMS last year, how many this year? Did you check the prop for any dings? Old gas, new gas? What year is the motor? (i.e. old plugs...) You say it is getting up to speed, but not as fast... but is it getting ALL THE WAY up to speed, or a few mph short at WOT.

Here are the easy things, after that you more help than I can give

dings on prop (even a little ding can affect it pretty big)

bad gas (though would likely idle worse)

old spark plugs? I'd change them anyway if older than a couple years

weight different in boat (i.e. LOTS more weight in front of boat)

Good luck, hope you can find problem, as it stinks to have motor issue. But that is a bullet proof motor, so hopefully simple issue.

[Black_Bay]

My guess is you may be down one cylinder. You may have a bad plug or coil.

[Deershooter]

I just had the same problem with my 150 and it ended up being the battery. The voltage was still fine but it was just getting weak.

[PTocko]

My 135 Optimax started running a little slower than usual. It starts and idles just fine, but is running about 5 to 10 mph slower and is not getting up to speed quite as quick as usual. Any ideas?

Folks are right, "a little slower" is quite subjective and could be as simple as it is now warmer and EVERY motor makes less power the warmer it is. What RPMS etc, if off by more than 2-300 then probably something else. If not then I would chalk it up to it being summer. Good Luck, Paul