Topic: 76 550four idling problems

[JAG]

To check it without the engine running, try to rotate the entire points plate by hand.  Does it snap back when released? 

I don't have a strobe.

When I move to the plate to the right The plate doesn't snap back.
When I move it to the left in DOES snap back.

As per the instructions, it says to remove blue wire attach test light to it. I have the other end of the test light firmly planted and grounded to the bike. I rotate the crank and line up the 'F' mark to the 1-4, and if the light comes on when you hit that spot, the timing is correct. Same instructions with Yellow wire and 2-3 'F' mark.

However, With the blue wire attached to test light, the light will stay Regardless of where the crank is sitting AND Regardless of where I move the Base Plate..

What the heck am I doing wrong. 

[JAG]

Also this may be a stroke of idiocy, but I've never noticed the two tick marks that are to the right of the 1-4 Mark.

I always thought the T mark was the one farthest to the left, and the F mark was the one right next to it..

Wrong assumption??

The springs on the plate are in good condition too.. Nice and well umm Springy!

[OldSchool_IsCool]

hmmm I don't think you should REMOVE the blue wire from the points.  Maybe the green (condenser wire)?  You should see a constant 12+ on a disconnected blue wire (with good battery, key on, kill switch on).  With the blue wire connected to the points, you should see the test lamp go out when the points close (as you rotate the crank).  What more, the test lamp should transition at the F mark.

The two marks to the right are the advance marks.  With a strobe, you would see those marks align with the case pointer at 3500 RPM and above. 

The best way to test for proper "springyness" to with a strobe.  The springs stretched by counter weights that swing out with centrifugal force when the advance is spinning. 

[JAG]

It literally says disconnect blue/yellow wire. At any rate with them connected I got the timing set beautifully. Started her up and she purred at 1050rpms beautifully.
Tried to start synciing the carbs after a good warm up and damnit if it didn't scream up to 3K rpms and then fell out and died. I didn't even touch anything yet.. This is getting frustrating.

While it was warming up I gave a healthy dose of WD40 all around the boots and nothing ever changed... What could it be that is causing this irregularity?

[TwoTired]

Are all the head pipes at about the same heat level?

If there is crud in the float bowls, you may be getting intermittent idle jet plugging.

Do you have enough gas in the tank?  Is there enough to be a good bit over the stand pipe?

[JAG]

Are all the head pipes at about the same heat level?

If there is crud in the float bowls, you may be getting intermittent idle jet plugging.

Do you have enough gas in the tank?  Is there enough to be a good bit over the stand pipe?

pipes are the same in regards to flash touch method.

No crud.

Gas is looking good. I am using clear hoses to be able to see it draining in the carbs.

With the sync tool attached there is absolutely no adjustment to it for some reason. No matter how many times I move the screw clock wise or counter clock wise it doesn't seem to go into the Normal Range. attached is two pictures, one of the sync gauges themselves and one of the close up of one of them. Where the needles start ( at 0 ) The range where they stay is right below it in the RED.

I went through all the valves again to only see that they are all still very good. So they only other option is an air leak. I bought some more clamps to go on the boots. I'll try to get the boots tighter on the manifold and carbs themselves and while they are off I'll lgo through all the cabrs again...

[TwoTired]

Don't pay any attention to what the gauge says is "normal".

Just make sure all the needles have the same reading across the bank.

The Pilot air bleed screw is NOT the sync adjustment.
The sync adjustment is part of the slide actuation linkage.  Pick one carb's vacuum and match the other three to it.  Don't tweak all the adjusters.

Don't you have a shop manual for the bike?

[JAG]

well in that case all the carbs are in sync because they are all reading the same.

Of course I have a manual. That manual told me to disconnect wires from the points when they didn't need to be and it also says it needs to read a certain KG/CM2 level as well. I never went by that I've always just made sure all needles were the same across the board.

[TwoTired]

Are you using the Honda shop manual?

[JAG]

Yes sir and it states it should be at 3.0 cm HG. This manual is far more specific than my supplemental CB750 honda shop manual.

[TwoTired]

Yes sir and it states it should be at 3.0 cm HG.

er...   Better read it again.
It states they need to be adjusted to within 3.0 cm Hg of each other with uniformity in the 16-24cm Hg range among all four carbs.

In the gauge pic posted above, was the engine running while showing those readings?

[JAG]

The engine was not running in that pic. But where they all sit at 0 when it is NOT running, when the engine is running they all sit equally one "tick mark" below that.

I put on the new clamps.

As the engine runs, it warms up and the idle slowly increases. I'll back off the throttle screw and it will sit nicely at 1050-1100 rpms.

After about ten minutes it will rise up to 3K rpms and die. I check all the bowls again to find nice clean fuel, still sitting in there.

I started it back up. It ran for a couple more minutes, rise back up to 3K rpms and quickly dies again. Checking again the bowls there is still clean gasoline in it and no sight of debris. There is not so much as a speck of anything in any of the jets. The pipes are all scolding hot, ( I have the burn marks on my hand ) Timing is set, points are set, tappets are set. The only thing I haven't check is the internals of the engine, so what is left? I have got to be missing something...

[OldSchool_IsCool]

Fuel flow.  You may have just enough fuel flow to keep 'er running for 10 minutes, but she eventually starves.

Did you check the condition of the in-tank filter?  Are you running an in-line filter? 

My rule of thumb is that the fuel system needs to deliver 8 ounces of fuel to the carbs in 15 seconds or less. 

[JAG]

That bowls are still completely full when it dies. When I disconnect the fuel lines which are clear the fuel is all the way to the top. Its got to have plenty of fuel.

No in line filters

[OldSchool_IsCool]

How many seconds pass between the engine dieing and your checks on the bowl level?

[JAG]

However long it takes to unscrew the screw on the bottom of the bowl.

[JAG]

I think the bike just needs to be ridden. These things run better the more they are ran. In just gonna give up on the nonsense and send it back to him. All these hundreds of views and no more input so maybe its nothing.

I'm done fighting with it. I've done all I know to do.

[OldSchool_IsCool]

True, sometimes a good thrashing will solve a lot of ills.  Could be she's just pissed off from sitting in a garage for so long. 

[JAG]

Hahahahaha. True. I know my 750 didn't run well even after tuning until I put a couple hundred miles on it.

[TwoTired]

As the engine runs, it warms up and the idle slowly increases. I'll back off the throttle screw and it will sit nicely at 1050-1100 rpms.

That seems normal.  Engine heat atomizes fuel better so the engine get more efficient.  You are supposed to set the idle speed when the engine is at full operating temperature.  During start up, you must then hold the throttle open some to keep it running.  Some people keep twiddling the idle knob during warm up.
On my 550's, I drive it during warm up, so my hand is naturally on the throttle keeping it going during the drive.  When the engine gets to op temp, it will idle as it is supposed to.

After about ten minutes it will rise up to 3K rpms and die. I check all the bowls again to find nice clean fuel, still sitting in there.

That kind of sounds like it is going lean.  What are the idle screws set at?  And what is your filter and exhaust situation?
Have you done a plug read after it dies?
May also be that a 10 minute stationary idle is making the engine overheat.  Do you blow air over the air cooled motor?

[JAG]

All the idle screws are set to about 1.5 turns out.

I did in fact have a strong fan blowing on the motor at all times.

Actually I haven't done a plug check after it ran. I always pull one when the cylinder isn't firing. Ill check that an report my findings.

The exhaust is factory but the mufflers have been cut off. And the bike didn't come with air box boots and they are being ordered. So carbs are wide open right now.