1985 Honda B100, possible air leak?

[Tarinazo]

Hello, I have a new-to-me mid 80's Honda B100L that was used on saltwater, before starting it for the first time in my test tank, I cleaned it up real good: carb, thermostat, impeller, manifold, hoses, fuel pump. It had lots of sand and flaky residue in the internal... the cleanup helped a lot.
Before having it all back together, I had to make a manifold and carb gasket because the one's on it ripped while taking those parts out. For the manifold, there are two gaskets, the one that has contact with the engine block was intact, so I left that on there, but the one I had to make is the one that makes direct contact with the manifold... I had to make them because it's hard to get OEM parts here in Mexico where live. I used a gray asbestos free gasket material bought at an auto repair shop, 1/16 thick.
So once I had the parts back together and it was time to start the engine for the first time... for me, choke on, first pull and the engine started immediatly and idled perfectly, I couldn't believe it.
The bad news started as soon as I took the choke off... it revved at high RPM's and then shut down. It took me 3 or 4 pulls to start it this time with the choke out, once again purred perfectly but as soon as i puched the choke same thing would happen.

I'm suspecting an air leak in those gaskets I made, I'll do the "ether spray" thing to find those air leaks as soon as I get the engine on the working bench again (right now I'm struggling with a 6hp Merc, made a post also).

Also, I had this Honda engine running for about 10 minutes most and the water in the test tank turned out gray with heavy black oil on the tank's walls... what could this be?

 

[Mohawkmtrs]

Choke rod interfering with the throttle rod/throttle mechanism?

You say the motor is new-to-you...the sludge in the test tank may just be residue from cleaning everything up or who knows how the engine was ran/treated before you got it.

Once you get the choke/high revving issue is resolved, take it for a good long, hard ride to "stretch its legs"...chances are everything will clear up.

 

[Tarinazo]

The rods from the throttle and choke don't interfere with each other, I double checked that.

If I move the throttle rod a little bit while in neutral, to rev the engine up, it has sort of a delayed idle... something like this:
Pull on rod, 2 seconds later it revs at high RPM's for some 3 seconds then it bogs down and shut off.
I can do this multiple times and not let the engine shut down reving it, but I have no control of the idle, it's either revving or dead.

 

[racerone]

I doubt that it is an air leak.-----You need to look at tiny passage ways in the carburetor !-----Bought 2 motors like that from one owner.-----said " can not find a shop that knows how to fix them "-----Had both idling nicely after cleaning the carburetors.----On more than one occasion have we seen folks struggle and finally after cleaning carburetor for the 3rd time did they have success.

 

[Tarinazo]

Yeah, I've read just about every forum on the subject and it almost always comes back to the carburetor. I did an air leak test yesterday and no surprise: gaskets are good around manifold and carb, so I will focus on the carb cleaning today. Carb question: when removing the main jet I can see the brass hole/tube that goes upwards to the carb is clean (directing a ligt into the carb I can see this), but I also see at the side of that brass tube, where the threads ends, two small holes facing eac other, are those passage ways also? they seem hard to get with the crab straw or even a small copper wire. Another question, on the butterfly position: when the butterfly sets all the way on closing position, there are two tiny (very tiny) holes on the side. does the butterfly sets between this holes? or does the butterfly suppose to rest/seat passing both holes? I hope I made myself clear explaining this, I sometimes forget my english.

 

[Tarinazo]

SOLVED! sure enough it was a carb issue. The first time I cleaned the carb I did a great job at it, except for the inner tube in the main jet, wich I didn't knew that the piece could come off, it was stuck in place with crud. Some WD-40 bursts and heating the carb with a hair dryer did the trick.
Once the carb was clean again, really clean this time, the engine started on the first pull with choke activated. Let the engine warm a few minutes, pushed the choke lever in and it idled with no hesitation, just a few dialing moves on the idle and mixture screw (2-1/4 turns out on the mixture) and the engine kept purring with no problems.
I let it run like that for some 10 minutes, it got really hot but it never turned itself off, I hope this is normal operating temperature.

 

[Mohawkmtrs]

May have gotten hotter than normal because being in a tank with water heating up from engine exhaust.

Put it on the back of a boat and take it for a run and perform the final adjustments on the carb.

Water coming out the tell-tale?

You should be able to put your hand on the cylinders/head for a 3 count without burning your hand.

 

[Tarinazo]

I'll take the jonboat for a spin this Sunday for the carbs final adjustments.
Plenty of water peeing out constantly.
Not sure about the 3 second "rule" the water coming out from the telltale isn't hot at all, so the water in the tank remains fairly cold all the time the engine is on.

 

[Mohawkmtrs]

Water coming out of tell-tale is water directly from water pump...it is only an indication that the W/P is working and does not circulate through the engine so the water at the tell-tale should not be hot.

The majority of the water from the pump circulates through the engine absorbing heat and is exhausted through the prop thus having the capability of heating the tank water.

For the three-count rule: try it on the water...if the engine is not over-heating you will be convinced.

 

[pvanv]

Use an IR thermometer to see what the actual temperature of the motor is. Should be maybe 150F. If over 180, you are not cooling properly.

 

[Tarinazo]

Thanks for the reply PVANV, but I never got to use the B100... traded it for a B75 in much better conditions, I'll open a new thread because I have a few questions about the B75's speed.