120 looper bland performance (better than before but not good enough)

[alden135]

Thanks to all over the spring/summer for the extensive help with my motor. I still don't think I'm getting the horsepower I should though.<br /><br />Performance now: J120TLES<br /><br />23mph @ 3700 rpm (omc guages) WOT<br />Starts great<br />bulb stays firm<br />125 125 125 124 psi<br />motor fully trimmed does not signifigantly raise rpms much.<br /><br />Whats been done:<br /><br />power pack, wires coils, plugs, timer base, fuel filter, carbs serviced, decarbed, timed, link/sync, changed 14X19 prop to 13 3/4 X 15 omc almn. <br /><br />I'm not yet seeing all this tourque and power so many here profess this thing should have. Any ideas?

 

[MCM]

Re: 120 looper bland performance (better than before but not good enough)

Hi Alden,<br /><br />What size boat, aprox. surface weight are you pushing?<br /><br />Mike

 

[alden135]

Re: 120 looper bland performance (better than before but not good enough)

Hi MCM, It's the 20' Sunbird in the avatar, but I don't know the weight of the boat.

 

[MCM]

Re: 120 looper bland performance (better than before but not good enough)

Alden, <br /><br />Sounds like about the right prop but that doessn't take into account boat load, if you've got that boat loaded down to the gills you might consider an even lower pitch than that.<br /><br />Check these out<br /> http://www.miwheel.com/MIWheel/html/products/outboard/PSResults.asp <br /> http://www.miwheel.com/MIWheel/html/products/outboard/PSResults.asp <br /><br />Sounds like you've done about eveything else to improve perf. unless you got something going on with your L/U.<br /><br />Mike

 

[alden135]

Re: 120 looper bland performance (better than before but not good enough)

Those numbers I gave were with an unloaded boat. With bags and passengers it's worse. When I bought it there was a 14x19 prop on it and lots of water toys in the boat ie, knee board, tube etc. I can't imagine why the performance is what it is now.

 

[MCM]

Re: 120 looper bland performance (better than before but not good enough)

Alden,<br /><br />Certainly sounds like something else goin' on then.<br /><br />You could have picked up some slippage in your throttle cable I s'pose. Have someone advance the throttle to its full stop and watch to see if its actually getting to where its s'posed to be at the motor, <br /><br />Just a thought!<br /><br />Mike

 

[alden135]

Re: 120 looper bland performance (better than before but not good enough)

Thanks for the replies MCM. I'm afraid I've tried all the stupid things like checking throttle plates and such. I'll just have to keep poking around with things. The good part is I'm learning a lot about outboards. Maybe in 500 years I'll know 25% of what Joe Reeves knows now.

 

[Walker]

Re: 120 looper bland performance (better than before but not good enough)

alden, get yourself an inductive timing light and try it on each sparkplug wire while you are running the boat under a load. I just can't understand your performance unless you are running on 3 cylinders.

 

[MCM]

Re: 120 looper bland performance (better than before but not good enough)

Well, if its any consolation at least you can get yours to start. I've still got ign. problems from hell. Replaced stator, power pack, plugs, ruled out ign. switch. If its above 70 deg. I get spark, below that & nothing. New coils should arrive today, hopefully thats where the prob. lies because I'm running out of parts to replace and money!<br /><br />Good luck,<br />Mike

 

[alden135]

Re: 120 looper bland performance (better than before but not good enough)

Originally posted by Walker:<br /> alden, get yourself an inductive timing light and try it on each sparkplug wire while you are running the boat under a load. I just can't understand your performance unless you are running on 3 cylinders.

Did that already. Good spark with my spark tester too. All plugs look the same. There has to be something stupid being overlooked.

 

[papasmurf]

Re: 120 looper bland performance (better than before but not good enough)

Are both carb throttle plates opening all the way?<br />Stator output good?<br />Boat bottom clean?

 

[alden135]

Re: 120 looper bland performance (better than before but not good enough)

Originally posted by papasmurf:<br /> Are both carb throttle plates opening all the way?<br />Stator output good?<br />Boat bottom clean?

Papa,<br /><br />1. yes, 4 carbs<br />2. I don't know, but never had dead battery <br />3. yes

 

[MCM]

Re: 120 looper bland performance (better than before but not good enough)

Alden,<br /><br />You've got good spark, good compression.<br /><br />Sounds like its leaning (no pun intended) alot towards fuel/carburetion.<br /><br />How's the fuel pump? check for air/vacuum leaks. Verify carb adjustment settings.<br /><br />Were the carbs rebuilt or just cleaned?<br /><br />Mike

 

[Dhadley]

Re: 120 looper bland performance (better than before but not good enough)

Whats the timing set at?

 

[alden135]

Re: 120 looper bland performance (better than before but not good enough)

18 degrees

 

[papasmurf]

Re: 120 looper bland performance (better than before but not good enough)

Technically that has 2 two barrel carbs. The stator charges the battery but also provides the voltage to the ignition system. Have you tried running on a seperate fuel supply?

 

[Walker]

Re: 120 looper bland performance (better than before but not good enough)

That motor has 4 carbs mounted to 2 throttle plates. <br />Does it start easy? How does it idle? Is full throttle smooth just slow or is it rough?<br />Any plugs have black carbon on them?

 

[papasmurf]

Re: 120 looper bland performance (better than before but not good enough)

No! That motor has 2 single barrel carb bodies, mounted on a throttle plate, which make up a single carburetor.

 

[G DANE]

Re: 120 looper bland performance (better than before but not good enough)

Did you ever check the reeds, before replacing ignition parts. a non functioning reed will make cylinder non-working at all. It will also leave a spark plug wet with gas, but not wisible after iddle right away, unless you check plugs after a rapid stop, from running WOT for half a minute or so.

 

[alden135]

Re: 120 looper bland performance (better than before but not good enough)

Well guys, <br /><br />However many carbs there are, I took off 4 things with floats in them and kitted them.<br /><br />GDane <br /><br />I did not remove the throttle plates and check the reeds. What would I be looking for? I have checked the plugs after various types of running and always the same thing, light coat of oil and even appearance.