Jump to content
Sign in to follow this  
Ski213

Carb Adjustment Question

Recommended Posts

When I bought my boat there were some fuel issues. Got the largest part of that ironed out a year ago but fixing the big issue created a small one, depending on your definition of small. It's a 97 johnson 225. In the morning it fires up and you're gone as soon as you hit the hot foot. After it's been run and you've fished and you're ready to move it wants to die when you hit the hotfoot. After varying amounts of idling and priming it will get on out of the hole and it's fine. Heatsoak was mentioned to me and that's prob it but I want to mess with the low speed adjustment some. I'm used to one carb on a motocross bike, not six. So my question is when adjusting do you adjust equally across all cylinders? Say 1/4 turn on all six? Or is that too much at a time on one of these?

Share this post


Link to post
Share on other sites

Actually for starters, I think you screw all six low speed in all the way, then back them out 5 1/2 turns. The 97 has fuel controlled idles so you go clockwise to lean and CCW for rich.

Do not try adjusting the mixture (beyond the initial setting) or idle speed on a hose. The motor has to be in the water and should be trimmed level. The water creates a back pressure and without it you will never get them set right. Normally the initial setting is pretty good.

Share this post


Link to post
Share on other sites

The only reliable way to do this is to use a carb synchronizer tool. It measures the vacuum that each carb is pulling, so you can be certain that they are all adjusted the same. They need to be very close all the way from idle to WOT. 

 

You can make your own synchronizer with some bottles, hose and ATF (auto trans fluid, that is; and a few other odds and ends.) A good carb synchronizer will probably cost you less than taking it to a shop, however. There are countless articles/videos online showing how to do this procedure, for both land vehicles and marine. 

 

Take your time, and do the research for your carbs/OB. It's not too difficult of a job, just tedious. 

Share this post


Link to post
Share on other sites

Alright. I appreciate the advice. I've got conflicting info on initial settings. I think it's a typo in the service manual (seloc manual) so not the true service manual. There's overlap in the year models. My assumption is that at 96 it should've gone from 2.5 turns to 5. I haven't checked all six but 2,4,&6 were all different. Ranging from 6.5 out to 4.5 out. 2 was the fattest. Maybe the last guy did that to keep it cooler as 2 seems to be problematic on these. Cooling mod was supposedly done but I don't guess I can verify that with the engine intact.

I'm definitely going to check out the carb syncing deal. Again i appreciate the responses.

Share this post


Link to post
Share on other sites

A couple of things you need to be aware of. 96 and later carbs are fuel control idle, 92-95 are air control idle so make sure you use the right manual. The adjustments are 180 degrees opposite.

A proper Linc and sinc is critical but due to the design, trying to use a carb sync gauge set is not very practical. I've been messing with these motors for a while now, and while I have a sync guageset I've used numerous times on automobile engines, but not here. I've even tried dial indicators on them and I've found that just taking your time and watching the butterflies movement.

Share this post


Link to post
Share on other sites

I think I get what you're saying. 96 and later I'm metering fuel so backing the needle out I'm allowing more fuel vs pre 96 where backing it out allows more air so leaning her out?

I think I'm as solid as I can be with my on the linc and sync given my limited experience with outboards. I'm going to set everything back to factory settings and see what that does I guess.

Given your experience with these motors would you say that i'm experiencing heatsoak? If so is it best just to deal with it or should I take the time to try to tune it out of it?

Share this post


Link to post
Share on other sites

I've never had but one motor that I had the heat soak issue with.  It was 90 open deck block I had modified to about 310 hp and that was back when I first started playing with the 3.0's.  Why a particular motor will do it and a whole bunch others don't, I don't know, but I'm not sure there is a cure for one that does.  Usually, pressing the primer two or three times after starting it will take care of it.  That one motor did it until I quit using it, actually until it stuck a piston, the end of the rod came through the bock and tried to saw itself in half.

 

Normally, heat soak is an issue after running hard to a spot, killing the motor, fish for a 1/2 hour or so and then try to blast back out of there, and it will not take fuel without dying.

 

Now, carbs that are too lean on the idles act almost the same way.   Just triple check you setup.  Look at the butterflies and make sure all six are fully closing and all start to lift at the same time.  It's very common for me to find the two bottom carbs out of sinc because they are separate from the upper carbs.  They have to be by that bent piece of metal connecting them.  One end of it loosens and lets you sinc the bottom carb with the upper ones.  Then make sure the port and starboard sides all start to open at the same time, that's adjusted by the rod connected between them.  Next get all the marks on the linkage setting exactly where they are suppose to be, then you adjust the cam roller so it hits right on the mark.  Make sure the roller still has the clear sleeve over it and not just the black part is stick up.  The roller should be about 3/8" in diameter.

 

Now, once you get all the linkage adjusted properly, DO NOT adjust the idle by stops on the linkage.  It's adjusted by the rod on top going back to the timer base, by turning it so it moves the timer base.  If you try to use the linkage stops, it throws all those adjustments you just spent over an hour making off.

 

With this crappy gas, I would back my timing down to 16 degrees also.  There is a trick I use to get me close on timing but it has to be set with the motor under power and turning over 5,000 rpm to be set right.  You can take the cam roller off so it doesn't open the butterflies and then go full throttle.  The engine will only rev to about 2,000 rpm and will be at full timing, but the reading you get on the lite doing this needs to be set about two degrees low, 14 degrees since you want to shoot for 16 when done.

 

Now, to set it right, under full power without ridding down the lake at over 60 while hanging over the back of the boat.  Take someone with you to the lake, Leave the boat strapped to the trailer, back the boat into the water so the anti-cab plate is level with and about three inches above the water.  Make sure there are no boats for a couple hundred feet behind you.  Start it up, watch the tach put it in forward gear and go full throttle for a few seconds.  Tach needs to read at least 5,200 rpm and no more than 6,000.  If it's too low, pull the boat out so the motor is up another inch and try it again.  If the rpm is too high, back it in more so it's another inch lower. This will be blasting one hellava wall of water out behind the boat.  When you get it right, connect the timing light and check your timing.  Only run it like this a few seconds, just long enough to get a reading, make any adjustment at idle and try it again.  One person to do the gas while one is doing the timing is the reason for the second person. 

 

If you have a dinged up spare prop, it might pay you to put it on also.  That motor is going to be moving a lot of water and will pick up any small rocks etc and they can ding your prop.

Share this post


Link to post
Share on other sites

Forgot to mention, apparently you have read about the unbalanced cooling these motor have and how #2 is subject to loose a ring locator pin and wipe out the cylinder. 

 

Fattening up the idles does nothing for preventing that.  A bandaid to help minimize this is to increase the main jet in #2 carb by one size.  It should have a #72D so go to a #73D.  This problem actually pertains to #2, 4, and 6.  It's just #2 runs the hottest (about 50 degrees hotter) of the three so it's usually the first to go, but sometimes #4 goes first.  I do a cooling mod on my motors that balances the cooling and eliminates this problem, but this mod has to have the powerhead off and the heads off to do it. 

 

You can do random inspections of the cylinder walls on #2 and #4 and if you catch it early, it can save a grenaded cylinder.  When the pin starts backing out, it will start making a small scratch mark in the cylinder wall that goes through the middle of the transfer port.  The scratch mark soon turns into a gouge and the pin eventually hangs the lip of the transfer port, breaking the sleeve and the piston, and hopefully it's at lower rpm so it doesn't destroy the block.  The best way I've found to inspect the cylinder is to solder the wires from a small cell phone charging cord onto a small dash lite that has to wire terminals.  Clip one end to ground and the other end on the starter solenoid.  With that bulb inside the cylinder, it lights it up like daylight and you can see very easily.

 

I've seen these motors run 1,000 hours with no problem, and I've seen them grenade in less than 300 hours.

 

Why they had to put the pin going through the center of a port is beyond me, but they did.  Wisco moved it so it doesn't pass through a port on their replacements. 

Share this post


Link to post
Share on other sites

I'm checking the carb sync right now. Went through and set all the screws back to 5 out. Just going to work back through all of it. Yeah you're right fattening the idle circuit would do nothing at 6000rpm I guess. I can't remember what the mains are. I checked them last year and I do remember them all being the same.

This engine was a victim of the pin issue before I bought the boat. Supposedly the cooling mod was done as well as something for the pin issue. Maybe going with the wiseco. Previous owner had the work done. I've known him and im sure he told me what his mechanic told him but unfortantely I dont have a whole lot of trust in alot of shops.

Shot the head with a ir thermometer awhile back and there was definitely some deviation at idle. Checked the stats on both banks and they seemed to be fine. I checked after running once and they were +/- 5 degrees. But now that I think about it there very well could have been enough down time for it to all balance out before I checked it.

You helped me out a ton last year with the original issue I had. That dash bulb trick is slick. I was using it then to check out where I was as far as rich/lean and I also took a look at the cylinder wall since I had a cylinder not fueling right to see what the damage was. Could still see the hash marks from the honing but could also tell there was a touch more wear. Haven't looked in there in awhile though so ill definitely keep an eye on it.

Share this post


Link to post
Share on other sites

I would start with 5 1/2 turns. At your elevation, that's should be pretty dang close, probably won't have to touch them again. However, sinc is critical, so get all six where the butterflies fully close and all start to open together. It's a pain in the *** but again, very critical.

The cooling might be a maybe. A few mechanics and shops know of it, but very few actually know how to do it. They call themselves doing it, but there is one a hidden step that not many know of and it's one of the more critical parts of the mod. The purpose of the mod it to reroute the water though the motor. I normally comes up from the bottom, washes up trough the water jackets and out the TStat at the top. So, you have cold water coming in the bottom and hot water going out the top. The mod brings it in the top, down one side of the cylinders, around the bottom and back up the other side and out the TStats. What happened, some have seen the mod on blocks and they see the hole drilled to let the water come in the top, and all the baffles added to route it and though that was it and the word got out that's how it's done. What they didn't see is where the original factory holes in the bottom drilled, tapped and plugged up inside the exhaust chest. So most end up with half a mod that's not as effective.

Share this post


Link to post
Share on other sites

If you ever have the head off, it's very easy to check for the cooling mod.  I can send you pics of what to look for.   Not  too sure how comfortable you are with working on these things but popping a head off is a piece cake.  I do it all the time and since it's not that old, I reuse the head gasket three or four times. Provided someone idiot didn't stick some kind of sealant on it.

Share this post


Link to post
Share on other sites

So correctly done you're actually re routing the cooling water. Half ***ed you're I guess you're helping some but you're not routing the water as much as just giving a little of it a chance to get up top earlier? Cool to hear what the cooling mod is actually intended to do versus just hearing the cooling mod is done.

I'd sure appreciate the pics. I'm not a marine mechanic by any stretch of the imagination. I've banged around on this and that. I'm not ever super comfortable tearing into something that I have limited experience with but that's never stopped me in the past. Probably be worth the work to know where this engine stands as far as what has and has not been done properly. Even if its wrong I'd rather know than wonder. I appreciate your time once again.

Share this post


Link to post
Share on other sites

You will have to pm me your email.  There is too much to post on here

 

Yes, you are completely changing the way the water flows through the motor.  My friend that developed this mod gave it to OMC back in 1995 but it was not until the 3.3 blocks went into production they incorporated it.   He was a racer and factory back by OMC and they constantly came to him for inputs on their motors.

Share this post


Link to post
Share on other sites

You will have to pm me your email.  There is too much to post on here

It won't let me PM you. Email is adamg0794@hotmail.com

Thanks

Share this post


Link to post
Share on other sites

OK, I hope it finally went through. This junk I have for internet hasn't let me do much lately but you should have an 8mb email in your inbox.

Share this post


Link to post
Share on other sites

Well it's been awhile since this was originally posted but it's taken that long to get a situation where I could really hold WOT long enough to see if it's fixed. I can't swear to it yet but I'm pretty sure it is. I figure the fuel screw adjustment did it. 5 1/2 turns out as suggested. It was either that or doing the linc and sync again, or something that I inadvertently did when I pulled the head to check the cooling mod. I'm guessing the screws.

I once again appreciate the help. The only bad part is that if this part is fixed I'll have to start messing with with p shaft height and maybe prop to see what she really likes. Gotta have something to keep you busy I guess.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Sign in to follow this  

  • Recently Browsing   0 members

    No registered users viewing this page.

  • fishing forum

    fishing

    fishing forum

    fishing rods

    fishing poles

    fishing

    fishing reels

    fishing poles

    fishing poles

    fishing

    fishing

    bass fish

    fish for bass
    fish

×
×
  • Create New...