Problem of the year!

[mitchell.lee.miller]

So I posted my ride--it was a bad pic, and I'll work on that, but I'm at the end of my wits with my issue here....

I fixed the carb leak a couple of weeks ago by replacing the o-rings, put new gas in the tank, and yesterday took off the carbs and cleaned them.  

I'm still not feeling heat from cylinder 2.  I checked the plug, and did the 'lawn mower test.'  There is definitely spark.  The carburetor is clean and in good shape (I think).  Why isn't this cylinder going for me?  The engine fires up immediately and is ready to go, but where is my second cylinder?  Sticky valve?--This scares me the most--leaking gasket?  Anyone have any ideas?

Will it every run on all four?

[shinyribs]

Air+fuel+spark=run. You just gotta figure out which one your missing.

And you know you have spark,so now you're down to fuel and air.

over simplified of course,but thats how i sort mine out

[mitchell.lee.miller]

Okay, do I take that carburetor apart completely?  Look under the head cover?  Where do I start?

 

[Lucky 1]

So you found out that you have spark on #2 cylinder?

[Lucky 1]

You said you thought the carb is clean. Is it?

If the idle jet is clogged no fuel will go to that cylinder when trying to start it.
Lets back up.
What year is this bike?
Don't just start ripping things apart.

[Re-run]

If you are not getting #2, then most likely your idle circuit is plugged. People "clean" these carbs but most never know to pull the idle jets out and the fuel screws and clean in there. The jet particularly need a physical cleaning. A strand of copper wire run though each and every hole along with carb spray.
Also, pop off the bottom of the accel pump and pull out the pump and clean all the holes and such there. Make sure both ears of the pump are open. If you have an aftermarket one, sometimes one comes closed.

Now once you have everything back together, the backside(engine side) of the slides should all be set to 1/8 inch or so to give a rough "bench" sync. Mount then back on and hook up fuel. Leave off the airbox and turn on the fuel. Give the throttle a twist and you should see a stream of gas shoot into the 4 carbs from the brass nozzles at the front of the carbs. This verifies the accel pump is active. The manual states the gap for the pump. It is something like .008 inches. If you do not have this gap, it will not pump right.

At this point, you should be ready to fire. IF the issue still occurs, swap the wires from 2 and 3 and try again. If the issue stays, swap the plugs. If it still stays, then something is still boned in the carb. You DID set the floats to 14-15 mm right?

[mitchell.lee.miller]

Lucky1--it's a '77, there is spark on #2.  I haven't tore anything apart.  

Lately, I've been absorbing a lot about these carburetors.  Things I didn't know about but now do: Main Jet, Idle Jet, Accelerator Pump, Float settings, and 'Timing/vacuum.'

Tomorrow after work--I'll take off the air box to check the accelerator pump, then after that clears it's check (hopeful), I'll pull the carbs out and actually clean them (last weekend I just sprayed everything with carb cleaner) so this means I'll (thanks Re-run) remove the Idle Jet screw and clean that out first and then clean out the Main Jet--did this pretty well last time (without knowing what I was really doing), but then I'll check those float distances.  They should all be good--I was mindful of that last time (my dad told me to make sure all of them looked very similar?).

Any other advice?      ....Thanks guys.

[TOOLS1]

Pull the pilot jets, and clean them.
TOOLS

[mitchell.lee.miller]

Check this out:

http://www.salocal.com/sohc/tech/carb/dspg_mgs/adjstr1.htm

I like it.

[mitchell.lee.miller]

So last weekend...I got the carbs all cleaned out took out every jet, idle jets first, and found everything was pretty clean but not clean enough.  So I did a thorough carburetor clean, almost like I was a dental hygienist.  All perfect.  

Then, I reset all the slides to height recommended by the website I found (I posted it previously).  That was easy enough, and I set the float distance (again according to the website).  Now keep in mind I have round top carburetors, I think they are '76.  The website told me to set the floats to a distance of 26mm!  So I did, I trusted the website, also referenced the Clymer...which said 26mm.  That is from the bottom of the carb to the bottom of the float, with the float lever just touching the nipple on the needle.  Rerun, you said 14-15mm, where you talking about round tops like mine (just asking because I do not have an accelerator pump needles)?  I'm also asking because after putting it all together, the bowls stayed bone dry.  Roxanne wouldn't even start.  So I hand poured gas in the bowls to see if that would help and she started...sickly, but cylinder #2 was hot--and smelled funny--probably because it hadn't run in a while.

Who was right about the distance of the floats?  --I think you might just have to adjust all this stuff to what works?

So yesterday...I adjust all the floats up big time to give plenty of fuel to each carburetor, I did this just by taking the air-box off and dropping the bowl and one by one bending the small tabs a bit.  I made sure they were all done equally.  Before I put the air-box on I started it...it fired right up.  Except #2.  So I put my hand over to carb #2, (a very manual choke, right?) and it instantly responded-rev!  I covered up the holes and had to go to work...haven't touched it since...

WHAT DO I DO!?  

I think I just have to keep playing around with it..I'm gonna put the air-box back on and see if that is enough of a choke to keep #2 going.  I read on another thread that the air-box is like a big choke (only allows 39% of the air in).

I also think I might pop out the Idle Jet and clean it out again on #2, and also try adjusting it all over the place.

Does anyone have any input or advice?


These are my carbs--pic from the day I fixed the leak.

 

[shinyribs]

The easiest way to set the floats is just set them level.

Where are your idle mixture screws adjusted at? Turn them all the way in until they just lightly seat,or stop.Then back them out 1 1/2 turns.Your bike MAY need more turns out,but that should be enough for it to run correctly

The true way to adjust your idle mixture screws is to start at 1 1/2 turns out and then slowly open them more.If the motor speeds up then it needed the extra idle mixture.Once the motor stops increasing rpms by doing this,that is where they should stay.

Good luck!

[Piute]

Re-run wrote

If you are not getting #2, then most likely your idle circuit is plugged. People "clean" these carbs but most never know to pull the idle jets out and the fuel screws and clean in there. The jet particularly need a physical cleaning. A strand of copper wire run though each and every hole along with carb spray.
Also, pop off the bottom of the accel pump and pull out the pump and clean all the holes and such there. Make sure both ears of the pump are open. If you have an aftermarket one, sometimes one comes closed.

Now once you have everything back together, the backside(engine side) of the slides should all be set to 1/8 inch or so to give a rough "bench" sync. Mount then back on and hook up fuel. Leave off the airbox and turn on the fuel. Give the throttle a twist and you should see a stream of gas shoot into the 4 carbs from the brass nozzles at the front of the carbs. This verifies the accel pump is active. The manual states the gap for the pump. It is something like .008 inches. If you do not have this gap, it will not pump right.

At this point, you should be ready to fire. IF the issue still occurs, swap the wires from 2 and 3 and try again. If the issue stays, swap the plugs. If it still stays, then something is still boned in the carb. You DID set the floats to 14-15 mm right?

   My KEY-TOPS are 14-15 so be sure of yours 1st off ,getting mine on this wkend myself I hope.

[Lucky 1]

Answer of the year.

Those are NOT 1977 carbs.

The blue hoses are fuel lines going into the carbs.
That clear loop of fuel line is float bowl vent lines.
The green hoses are float bowl drain and overflow lines.
That clear loop of hose has to vent to atmosphere.
The clear loop of fuel line instead should be two separate
vent lines so that the throttle return spring can go in between the two vent lines.
The throttle return spring is attached incorrectly.

BTW...I am the one that told you that the air box is a giant choke and the opening is only 30 something percent of the total intake areas of the carbs. That is for a 1977-78 and you
do not have 1977-78 carbs.

[Piute]

Lucky 1 wrote

Answer of the year.

Those are NOT 1977 carbs.

The blue hoses are fuel lines going into the carbs.
That clear loop of fuel line is float bowl vent lines.
The green hoses are float bowl drain and overflow lines.
That clear loop of hose has to vent to atmosphere.
The clear loop of fuel line instead should be two separate
vent lines so that the throttle return spring can go in between the two vent lines.
The throttle return spring is attached incorrectly.

BTW...I am the one that told you that the air box is a giant choke and the opening is only 30 something percent of the total intake areas of the carbs. That is for a 1977-78 and you
do not have 1977-78 carbs.

                                       THAT THEY are not 1977 stk. carbs,here's #4 carb

[Lucky 1]

Not sure what you are trying to say...

[mitchell.lee.miller]

...I think he is showing a '77 carb as an example.  Also thanks for all your input, I am learning a lot here.  I have made the adjustment to clear tube.  Also all of those lines started blue and have faded, and since been replaced.  

Who uses blue tubes?  Why?  Why not the black fuel lines that have a smaller inner diameter and larger outer diameter?  What was factory?

Also if anyone can tell me what year these carbs that would be great?  Possibly a link to reference page of '70s Honda motorcycles with their respective carburetor makes and models-jet size?-and how to identify carburetors-especially kei hin?  

[mitchell.lee.miller]

nevermind these are 76 carbs...

[cdaiscool]

All this talk about fuel+spark+air...

How's the compression? Can't run without 100 psi of compression.

Also, crank it/run it then pull the plug. Does it smell like fuel? If so,  you're getting fuel. Nobody's said to do that either.

I see the title says its solved, but then I see more questions regarding it. So, if its not solved, then I'd go compression. Otherwise, congrats!

[mitchell.lee.miller]

That is what I'm working on now---solved was referring to the carbs.  I was just looking into compression tests.  The other day my dad and I made a fitting out of an old spark plug and a compressed air fitting.  He is going to teach me how to...

The next thing is to set the engine at the right timing, and loosen the automatic cam chain tightener.  

Then the next thing is to pull the valve cover, and then...about this I am still teaching myself.  I hope to find some things may just need adjusting, and there isn't any sticky valves or mangled cam!  If anybody has any advice I'm all ears.

Keep in mind, I'm not a mechanic-that's my dad.  I am trying to learn all of this myself/stay out of the house heh.

[cdaiscool]

You have an SOHC, I have a DOHC.

Download the service manual and read that over. That'll tell you what you need to know. Also, you may need a special tool to lift the cam up to get the shim out. It's all of $5 or so.

Mine was relatively easy; yours is going to be much more difficult. Do some investigating before you remove the valve cover so you know precisely what you're dealing with, and can head off any frustrations early.