Rebuilt 1996 Johnson 225 Looper Idle and Bog Issues

[jreddic4]

As an update the motor is back together with a new maxrules fuel pump installed. I started it up yesterday and it is running about the same as it has been with not idling well and needing to bump the choke to keep running or when trying to throttle up. I only idled around for fear of burning a piston out again. I noticed cylinder 2's carb was spitting fuel, which i assume is a reed issue, but swear i inspected them during the rebuild and they were fine, but will reinspect unless someone has a different idea here. Checked compression and 120 on 1-5 and 110 on cylinder 6. I am thinking my issue could be warped carbs, i do see the carb bodies definitely have some warping on the side plate where the idle circuits are, but thought the gasket was thick enough to seal them ideas to test and what should i do if in fact warped as far as replacement? I also want to verify a couple of hose connections on the recirculation fittings. I have the nipple on the upper intake manifold capped, but needed to confirm where the bottom one should be connected. I have it connected to the bottom of the air silencer. Next the very bottom recirc fitting that would be the lower bearing i have connected back to the top bearing fitting with the one way check valve in that line. Next, just above the very bottom bearing fitting is another recirc fitting that i have the hose running into the top of the air silencer. I can't find a diagram on this anywhere and lost track on original rebuild of what went where. Final Question, is for ChampioNman in that do you still have a shop in SC i can bring this thing to as i really don't want to burn it up again but feel like i need a mechanic that knows this motor to troubleshoot at this point.

[Simply_M]

The hose just ran to the airbox would be an air leak causing the lean condition. Don’t know the correct layout though.

[ChampioNman]

As an update the motor is back together with a new maxrules fuel pump installed. I started it up yesterday and it is running about the same as it has been with not idling well and needing to bump the choke to keep running or when trying to throttle up. I only idled around for fear of burning a piston out again. I noticed cylinder 2's carb was spitting fuel, which i assume is a reed issue, but swear i inspected them during the rebuild and they were fine, but will reinspect unless someone has a different idea here. Checked compression and 120 on 1-5 and 110 on cylinder 6. I am thinking my issue could be warped carbs, i do see the carb bodies definitely have some warping on the side plate where the idle circuits are, but thought the gasket was thick enough to seal them ideas to test and what should i do if in fact warped as far as replacement? I also want to verify a couple of hose connections on the recirculation fittings. I have the nipple on the upper intake manifold capped, but needed to confirm where the bottom one should be connected. I have it connected to the bottom of the air silencer. Next the very bottom recirc fitting that would be the lower bearing i have connected back to the top bearing fitting with the one way check valve in that line. Next, just above the very bottom bearing fitting is another recirc fitting that i have the hose running into the top of the air silencer. I can't find a diagram on this anywhere and lost track on original rebuild of what went where. Final Question, is for ChampioNman in that do you still have a shop in SC i can bring this thing to as i really don't want to burn it up again but feel like i need a mechanic that knows this motor to troubleshoot at this point.

I have moved to the big bend area of FL.

[jreddic4]

Does anyone know where the hose connected to the lower nipple of the intake manifold should go if not the bottom of the air silencer box?

[ChampioNman]

Yes the lower hose from the intake attaches to the bottom nipple on the air box.

[jreddic4]

Thanks, any suggestion on testing if the warped carb is causing an air leak and what to do if it is?

[jreddic4]

I have finally found what i think my issue has been. Upon a much closer inspection of the idle circuit of the carb with the metal side plate and gasket removed i found that all 6 of my carbs have a hairline crack. I put the side plate back on and plugged the front and back air intake hole and fuel/air exit to the throttle plate and blew into the fuel pickup straw and that crack let air out enough that i can nearly blow freely through the straw. I have ordered a set of used carbs on ebay that look to be in good condition, fingers crossed this will fix all my problems, update to come

[jreddic4]

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[jreddic4]

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[jreddic4]

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[jreddic4]

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[jreddic4]

Maybe these pics will help someone else if they are having issues. The crack is really hard to see until you remove the side plate and even then I thought it was a casting mark, but it’s definitely a crack where it is sucking air.

[jreddic4]

Ok, new set of used fully rebuilt with pen kit carbs installed. Motor has never ran this good, but it is still spitting out of carb 2. It was doing this prior to the carb replacement, so I pulled the intake and checked everything and reeds were great gaskets were good. Help I just can’t get this thing tuned in correctly, but feel like it is finally so close.

[jreddic4]

Typo above - OEM carb kit not pen. I think it might be leaking water around the head gasket into cylinder 2. I did put a different used head on this last rebuild just to change from prior rebuild since I kept having issues. I noticed a little drip of water coming out of the head around a bolt that I tightened a bit more and it stopped dripping on the initial run a couple weeks ago. Could water leaking in cause this? I can swap back to the original head to test my theory or is there another way to test?

[ChampioNman]

Water will not compress and any entering the combustion chamber should steam clean the piston crown and plug.

[Simply_M]

I had a similar issue with one carb lean at idle. The brass tube going down into the bowl was blocked. I was able to catch this by spraying fuel into the carbs individually and when I got to the problem carb, the motor would run smoother for a few seconds and then start sneezing back through the carb. Done while motor was in a test tank for more realistic results.

[jreddic4]

I pulled the head tonight and it’s hard to tell if it was leaking. Barely anytime on this rebuild to tell if that cylinder is cleaner than the others but I think it did look a little cleaner. The silicone outline on the block side of the gasket didn’t look to be in good shape after removing so ordered a new one and will swap the head next week when I get it back. What else could cause this issue, it’s not the carbs or the reeds, I feel really confident of that at this point. I meticulously inspected and cleaned the carbs and it was doing the same thing a week ago with the old carbs on the same piston so it is something else, maybe it was the head but didn’t see anything that obviously led me there.

[ChampioNman]

Did you put a straight edge on the head or have the head trued at a machine shop prior to installation?

[jreddic4]

I did put a straight edge on it and checked with feeler gauge. I had one spot near cylinder 2 where a bolt hole went through was at the limit. My old head is within spec though, so I will go back to it. I honestly swapped from desperation if not knowing what else to do before, but clearly my original problem was the carbs, this spitting back from carb 2 is new to this motor rebuild though.

[ChampioNman]

Wondering if you picked up an open deck head and not a closed deck head there is a difference.