Topic: 1976 CB550F starting issues

[Alex95]

Hey guys,

I recently bought a '76 CB550 and I'm in the process of getting it running smoothly again. When I bought it, it did run although idle was very rough and it bogged down without added throttle. I rebuilt the carbs and installed new air filter, spark plugs etc but now it doesn't run anymore. It only runs briefly when using start pilot. Here's some things I changed/tried:

• Change spark plugs
• Air filter
• Electronic ignition
• Battery
• Cleaning the petcock

I checked the plugs and there's a spark. Do you guys have any idea on what my next step could be?
Thanks in advance!!

[Alex95]

Thank you for your reply.

The timing for the electronic ignition is set correctly. It came with a light to check if it is set correct. I called with the supplier and he also confirmed this.

Rebuilding the carbs included gaskets, jets, emulsion tubes, needles, pretty much everything. I installed the same size main and idle jets as standard (it had this before too).

Air filter is replaced with the exact same model as stock. I didn't go for any non-original replacements, apart from the electronic ignition.

I tried starting it with choke open and closed and with and without air filter.. none have worked so far.

[TwoTired]

Have you verified fuel is getting to the carbs?

Do the spark plug tips get wet after you try and start the bike?

You sure you didn't put the e ignition in 180 degrees out of phase?  Does your ignition replace the spark advancer?

I hope you saved the original brass from your carbs.  Aftermarket parts have been known to be problematic.

Cheers,

[Deltarider]

Rebuilding the carbs included gaskets, jets, emulsion tubes, needles, pretty much everything. I installed the same size main and idle jets as standard (it had this before too).
Air filter is replaced with the exact same model as stock. I didn't go for any non-original replacements, apart from the electronic ignition.
I tried starting it with choke open and closed and with and without air filter.. none have worked so far.

You did many things at the same time which makes it a bit difficult to diagnose. I read you've been at the needles and even replaced them (btw why?). Are you aware carbs need to be resynced after that? Did you do this and how? If sync is very much out of wack, this could cause what you describe. But the ignition needs to be double checked first. You have spark, but did you check 1+4 and 2+3 have them at the right cycle? Sometimes people accidentely reverse the wires (blue and yellow resp.). Did you 'toevallig' have the advancer apart? If so, check the little mark in the rim faces the little hole (in the pic white encircled).

[Rudi91]

Alex is my younger brother, I'm helping him on this project.
We changed the needles because they were a little bit different from the stock ones and since we replaced the jets etc. we figured it would be best to replace these as well. Thinking they are made for the rest of the kit. We used the kit of cruzinimage btw.
The carbs havent been synced yet because we don't have the proper tool for this. Alex will have a specialist do this because that will be cheaper than buying such tool.
The advancer has been apart because the thing in the middle (no idea what it's called in English) had to be replaced by one specially made for the electronic ignition.
We are using this kit;


From what I recall the light has to light up only at TDC but it's on half a cycle, it goes off when cylinders 2 and 3 reach TDC. Does that seem right to you guys? We can move the plate around without the light going off

[Alex95]

Have you verified fuel is getting to the carbs?

Do the spark plug tips get wet after you try and start the bike?

You sure you didn't put the e ignition in 180 degrees out of phase?  Does your ignition replace the spark advancer?

I hope you saved the original brass from your carbs.  Aftermarket parts have been known to be problematic.

Cheers,

We just verified the electronic ignition again and that is correctly installed.

Now I'm thinking it is a problem with fuel. I opened the float bowl drain screw and only a few drops of fuel came out. That is strange because no fuel is leaking out either. We then tried feeding it fuel with a syringe directly into the carburettors through the fuel lines, but it still didn't run. There is a lot of pressure in the system and when removing the syringe, fuel bursted out. This leads me to believe that something  somewhere is clogged up as fuel still didn't come out of the float bowl drains.

[flatlander]

are you having these problems when starting up a cold engine? if so, then there may be nothing wrong at all.
on a cold start, choke closed, you need to keep the throttle cracked open a bit to keep the revs up otherwise. with closed throttle the engine will die again. the carbs and choke on the 550 F1 (which i suppose you have of ot os from 76) are an old system that needs actual manual operation.

[Alex95]

are you having these problems when starting up a cold engine? if so, then there may be nothing wrong at all.
on a cold start, choke closed, you need to keep the throttle cracked open a bit to keep the revs up otherwise. with closed throttle the engine will die again. the carbs and choke on the 550 F1 (which i suppose you have of ot os from 76) are an old system that needs actual manual operation.

It is on a cold start, yes. The motorcycle hasn't run in a few weeks (it did run when I bought it, but with a very rough idle). It will not idle with or without choke and I've also tried it with the throttle applied in various ways.

Using start pilot it does run (very) briefly, which leads me to believe that it burned the start pilot to run for a bit and when that is gone, it would be starved of fuel and bog down.

[flatlander]

i guess with "pilot" you mean the fuel in the carb bowls?
if that does not refill with petcock open then indeed, you need to go over the fuel delivery system first.
tank clean, petckock clean, in-tank fuel filter present and not clogged, fuel lines not clogged, correct size (5.5mm) and routed correctly.... that should get fuel flowing to the carbs. then try again.

and sorry for the typos - stupid little phone!

[TwoTired]

Have you verified fuel is getting to the carbs?

Do the spark plug tips get wet after you try and start the bike?

You sure you didn't put the e ignition in 180 degrees out of phase?  Does your ignition replace the spark advancer?

I hope you saved the original brass from your carbs.  Aftermarket parts have been known to be problematic.

Cheers,

We just verified the electronic ignition again and that is correctly installed.

Now I'm thinking it is a problem with fuel. I opened the float bowl drain screw and only a few drops of fuel came out. That is strange because no fuel is leaking out either. We then tried feeding it fuel with a syringe directly into the carburettors through the fuel lines, but it still didn't run. There is a lot of pressure in the system and when removing the syringe, fuel bursted out. This leads me to believe that something  somewhere is clogged up as fuel still didn't come out of the float bowl drains.

Stating the obvious, the motor can't run without fuel.

If your gas filled syringe presurizes the fuel line without the carb dumping the fuel out the float bowl drains, that is a fuel delivery issue.  Either lines clogged, or the float valves are stuck closed, blocking fuel entry into the carbs.

Cheers,

[Alex95]

i guess with "pilot" you mean the fuel in the carb bowls?

With start pilot I mean the spray cans with fluid to help it start.

I just checked the floats and their height was way out of spec. Adjusted that to 22mm and tried giving it a go, but unfortunately the bike still has the same issue.

The float bowls are still empty. Fuel is flowing well through the tank, but I don't know where it gets blocked yet. I'll be going through the system tomorrow.

Edit: checked the fuel hoses too and they are open and flowing.

[Deltarider]

I just checked the floats and their height was way out of spec. Adjusted that to 22mm

Sure? Because not many ever touch the floats, let alone that they change the heights. Just for certainty's sake, can you inform us how you measured and adjusted? You may want to consult p.60 of the Shop Manual Honda CB500 - CB550 for the correct procedure. https://www.classiccycles.org/media//DIR_1653304/DIR_1653404/DIR_1653507/ecc6759db0a214d5ffff881effffe41e.pdf or perform the socalled cleartube test. BTW, what manual do you use?
Any extra inline fuel filters that can hinder fuel flow?
Are all the carb air vent tubes open? And the brass overflow pipes at the bottom of the carb bowls? Sometimes after a long period of inactivity the float needles stick closed. If this continues to be a problem (intermittently), add a socalled fuel system cleaner like Forté or Tunap to the fuel. They work.

[robvangulik]

What is your hometown, when it's not too far away i'll be happy to lend a hand to get this bike running!

[RAFster122s]

Starting fluid is pretty volatile and can be dangerous...ether.
Yes, a fuel delivery issue is present as is pointed out.

There is a bench sync procedure you need to follow after disassembling the carbs. It is detailed in the factory shop manual.

The original carb brass usually is good after being cleaned and unless it is mismatched it is really the best solution for these carbs. Keyster and other aftermarket carb brass has proven to be problem ridden, whereas the stock Keihin jets are usually trouble free.  Naturally if a Previous Owner (PO) has drilled that brass all bets can be off.

David

[Alex95]

I just checked the floats and their height was way out of spec. Adjusted that to 22mm

Sure? Because not many ever touch the floats, let alone that they change the heights. Just for certainty's sake, can you inform us how you measured and adjusted? You may want to consult p.60 of the Shop Manual Honda CB500 - CB550 for the correct procedure. https://www.classiccycles.org/media//DIR_1653304/DIR_1653404/DIR_1653507/ecc6759db0a214d5ffff881effffe41e.pdf or perform the socalled cleartube test. BTW, what manual do you use?
Any extra inline fuel filters that can hinder fuel flow?
Are all the carb air vent tubes open? And the brass overflow pipes at the bottom of the carb bowls? Sometimes after a long period of inactivity the float needles stick closed. If this continues to be a problem (intermittently), add a socalled fuel system cleaner like Forté or Tunap to the fuel. They work.

Double checked the valve float height now and it seems to be spot on now.
Just reinstalled the carbs and the float bowls seem to be filling up beautifully now.

I will try to start it later today. Let's hope that fixed it.



Edit: When going through some of the wiring I noticed four wires with female connectors that were disconnected. I can't find any wires that need to be connected to these. I checked the wiring diagram and the coloured ones don't seem to have an essential function, but I'm not so sure about the black one being disconnected.

[Alex95]

That Black one looks to be power to the idiot cluster. The Brown/White is also switched power to the gauges. The Blue/ and Orange/ with White stripe are Turn indicators for the idiot cluster.

Looks like someone has been tinkering with that harness well before you 

This were my thoughts too, but the thing is that all the lights in the cluster work perfectly

[Deltarider]

No, no, no, these wires are ment for the silly looking running lights in the blinkers that toy market US had. Ignore them. Find the appropiate wiring diagram for your model and 'area code'. You'll see they're there... blind, even the black one.

[Alex95]

Ok, so I tried starting it up today and I've got a new problem.

Instead of describing the problem I thought a video would be much easier:

I also heard this bang when I only put the key in and put it on contact the first time (without even touching the starter).
I'm wondering if it is just some unburnt stuff that's in the system somewhere as there's some kind of white powder ( ) inside the air intake. It looks to me like deo spray that's in a solid state.

Do you guys think it's safe to continue trying to start it?

[Alex95]

Sounds like you have the ignition cam or plug wires backwards.

To be clear, 1 coil serves cylinders 1&4, the other 2&3. Swap the wires from the ignition to the coils (Blue and Yellow) on the coils and try again.

That seems to have done the trick, thanks a lot!!

It still has an issue with idling, once I stop applying throttle it will bog down. This was the case when I first bought it also, any idea what the cause of that may be?

[Alex95]

Fuel level, incorrect settings of carbs, not properly tuned, valves out of adjustment, etc...

Start at the beginning. Get your fuel levels set properly with a Clear Tube test (clear tubing inserted into bowl drain screw. Fuel shuold be 3-4mm below bowl seam.

Ignition set properly (I know you have electronic, so let’s assume you have that right)
Valves adjusted properly.
Warm up engine with choke, remove choke and set idle via Set Screw to 1100 RPMs. Vacuum synch the carbs.

Ride the dog sheet out of it and enjoy! 

I'm going to follow this list to get it running smoothly again!

Thanks again for the help everyone. You guys are the best 

[Deltarider]

The appropiate wiring diagram for your model is in the last pages of http://www.honda4fun.com/pdf_libretti/550/550F_76/librettoCB550F_76_4.pdf I'd consult the GERMANY TYPE. I'm confident that you will find your 'blind' connectors presented in it. BTW, if you don't have 'starting issues' now, you will definitely have them if you go on trying to start as shown in your vid. Poor starting motor... If a Japanese bike of that era does not start within say 7 seconds, stop trying because it is telling you something is wrong that needs to be adressed.

[Alex95]

The appropiate wiring diagram for your model is in the last pages of http://www.honda4fun.com/pdf_libretti/550/550F_76/librettoCB550F_76_4.pdf I'd consult the GERMANY TYPE. I'm confident that you will find your 'blind' connectors presented in it. BTW, if you don't have 'starting issues' now, you will definitely have them if you go on trying to start as shown in your vid. Poor starting motor... If a Japanese bike of that era does not start within say 7 seconds, stop trying because it is telling you something is wrong that needs to be adressed.

The starting issues are over now luckily, it starts right up with the electric start and also with the kicker.

The idle problem was a simple fix too. Now it only has a bit of a flat spot in higher RPMs that I have to sort out, but I noticed most of the rubber for the inlet has some cracks in it.