2-1/2 turns or 5 turns.....low speed adjustiment. '95 OceanRunner 225.

[btravlin2]

My shop manual says start with 2-1/2 turns, but others have said 5. That's quite a discrepancy. Can anyone nail this down?

After changing filters, replacing fuel lines, rebuilding carbs, checking the pulse limiter, new plugs, fogging cyclinders, etc., I finally woke up this motor after 2 years asleep. I took it out and it runs perfect at 1000 rpms and up, but it doesn't like idle much.

I did circles at 800rpms while trying to adjust the slow speed idle screws, beginning at 5 turns. My ear couldn't detect any differences going 1 full turn either way on any of the carbs, so I decided I'd better come here for help.

I'm inclined to try 2-1/2 turns and see if that smoothes it out. Any suggestions?

 

[multimech]

Re: 2-1/2 turns or 5 turns.....low speed adjustiment. '95 OceanRunner 225.

There is more to it than simply getting the right turns out.

Make sure throttle plates are closed. The idle timing is where it should be (about 4 to 6 ATDC) All six cylinders have spark. Compression is good. The throttle bodies idle passages are clean (this is missed by a lot of people and it is important.)

Most of these engines that I have worked on have a starting turns out of 5 3/4 turns out from seat. A trick is to have the engine in the water at it's normal height. When you have the initial turns out, flick the throttle without moving the spark advance linkage. Does it snap and then come back to idle smoothly? If not turn it a bit leaner if it lags on the "snap" if it dies on the "snap" bring it out more rich.

I don't know what the turns out on your engine are, it shouldn't be hard to find the place where they begin to respond. It is either 2 1/2 or 5 3/4 if the carbs are clean and the throttle bodies are clean. You will be able to find the intial turns out pretty easily. Any one or more of the cylinders blocked at idle will mess up your results. First take the spark plug lead off each cylinder with a load on the engine and see if it "hits" or not. That will help you immensely. When you determine they all "hit" then start moving out each carb needle in 1/8 of a turn out or in until you dial it in.

Another thing that will screw up your adjustments is a piece of crap from a rag, or junk that gets into the carb after your rebuilding them. I have taken carbs off more than one engine and gone through them again when I found that I could not get all cylinders to "hit" at initial adjustment. It happens.

Good luck

 

[daselbee]

Re: 2-1/2 turns or 5 turns.....low speed adjustiment. '95 OceanRunner 225.

Multi nails it. I will add that on that particular engine, it is 5 1/2 turns out, not the questioned 2.

 

[glenn property of pam]

Re: 2-1/2 turns or 5 turns.....low speed adjustiment. '95 OceanRunner 225.

doesn't the manual say start at 2-1/2 turns, not set to 2-1/2 turns. Most of the experts who's post I have read will tell you that they end up near the 5 turns so they seem to skip the 2-1/2 starting point and just go straight to 5 turns then adjust from there.

 

[daselbee]

Re: 2-1/2 turns or 5 turns.....low speed adjustiment. '95 OceanRunner 225.

There is a model (it is not the '95) that has an idle adjustment screw that meters AIR instead of gas. I think it was 93 or so. OMC was having real trouble getting the carbs right on these loopers. They changed almost every year until '95 - '96 and then they stayed the same til 2001....But anyway, the adj screw he has is metering gas thru the circuit to adjust final mix for idle. Those screws are set at 5 1/2 turns out. The design where the screw meters air is set at 2 1/2 turns out initially. His screw is at approx. the 8 o'clock position, and the air metering design has the screw at just off 12 o'clock position...maybe 1 o'clock. I forget the exact placement. That is why the confusion on the 2 1/2 vs 5 1/2 turns out initial setting occurs. Also, OP, you will not really see much difference in turning those screws. Too far in, the engine will begin to lean sneeze, too far out, and it will drip unburned fuel oil mix from the prop after idling for an extended period of time. To get it exact takes time and patience, and multi has a great method with the "flicking the throttle" technique. You will need to keep adjusting the screws, checking idle speed and adjusting if needed, and then adjust the mixture screws again if needed. It is tedious, if done right.

 

[btravlin2]

Re: 2-1/2 turns or 5 turns.....low speed adjustiment. '95 OceanRunner 225.

Thanks for the detailed reply. I just tried 2-1/2 turns and that definitely didn't work. My manual is off on that one. I'm clearly in the 5+ range.

I trust my carb rebuilds, at the very least because the previous owner said the motor didn't idle well in the past. My rebuilds didn't change anything. So I think I'm good there. I'll check timing. And wouldn't it be the case that if spark were bad the motor wouldn't sing at anything above 1000rpms, which it does?

And lastly, I don't think I understand how to adjust 6 carbs. A single automotive carb is easy.....you can hear it so clearly. But how do you differentiate the sound of one carb from 5 others? I mean, if it were idling smooth to begin with, it would be easy to hear any one carb acting up. But when they all might be off alittle, how do you tell when you've got one right?

Before I do anything else I'm thinking of a decarb with Seafoam. Man, that stuff has gotten pricey!

 

[Faztbullet]

Re: 2-1/2 turns or 5 turns.....low speed adjustiment. '95 OceanRunner 225.

OEM manual states 5 turns to start off with and must be in water,in gear, untethered to adjust. Start at #5 & 6 and work your way up to #1.

 

[daselbee]

Re: 2-1/2 turns or 5 turns.....low speed adjustiment. '95 OceanRunner 225.

I have preached this til I am blue in the face....you gotta make sure the throttle bodies are clean. People think if they clean the black plastic carbs they are done. Nope. The idle fuel circuit is largely contained within the throttle bodies. Just look at it...that idle mix screw threads into the throttle body, not the black plastic carb. Behind the metal plate held on with four small Phillips screws are very tiny holes that pass fuel thru the venturi sidewall. Those holes have to be clean. secondly, there is a small brass tube that extends down into the fuel bowl. That is the fuel pickup for the idle circuit. That has to be clean. don't be fooled. The tube tapers to a small opening at the top. It is not the same diameter as it is at the bottom. I blow thru and suck thru with my tongue feeling the air flow. It is a good way to judge if you have the upper part of that tube clear. Serious. Thirdly, all butterflies must be absolutely closed. None of this "that's close enough" stuff. Closed. The main culprits of being slightly open are #5 and #6 due to the adjustment between the upper throttle body and lower throttle body. I always adjust/set these throttle plates for full closure and complete synchronization with the black carb bodies OFF. You can see the whole mechanism so much better.

 

[btravlin2]

Re: 2-1/2 turns or 5 turns.....low speed adjustiment. '95 OceanRunner 225.

I have preached this til I am blue in the face....you gotta make sure the throttle bodies are clean. People think if they clean the black plastic carbs they are done. Nope. The idle fuel circuit is largely contained within the throttle bodies. Just look at it...that idle mix screw threads into the throttle body, not the black plastic carb. Behind the metal plate held on with four small Phillips screws are very tiny holes that pass fuel thru the venturi sidewall. Those holes have to be clean. secondly, there is a small brass tube that extends down into the fuel bowl. That is the fuel pickup for the idle circuit. That has to be clean. don't be fooled. The tube tapers to a small opening at the top. It is not the same diameter as it is at the bottom. I blow thru and suck thru with my tongue feeling the air flow. It is a good way to judge if you have the upper part of that tube clear. Serious. Thirdly, all butterflies must be absolutely closed. None of this "that's close enough" stuff. Closed. The main culprits of being slightly open are #5 and #6 due to the adjustment between the upper throttle body and lower throttle body. I always adjust/set these throttle plates for full closure and complete synchronization with the black carb bodies OFF. You can see the whole mechanism so much better.

When I rebuilt the carbs I meant the throttle bodies as well (why would anyone just do the black part?). I know the tiny holes you're talking about, and the tube. They were all blown out with carb cleaner, iso alcohol, and air.......as the manual says. So I think I'm good there.

The throttle plates are fully closed.

I had the SS screws set at 5 turns. Multimech suggests 5-3/4, so that's what I'll try next, and go from there.

 

[btravlin2]

Update: 2-1/2 turns or 5 turns.....low speed adjustiment. '95 OceanRunner 225.

Update: 2-1/2 turns or 5 turns.....low speed adjustiment. '95 OceanRunner 225.

I've got time this weekend to take it out again. In preparation, I adjusted the carbs out to 5-3/4 turns and put it on the muffs. Now it stays idling and the idle speed went up, as opposed to before, but it's still alittle jumpy.

My question: do I tweak all carbs the same amount at the same time (ie: 1/8 turn), or is it just one carb at a time?

 

[hall832]

Re: Update: 2-1/2 turns or 5 turns.....low speed adjustiment. '95 OceanRunner 225.

Re: Update: 2-1/2 turns or 5 turns.....low speed adjustiment. '95 OceanRunner 225.

First take the spark plug lead off each cylinder with a load on the engine and see if it "hits" or not. That will help you immensely. When you determine they all "hit" then start moving out each carb needle in 1/8 of a turn out or in until you dial it in.

Multi gave easy instructions.

 

[pn]

Re: 2-1/2 turns or 5 turns.....low speed adjustiment. '95 OceanRunner 225.

i like seafoam. if you haven't done so yet.

 

[seahorse5]

Re: 2-1/2 turns or 5 turns.....low speed adjustiment. '95 OceanRunner 225.

A 225 in a good state of tune and engine condition operates better at about 6 turns open on the idle mixture screw. Make sure the thermostats allow the motor to warm up both cylinderheads above 130? and that the carbs are clean and the sync and link is adjusted per the service manual.

 

[c6mcfall]

Re: 2-1/2 turns or 5 turns.....low speed adjustiment. '95 OceanRunner 225.

I have to ask, when Multi states "When you determine they all "hit" then start moving out each carb needle in 1/8 of a turn out or in until you dial it in".. Can you tell me what you mean by hit? Just want to make sure I'm following this correctly.