Help with my Johnson 25 RLCUR Frankenmotor.

[w2much]

This thing has a history of running bad, spitting, stalling running good at high speed then stalling. I saw an old bulletin regarding this on the Tube but it did not help. I rebuilt the carb, then again maybe even three times. After all that I realize its an air leak somewhere. Sprayed WD, starter fluid ect around the manifold, the crankcase seam, the carburetor to no avail. The manifold has been changed out at one time so I went into the leaf valves for a look. I thought air might be getting into the manual primer. I knew something just did not know what. I have a manual for the motor but it only refers to replacing hoses where they were before disassembly. On this motor there is an air recirculation or oil or fuel recirculation nipple on the #74 bypass cover. It is in such a place that I never saw it. It is behind the fuel pump and it was plugged with a chingadero and some grease. I figure this is my problem but am curious whether to once again plug it or was there a missing hose that should be there . The nipple is about the same size as the small nipple on the manual primer.
Issue #2 . The hose nipple on the actual manifold bottom left is plugged off also. It is for a much larger hose than the bypass nipple. What hose goes from the manifold to where ? My primer parts diagram shows the feed hose with a T in it. Big hose from carb to primer, one hose out of primer to a T where are hoses supposed to goe. One goes to the top of the carb, there is a small nipple there. Where does the other one go. ? I realize it is a Frankenmotor and I can experiment with lots of time and hoses but if fuel (oil) is not going where it is supposed to go even if I get it runnung great it may not be long before it has a seizure. I have both an OMC and a Clymer manual for this motor but not a Dr. Franken manual..If any one can decipher what I am saying all replies are welcome. Racerone you can not tell me to get the manual this time
Thanks, I will look for an answer in the morning and post or clarify any questions or digs.

some grease.

 

[flyingscott]

One primer hose goes to the carb. One goes to the intake for sure. You may have a 3rd one that goes to the top transfer port.

 

[Newyota]

Did someone put a 30/35hp intake on it?Should be a part number on the intake. I know my 20hp to 25hp conversion had the the same nipple size. I think a 35hp has the larger nipple. I have a 30hp intake that has the same nipple as the 25hp.

 

[w2much]

I will check on parts numbers and cross reference them to other motors. I have a 35 hp to check its manifold nipple size. I should have done that already. The carb itself may also be switched. It is off and easy to verify.Nipple size aside, where would the hose on the bottom of the manifold go to ? It was going to the primer T and as such would be fed fuel upon priming. That did not make sense to me as the fuel would puddle there. Now I am thinking it should be routed to the bypass cover small nipple pictured. Then the fuel would be atomized upon induction rather than puddled inside the manifold at the large nipple on the bottom which perhaps should just be a small nipple and therein lies my answer ?

 

[Newyota]

This thing has a history of running bad, spitting, stalling running good at high speed then stalling. I saw an old bulletin regarding this on the Tube but it did not help. I rebuilt the carb, then again maybe even three times. After all that I realize its an air leak somewhere. Sprayed WD, starter fluid ect around the manifold, the crankcase seam, the carburetor to no avail. The manifold has been changed out at one time so I went into the leaf valves for a look. I thought air might be getting into the manual primer. I knew something just did not know what. I have a manual for the motor but it only refers to replacing hoses where they were before disassembly. On this motor there is an air recirculation or oil or fuel recirculation nipple on the #74 bypass cover. It is in such a place that I never saw it. It is behind the fuel pump and it was plugged with a chingadero and some grease. I figure this is my problem but am curious whether to once again plug it or was there a missing hose that should be there . The nipple is about the same size as the small nipple on the manual primer.
Issue #2 . The hose nipple on the actual manifold bottom left is plugged off also. It is for a much larger hose than the bypass nipple. What hose goes from the manifold to where ? My primer parts diagram shows the feed hose with a T in it. Big hose from carb to primer, one hose out of primer to a T where are hoses supposed to goe. One goes to the top of the carb, there is a small nipple there. Where does the other one go. ? I realize it is a Frankenmotor and I can experiment with lots of time and hoses but if fuel (oil) is not going where it is supposed to go even if I get it runnung great it may not be long before it has a seizure. I have both an OMC and a Clymer manual for this motor but not a Dr. Franken manual..If any one can decipher what I am saying all replies are welcome. Racerone you can not tell me to get the manual this time
Thanks, I will look for an answer in the morning and post or clarify any questions or digs.

some grease.

Ok.You peaked my interest about that other fitting on the bypass cover since I was sure I did not have one on my 1985 20hp motor.Your motor is an 1987 if I looked it up correctly and should be like mine.I do see the spot(on my motor) where you have that on yours and have no idea why that fitting is on your motor.I would think you would(possibly,but not sure?) suck air into your cylinders and run lean with that just open there,I am not sure where that hole goes thru the bypass cover..I had a gasket on my fuel pump that was allowing air to be sucked in and my engine was running lean.You should have one hose from the primer "T" go to the nipple at bottom of intake and one going to the Carb throat on top.Are you sure of the model #.Does the # on power head match the transom Tag?The part number for your model # motor for the bypass cover does not have that nipple behind the fuel pump so somebody put it there or you have a different power head or franken motor like you say.

 

[w2much]

I saw on newer 25 hp's the nipple is on the bottom cylinder of the bypass cover. Where it goes I do not know. With the bottom nipple on the manifold cover plugged , the T from the primer removed, one primer hose going to the nipple on the carburetor the motor ran pretty good but not good enough. I discovered the nipple on the bypass cover knowing there was an air leak somewhere. Why would a primer hose (outlet) go to the manifold nipple, correct size or not? It seems to me that the nipple on the bypass should be connected to the nipple on the bottom of the manifold to suck out puddling fuel. That is shade tree logic. I am no trained technician nor an engineer ( I' ll bet you guessed that by now ).
When my gaskets arrive I will try that hose setup.
In the meantime I need to check and cross check the existing parts numbers.

 

[flyingscott]

The primer nipples are all the same size!! Your manual primer cannot.leak air. It can.leak gas and cause a flooding problem. Have you done a link and sync? Put up a pic of the carb link where it attaches under the flywheel. Make sure the throttle is turned towards slow as far as it will go. The nipple on the intake is in front of the reed valves fuel does not puddle there.

 

[w2much]

I will be putting it back together, parts have been delayed. I guess my manifold cover was switched at one time or another. The nipple, lower left side is certainly larger. I can either use a reducer or just plug it as it starts fine with one primer hose going to the nipple on top of the carburetor. This just leaves the nipple on the bypass. I will plug that one also probably. I really think those two actions will solve the problem. My concern was what was the function of the nipple on the bypass cover. Thank you Flying Scott and Newyota, I appreciate your input. I will post on it when finished.

 

[tootallofwa]

On my rx10l 63' 28hp that hose goes to the cutout switch. looks like a pressure vent? should be a pulsating vac/pressure port. could be used for a fuel pump too...

 

[racerone]

Well a 1963 model 28 HP is a totally different set-up than the 1987 model 25 discussed in this thread.

 

[tootallofwa]

Well a 1963 model 28 HP is a totally different set-up than the 1987 model 25 discussed in this thread.

What the port is used for is completely relevant! it's a frigin 2 stroke aint it.
Totally unnecessary dis comment from racerone.

 

[racerone]

???------Not sure what you mean here.

 

[tootallofwa]

plug the port or use it for whatever pulsing vac/pressure you need.

 

[racerone]

In the picture ( post #1 ) the man has his finger on the gasket to mount the fuel pump directly over the fuel pump pulse port !

 

[tootallofwa]

So, It's not the fuel pump and ther is no cutout... How about... Overboard Pump Indicator? How it would work, is beyond me. but it needs a nipple and hose... Found it on the exploded crankcase view.

 

[tootallofwa]

or better yet #16 - Hose, solonoid to by-pass cover from the electric Primer System

 

[tootallofwa]

#24 goes to carb #25 goes to Manifold. #17 goes to primer #20 goes to carb also. I think #18 is Fuel Line from fuel pump

 

[racerone]

There is air behind that cover so it is NOT the pee indicator.

 

[w2much]

racerone is correct, definately not a pee indicater.And yes there is air behind that cover,the same vacuum pulse as the fuel pump I imagine.. But just to clarify my finger is on the fuel pump gasket but I am pointing to the nipple . I will call it the nipple to nowhere.Remember this is a Frankenmotor . I have a manual primer on this motor, not the electric primer. My carburetor does not have the fixture on the bowl to hold the electric primer. The manual primer is installed where perhaps an electrical harness was intended. There in lies some of our confusion.
Here is a quote from my Clymer manual regarding my issue.:
" Some reed blocks contain a recirculation valve hole and reed; others use a recirculation hole and screen assembly. " shows illustration pictures of each.My manifold has the recirculation reed valve. This manifold came from another corpse motor. So on this motor I do not think the nipple on the bottom left of the manifold has to do with priming. It is my thought that the nipple to nowhere should be connected to the lower manifold nipple and is part of the recirculation system. It is probably not needed because there is a drain hose going to a nipple roughly at the top crankshaft bearing down to a nipple at the bottom crankshaft bearing.Looking at the intake manifold diagram for J25 RLCUR see # 9 refered to as drain valve. To simplify the confusion I may have caused where would this #9 drain valve drain to ? Would the nipple to nowhere suck this out ?

 

[racerone]

Fuel pumps run on a PRESSURE pulse and not so much a vacuum pulse.