Topic: Engine shuts down when hot at cruising speed. Starter fails when hot.

[cowpie]

I’m a newbie.  I have a 1976 Honda CB 550F.  I’ve been combing this forum with my symptoms and have run short of ideas.  It has run well intermittently for 3 years.  It has been worked on several times looking for an issue.  I thought I had problems solved after cleaning and rebuilding the carbs last week but problem is back.  Was hoping my problem would sound familiar to someone on this list.  Thanks in advance for any ideas you may have.

SYMPTOMS
The engine dies while riding after warm and seems to be heat-related.  The engine seems to flatten out/lose boost/pause/stall/choke while accelerating with throttle.  It eventually dies all together and I’m potentially stranded until it cools down or switch to the reserve tank (gas is full in both).  Problem with the clutch?  Cable is tight and gear switching easy.  I’ve had the carbs cleaned and rebuilt.

After initial carb service, gas temporarily dumped from lines but doesn’t happen anymore.  Sometimes engine coughs a little while warming up.  I figured this may be normal after the initial service: purging debris remnants from system.

When the engine dies while riding (I can feel it struggling to produce power in waves), I am always able to get home after switching petcock to the reserve tank.  Sounds like gunk in the fuel line but this has been cleaned. The gas tank vent is also clean and open.  The gas tank has also been cleaned with acid and all rust removed.  Air filter cartridge was replaced with four brand new pods.  Bike performed well for a week, not back to square one.

In addition, the electric ignition easily starts when cold but will fail/click when hot.  I can always easily kick-start it.  Battery was replaced last year.  Cells are full.  Battery on a trickle charger that is charging at 12.6V.  Battery measures at 9.7V when engine is off and 10.7V when on.  I know this is low.  Problem with regulator rectifier/stator?  Breaker points look ok. Could spark plugs be misfiring at high temps?

I suspect there are two issues: fuel/mechanical and electrical.  The main problem is the engine shutting down, and this could be due to a high heat/electrical issue BUT why would switching the petcock to reserve fix the problem and allow me to get home?  The other is the charging system failing to hold juice.  Interrelated?

Clutch?  Spark plugs?  Rectifier/stator?  Clogged fuel/air intake somewhere?  Failed cylinders when hot?  Possible carb valves have slipped back out of place after recent tune?

WORK COMPLETED
Carbs cleaned and rebuilt with new kits
Fuel line cleaned
Gas tank cleaned
New air filter pods
Oil changed
Chain cleaned
New battery
Solenoid previously replaced
Breaker points inspected
Front brake caliper changed

Thoughts? Ideas? Miracles?  Thank you.  Will post picture of bike soon.

[iron_worker]

If switching to reserve solves the problem then you have a blockage instead the main passages in your petcock. Basically can't be anything else.

IW

[cowpie]

Thanks for your reply. I tend to agree with you, cleaned petcock out and worked fine for a week. Acting up again now and fails only when hot. Was thinking engine vibration was causing rust to come loose and mix with fuel after running a while so had the whole fuel/carb system cleaned out. I can't figure out what may be clogging it. Heat seems to be the culprit.

[cowpie]

Also how would starter issue be connected if temperature is the tell sign?

[iron_worker]

Your tank is likely rusting badly from the inside. You may also have a liner that is failing.

Does switching the petcock to reserve cure the problems immediately or does the bike need to cool down? What makes you think it's related to heat?

IW

[iron_worker]

10.7v is dead as stone.

http://www.energymatters.com.au/renewable-energy/batteries/battery-voltage-discharge.php

Below 11.0V is considered 0% charge. Either your battery has crapped out on you again or your charging system has problems.

Which brings me to my next point ... if your voltage is that low it could be that you're riding the bike and the voltage is dropping low enough that the coils won't fire anymore.

IW

[cowpie]

I had the whole gas tank cleaned with acid and resealed with a new liner.  It was in need of cleaning but by no means falling apart.  Heat seems to be a factor because there is no starter or engine trouble until the bike has been running a while and engine is hot.  Switching petcock cures immediately.  After it cools, the main tank will work again.

I do suspect charging system problems and will be replacing the rectifier which are known to be bad in this model.  Perhaps heat causes electrical failure which then affects the coils.  Maybe the petcock solution is just a fluke but is the only way I can ever get the bike back to the garage.

[iron_worker]

If switching to reserve cures the problem immediately then it's a fuel problem. No two ways around it.

I don't think heat has anything to do with it. I think as the bike sits it allows fuel to trickle back into the main passages that are partially plugged. So when you start off on "main" you're using up the fuel that has built up in the bowls and lines...then as it starts drawing down that fuel it starts to starve out again because the blocked passage doesn't allow enough fuel.

Take a flashlight and try to look around in your tank. You may be one of the many with failed liners. Yes even brand new liners fail when improperly done.

IW

[Jerry Rxman Griffin aka MuthaF'er]

Low fuel delivery = lean running condition = over heating = your symptoms possibly. With this in mind perhaps your fuel lines are weak, getting warm and collapsing?

Now with this said, have you mentioned that when this occurs the engine will still turn over? Let's rule out piston expansion. Were the piston rings gapped properly when last installed?

Don't know 550's. Manual petcock or vacuum shutoff/petcock? I'm betting it has the same petcock my 75 CB750F has. Take it apart and check it. When this happens slip off the fuel line at the petcock and make sure you have flow in on and reserve.

Fuel filter? Which type?

On to your battery which is PROBABLY your problem as IW describes. New battery time. I got an AGM battery at Advance Auto ( ~$80) AFTER they load tested (important) my 12.6v battery. It read 12.6v but had about 15cca only. Charge it fully before placing it in service! Fire her up then and check your voltages across the battery terminals as you increase the rpms. It should go up to 14.5v. If not then we worry about why. They do NOT charge at low rpms, they DIScharge. If your 'trickle' charger is not a 'maintainer' then get one, keep it always plugged in and save the 'trickle' charger for your car.

[cowpie]

Thank you.  You've given me some homework which is helpful.  To respond to a few comments to IW & Jerry:

1. I will check the tank but literally just had it thoroughly cleaned.  Your idea that the engine is burning what is in the supply line then trickles back after switching petcock makes sense.  Perhaps a kink in the line somewhere.
2. I will inspect the fuel lines and add a fuel filter.  Any suggestions on best type?
3. Manual petcock.  Will inspect for flow both directions.
4. After engine dies, I can always kick-start it, just have to stay on the throttle because it wants to die.  No problem after switching petcock.  Not super familiar with piston rings but will do some reading.
5. Battery - got a new lead acid last year but went dry pretty quick.  I refill it with distilled water.  It seems to "boil"/gurgle when charging which doesn't seem good.  Do AGM batteries retain fluid better?  Can they lay on their side if I wanted to move under the seat tail one day?
6. The charger I am using is a Battery Tender Junior with quick connect. 
Thanks again.

[iron_worker]

If your battery is boiling out then it is being over charged or something. The only time they every boil is if they are under very heavy load. I would guess something is very wrong with your charging system and you look into that immediately. Putting a new battery in it will just kill it too if you don't solve the problem first.

IW

[cowpie]

Isn't the purpose of the regulator rectifier to maintain continuity between AC/DC and prevent battery from frying? Could be the culprit. Thx.

[HondaMan]

Can you post a picture of your fuel line routing?

[Jerry Rxman Griffin aka MuthaF'er]

More thoughts:

Rectifier takes out the A of the AC which turns it into DC. Only lets one side of the 'alternating' through to the system. Regulator tells the field coil what to do to achieve the proper voltage by supplying more/less voltage to it to cause a change in the output of the stator coils.

If you have the petcock I think you have (you don't see below) then why not install the correct in-tank filter? 
16952-341-671  STRAINER SET  $23.91

 CB550F A MOTORCYCLE, JPN, VIN# CB550F-1109886
CB550F A (76) MOTORCYCLE, JPN, VIN# CB550F-2000003 TO CB550F-2010866
CB550K A (76) MOTORCYCLE, JPN, VIN# CB550K-1230001
CB550K1 A MOTORCYCLE, JPN, VIN# CB550K-1200001

Kick starting with a soon-to-be deceased battery will actually cause a faint spark to be thrown. May start but won't run very good at first until the rpms go up and the charging system starts it's output. More output at higher rpms. The 750 doesn't output until 1800 rpms. It draws on the battery until that point.

You're good with the Battery Tender

When the tank was coated was the petcock left in to plug up the hole?

AGM are maintenance free. I've never laid one on it's side.

Boiling and gurgling on the bike? I can say I've seen that with bigger chargers but not my Battery Tenders. You're going to have to get some kind of battery just to check your charging system.

Piston rings must have a gap set during install to account for thermal expansion. No gap = too tight and the consequences that brings. They are not plug and play.