Hello everyone!

I have and love my '82 FL250!
I just installed a new Wiseco piston (the old one partially blew up, the previous owners must have had it running too hot!)
and I recently bought new NGK BR7ES spark plugs and a new float valve from ebay (original part & packaging!)

My question to day is...

What is the difference between the 2 spark plug positions?
One is straight vertical, the other is at an angle.

Which should I use, because my Odyssey love to burn fuel. (about 5 litres in 20 minutes!)
The fuel tank is custom now, gravity fed and has a new fuel pump as well...

Would the angled plug help fuel economy?

Thanks!
Silver_Pharaoh

There is no such thing as fuel economy with these old 2 strokers. To answer your question I believe there is no difference. the extra hole allows you to have a spare installed plug. If one fails swing the wire over to the other one. I don't do this - I just run the plug in the vertical position.

I'm a little confused that you say a gravity fed and has a new fuel pump as well... usually its one or the other. Also do you have any fuel coming out the over flow tube on the bowl? This is a indication the float valve is not sealing - shutting the flow of fuel off. Do you have a 3 way valve?


Pictures would be nice if you can post some up.

Fuel from overflow??? OH YEAH BIG TIME!!! I actually put a nut in the tube to prevent this, as it only seems to really happen when it's idling (it shakes like no tomorrow)

As for the float valve, I bought one brand new last summer from ebay. It was an original OEM part (original packaging, no tampering on the package) so I installed it and adjusted the float arm "tang" as the shop manual calls it.

As for the fuel tank, yeah my dad had one custom made from a truck exhaust stack and replaced the old diaphragm pump. both original tank and pump were full of rust.


I'll snap some pictures for you today, so I'll post them later..

Silver_Pharaoh

The 3 way valve diverts gas back to the tank - only filling the bowl when the float opens the valve.

You need to fix the overflow problem.

Sorry for the photo quality, I have yet to wash my odyssey

The first picture is the new pump my dad put in.

The second is the new fuel tank we had made for us. Note that it still has the old tubing that feeds fuel back to the tank (as shown in the third picture.)

Any help to reduce the fuel usage is appreciated, as using 5 litres in roughly 20 minutes can't be normal... =(

Thanks, Silver_Pharaoh

As rmesser mentioned, the fuel economy on these old birds just sucks. The Engine fires with every revolution so you are using approximately twice the fuel of a 4 stroke (almost twice the power though ).

As far as which spark plug hole should you use, you want to use the top spark plug hole.

The FL250's head was originally used on the Elsinore 250 and was then adapted to be used for the FL250. The angled plug hole was for use of a compression release on the Elsinore. On the Fl250 Ody, Honda decided to just plug the hole.

Rand

Thanks, Randman for the info, I'll keep using the vertical plug.

As for the too much fuel issue i'm having, what should I do?

I bought a brand new float valve & seat but when idling, the fuel just pours out the overflow!

Not sure if this has much to do with it, but the throttle slider? (I think that's what it is called) is original (33 years old) and the idle screw has made a dent in the slider. I was thinking I could just fill the dent / hole with JB weld or something, is this a good solution?


Thanks,
Silver_Pharaoh

If you are having issues with excessive Engine shake at idle you need to check the following.

1.) Engine mounts. If your Engine mounts are torn this will cause excessive movement of the Engine.
2.) Engine timing. If you Engine timing is off slightly, this will cause excessive shake at idle.
3.) Float Level. If your float level is incorrect, this will cause carburetor overflow issues.

Please post pictures of the throttle slide issue.

Rand

Will do,

I'm in college right now, but when I get home, I'll try to get some picures of the throttle slide.

Silver_Pharaoh

you have no return line to the tank - so no place for the excess pressure to bleed off. the fuel pump appears to be over powering the float.

What about the fuel line going to the fuel tank's neck? (black tube in picture 3)

When the odyessy runs, fuel pours back into the tank through that black line.

Is that the return line?

Silver_Pharaoh

Alright, attached are the pictures of the throttle slide. you can see the dent made by the idle screw, it's now brass colour in the dent.

Can I just fill the dent with JB weld or something?

Apologies for the quality, they look a lot better on my phone, but the forums here resize the images to reduce the image size i guess...

As long as you can still adjust the idle properly, I would leave it alone.

Rand

Okay, will do.

Another question while we are wondering how to fix this over fuel issue,

Should I switch the T I have in the fuel line around? As in put the fuel line to the carb at the top and the return line on the horizon? That way (I hope) more fuel should return to the tank, which might help reduce the amount of fuel going to the carb?

Or is the problem in the new gravity fed tank and pump?
Or maybe the way I adjusted the float in the carb?

I didn't think this was a big problem until I took a step back and thought about it... my odyssey runs fine, but when the throttle is wide open, it seems like it could go faster but it doesn't...


Thanks for the help so far everyone!

Silver_Pharaoh

ahhhh - so you do have a 3way valve. I wonder if your on the right track with switching it around??? You should be able to look at the manual to see which port on the valve goes to the fuel tank return. this will confurm if you have it hooked up properly.

You really only have a fuel pump, not both gravity and pump. Gravity feed is using just gravity to feed the fuel - the tank plugged directly to the carb.

I agree with randy on the idle adjustment. If you ever do adjust the idle make sure you blip the throttle as you are adjusting it so the adjusting screw does not get hung up on the groove.

First thing you want to do before you do anything else..........wash that critter! Working on a dirty Ody sucks, the cleaner the better.

According to the picture in the manual, the valve side of the three way fuel valve should be on the tank return side. This is set up so that once the fuel bowl is full, it will cause the valve to open and allow the fuel to return to the top of the tank. By the looks of your picture, your Dad has it set up correctly.

1.) Make sure your fuel filter is working properly and check to make sure in fact that the fuel shut off valve is working properly. Just because it is new, doesn't mean that there isn't something wrong in that area. Pull the carburetor off and then pull the bowl off. Blow air through the carburetor fuel line. While doing this, move the floats up and see if it prevents you from blowing air in through the fuel line. If you can still blow air through the valve when the floats have been pushed up then BINGO, there's your problem.

2.) Engine cradle mounts. The FL250 has a funny tripod cradle system for the Engine to mount to the frame. I have had several of these fail on me. When they do, it will cause the Engine to shake ALOT It is usually one of the front two which fail, however, make sure you check all three. A failed mount can cause the floats to vibrate excessively and can cause the carburetor to overflow.

3.) Double and triple check your float height adjustment. When the floats are set too high, the fuel level will be too high and will cause carburetor overflow.

4.) Check your timing. As mentioned before, improperly set timing can cause Engine shake. Think about this, ever been in a car that didn't runs quite right and felt it shake the entire car?

Rand

Alright thanks guys!

I'll look into the manual and confirm if the 3 way valve is hooked up right...

Also, I'm wondering what is the proper way to adjust the float in the carb... the way I did it was this:

put the carb upside down on the workbench then measured the height of the float from the rim of the carb. I made sure it was 20 mm like the manual says.

Is that the right way or is it out of whack?

Silver_Pharaoh

Ha! Randman, we were posting at the same time! =)

I'll wash it and take a look at the carb and fuel line tonight.

As for the 3 way valve... I don't think it's original. I don't think it's even a valve! just a "T" that fits into the fuel line...

Will that do?

Silver_Pharaoh

Okay, It's not the float valve, I can't blow air into it while the float is closed. =)

Also, apparently I do have a check valve installed... It's not "just a T" like I thought, and it's installed correctly!
Attached is a picture of how I set the float height...

and I plan on taking off the check valve after dinner. Any Ideas on how to check if it still works?
Let me know if I'm doing it wrong.

How nasty and dirty is that air cleaner?

Did you check your Engine mounts?

Have you checked your timing yet?

Rand

Air filter is clean, no noticeable dirt and is still oily from the last time I cleaned it.

Engine mount don't look broken and rubber looks intact.

And I'll read up on how to check the timing. Unless it's so simple that a monkey can check it, I won't attempt it until I can get my dad to help me. He is a licensed diesel mechanic and he runs a small Engine shop in his free time so I'd feel more comfortable if he was there to slap me when I start screwing up! ;)


But just a thought... scince I have a new fuel tank over the Engine itself now (the OEM tank was below it right?) I'm wondering if the new pump we put in is not pushing enough fuel to the tank, therfore more enters the carb?

Also, I cleaned the check valve in the ultra-sonic cleaner we have and then blew into it. Air seems to come out more through the top (for the return line) and not so much for the carb (a bit less than the return line, still enough though) but when I blow from the carb, air gets through both ways? I'm confused, this check valve seems to be kinda like a regular "T" pipe, but then again, I don't know how to properly test the check valve.

Silver_Pharaoh

The weight of the fuel traveling back up the line to the gas isn't enough to cause the issue you are having.

Is the tank vented properly?

Does the fuel piss out of the carburetor overflow tubes when its at an idle?



Rand

Tank vented?

Actually, I never though of this.... The new tank contains the original OEM fuel cap and filler neck, would there be a vent in there?

And yeah kinda, when it idles, fuel drips quite fast out the over flow tube and when I rev it up a bit (to stop the shaking) fuel still drips out the overflow, but not nearly as much.


Silver_Pharaoh

Just another question, I still have the carb on the workbench so I would like to know the proper steps on how to adjust it.

Just to make sure It's set right.

Silver_Pharaoh