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

[Goodoleboy]

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

If I were trying to track down sorce of low Wot rpms . I would pull plug wires one at a time while at wot to find out which cylinders are not delevering power.<br /><br />Then I would have an idea as to which cylinders to work on. <br /><br />If you get no change or very little when plug wires are pulled one at a time, Then you can almost bet the farm that its a fuel delivery problem and not an ing. problem.<br /><br />My first suspession would be an air leak. Beleive me they can be tuff to find sometimes.<br /><br />My next guess would be one of the carbs is still dirty not delevering fuel at wot.<br /><br />Once you have pulled the plug wires while under full power, Then tell us which cylinders were not makeing any difference at all. (carbs feed dif. cyls)<br /><br />Ofcourse you know not to rev this motor while on the muffs. Got to have a friend to drive boat while you pull wires, with insulated pliers.<br /><br />Good luck!

 

[alden135]

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

Originally posted by Goodoleboy:<br /> <br /><br />If you get no change or very little when plug wires are pulled one at a time, Then you can almost bet the farm that its a fuel delivery problem and not an ing. problem.<br /><br />My first suspession would be an air leak. Beleive me they can be tuff to find sometimes.<br /><br /><br />Good luck!

What if I don't have a farm? <br /><br />I wonder if the air leak theory should be where I spend more time looking. I haven't found one yet but I've repeatedly checked fuel/spark things since the beginning.

 

[rodbolt]

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

alden<br /> before ya get all yiggy,boogie on down to your trusted dealer and rent/borrow his test wheel. I dont have the part number but he will. run it up on the test wheel and see if it will turn the test wheel to the specified RPM. if it wont you can now use the test wheel for troubleshooting. if it will you now will know its a hull/prop issue and not a motor issue. also use an inductive tach to verify your hull tach, would not be the first incorrect tach or tach signal I ever saw.

 

[alden135]

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

Originally posted by rodbolt:<br /> alden<br /> before ya get all yiggy,boogie on down to your trusted dealer and rent/borrow his test wheel. I dont have the part number but he will. run it up on the test wheel and see if it will turn the test wheel to the specified RPM. if it wont you can now use the test wheel for troubleshooting. if it will you now will know its a hull/prop issue and not a motor issue. also use an inductive tach to verify your hull tach, would not be the first incorrect tach or tach signal I ever saw.

My local dealer will not rent or loan anything, I'll just buy one if I really need to. I'm assuming it needs to be in the water and not on muffs.

 

[Goodoleboy]

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

Sometimes you can find them on Ebay. Yep they have to be in the water just like a prop. Test wheels dont have thrust so you can set dead in the water and rev er up. <br /><br />To find an air leak the old grease on the connection trick works purty slick...Grin!<br /><br />Smear grease on all connections from tank to motor. Then if your WOT improves start wipeing clean one at a time, When motor drops down on rpms then you have found your leak.<br /><br />Once you have checked line to motor and no leak found, Then start inside the cowl. Grease trick from fuel filter to each carb and so on.<br /><br />I think you are loseing power on two cylds. Just one wouldnt drop rpms that low I dont think.<br /><br />Or it could be none of the cylinders are getting enough fuel to develope full power at wot.<br /><br />And buy a farm so you have something to bet with. Naw mabey not, They can be more troubles than an outboard...If ats possible....grin!<br /><br />Good luck!

 

[G DANE]

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

If your speed is fairly accurate, you have around 8% slip, which is quite normal. That leaves a malfunctioning tach out. Speed, pitch and RPM's all fit in. How fast do other Sunbirds ( great boat btw ) run, with what horsepower. Did it go faster before ??

 

[papasmurf]

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

You might check around for a dealer with a dyno. Let him run it up on it. Solved alot of problems using a dyno. It is better than hanging over the back of a boat trying to pull the plug wires.

 

[alden135]

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

Originally posted by G DANE:<br /> If your speed is fairly accurate, you have around 8% slip, which is quite normal. That leaves a malfunctioning tach out. Speed, pitch and RPM's all fit in. How fast do other Sunbirds ( great boat btw ) run, with what horsepower. Did it go faster before ??

But why would the rpms max out less than 4k? That's what I don't get. I don't know how fast it used to be as since I bought in in the spring it's been a work in progress. <br /><br />I do like the boat a lot. It has pretty good sea keeping abilities and is real solid. Just don't wanna run the rpms low for another season and blow something apart.

 

[alden135]

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

Originally posted by papasmurf:<br /> You might check around for a dealer with a dyno. Let him run it up on it. Solved alot of problems using a dyno. It is better than hanging over the back of a boat trying to pull the plug wires.

Don't have many dealers around here. I'll start poking around in Maine for one with a dyno and see what they charge.

 

[Walker]

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

2 more questions. What plugs are you running and what are they gapped at?

 

[G DANE]

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

When you dropped in pitch, how much did the WOT rpm raise ? My comment on tach was only to rule out that the tach read too low rpm's. There is a problem somewhere. It isnt compression, which leaves out bores, gaskets, pistons, rings and other internals. It has to do with ignition, carbs, fuel delivery or reeds, supposing exhaust is open as it should. Running with a test wheel just once will tell you how much horse power you have. Will it go right up to WOT rpm or do it hesitate somewhere.

 

[G DANE]

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

I know a leak-down test tells more than compression numbers, but even a cylinder with some blow by will ignite as rpm's raises and run at upper rpm's. I dont think this is a "hardware" problem, apart from possibility of a lost or bent reed. A guy here had a bolt resting against a set of reed causing a cylinder to not run at all. Thats the reason I would like to know what the plugt looked like if you kill it after running WOT and take a look at the plugs right after.

 

[ezeke]

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

If you want to use my test prop, you are welcome.<br />It is part # 315983.]

 

[Goodoleboy]

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

Ya know what....I dont think alden wants to find out whats the problem...He just wants to type about it.<br /><br />Alden.....Tell ya whut...If at sucker was mine...Id damn shore and fur surtin....Get it to run 5800 t0 6000 Rs...!<br /><br />I can do it to...I aint quessin about it either...If its machanicaly sound...Ill damn well garanteen ya. <br /><br />Now stop typin back at us with another question...do sumpin dam it...Grin!<br /><br />Good luck!

 

[Goodoleboy]

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

Alden...I would like to appoligse for that post. I was a comletly out of line, and Iam sorry for it this morning.<br /><br />Little to much Christmas cheer, and it aint even Christmas yet.<br /><br />yours truly!...El Stupio!

 

[alden135]

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

OK now time to answer:<br /><br />Walker- QL77JC4 @ .030<br /><br />GDANE- The RPMS did go up. I seem to remember about 1000k. I'll check the plugs again. I have done it after wot but I'll do it again.<br /><br />ezeke- That was a very kind offer, thanks. I'll shoot you an email.<br /><br />Goodoleboy- My skin isn't that thin. Besides, it takes me so long to decifer your hillbilly english that I could'nt be offended by the time I get through it. I appreciate all your help. I just have to ask all my questions ahead of time as the boat is 100 miles away on a mooring and I only get there on the weekends.

 

[zuup_2000]

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

Im not an outboard guru by any means, just rebuilt a couple here and there. I have had plenty of experience on automobile engines and I figured Id mention something to help find an airleak.<br /> Ive always used brake cleaner (spray can) to locate a vac/air leak on automotive engines. Ive also done it on smaller 2 strokes, and it worked, so I figured Id mention it. The nice thing is that it evaporates instantly, so you wont have a huge mess to worry about. While the motor is running, just shoot it at suspected areas, and see if the idle jumps up. It may not work in your situation, but I figured Id throw it out there.

 

[MCM]

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

Yea! I used to use starting fluid as well, Haven't had to try it for quite awhile, kinda forgot about it.<br /><br />Mike

 

[sangerwaker]

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

Propane torch works even better. Just don't light it.<br /><br />alden, check with a dealer, but I believe you should be running QL78YC plugs. There was an update many years ago on this, and your manual may not be up to date.

 

[alden135]

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

Originally posted by sangerwaker:<br /> Propane torch works even better. Just don't light it.<br /><br />alden, check with a dealer, but I believe you should be running QL78YC plugs. There was an update many years ago on this, and your manual may not be up to date.

I don't have my manual in front of me but I think that was listed as the optional plug. The Champion web site lists that as the commercial plug. The first choice is a champion 5939, but I don't know what that translates to as they don't say. Could the plugs make that much difference? If so why?