Author Topic: Dad's 1978 Honda CB550k (Read 15537 times)

BenelliSEI · « **Reply #350 on:** September 30, 2023, 08:53:00 AM »

This photo might help. See the two hatch marks furthest to the RIGHT of F1.4? You want to see those centred up on the fixed mark at 3000 rpm. Adjust the location of the points plate until they are perfect. Then do the same for 2.3, using the other set of points. Full advance is more important than the idle setting. Assuming your points gap is close, the idle mark should be very close when you nail the full advance. Good Luck.

joegeis · « **Reply #351 on:** September 30, 2023, 09:20:50 AM »

Thanks guys! I feel like I actually understand what I'm doing now!

This morning I reset the points gap (very minimal adjustment, seems like it was okay).

However, when I tried to set static timing, I can't get the test light to come on AT ALL. I think I'll just move on to dynamic timing, but I would like to understand why this is. Is it a side effect of adding the Hondaman ignition, or should that not matter? I have not attempted static timing since before I replaced the coils and added the Hondaman ignition, so I'm not sure.

Is it possible that at idle to have the timing correct, but at 2,500+ rpm for it to be off? How do you adjust one without affecting the other?

newday777 · « **Reply #352 on:** September 30, 2023, 09:32:52 AM »

Quote from: denward17 on September 30, 2023, 08:46:24 AM

I don't know 550 bikes that well....

Could it be from a bent shaft on the end? see this thread....

http://forums.sohc4.net/index.php/topic,193574.0.html

The 500/550_FOUR has a bolt (#14) as apposed to the shaft on the 750, but it is an actual 6x55mm bolt and I might be wrong but that could conceibly be bent in the same way by not removing the spark plugs before turning the 23mm nut/advancer bolt and the compression putting too much resistance when turning the motor over.

joegeis · « **Reply #353 on:** September 30, 2023, 09:44:20 AM »

Okay, so I used the strobe and I have good and bad news.

Good news - I can hold a steady 1,000-1,200 idle, and the readings look very good at the F line. Not bouncing all over the place.
Bad news - I can't hold a steady 2,500 idle. I can walk it up to 2,000 with the idle screw, but then it doesn't want to go higher. If I rev the engine a little, it flies to 5,000. I can walk it back down to ~3,500 with the idle screw, but any lower and it quickly falls back to ~1,200. I assume this is related to the advancer springs being shortened.

Eventually I let it sit at 3,500 rpm, just so I could get a timing reading with the strobe. The marks lined up for both sides directly between the two full advanced marks (far to the right of the F marks). I took it for a test ride and the throttle is now kind of snatchy. It idles more evenly and doesn't feel like it will stall when warm. However, it has lost power under 3,000 rpm, and then it suddenly jolts forward and quickly accelerates north of 3,000 rpm.

So if I understand correctly, my timing is good, but my advancer is bad? Is there a good aftermarket advancer sold anywhere?

newday777 · « **Reply #354 on:** September 30, 2023, 09:54:12 AM »

Just use the idle screw for standard idle speed. Set it to 1000-1200. Leave it there. It isn't designed for 2,500.
Do all other rpm changes with the throttle grip or get a clamp on cruise control.

joegeis · « **Reply #355 on:** September 30, 2023, 10:00:39 AM »

So I was able to test it at 3,500 rpm. I'm pretty sure I have the timing set correctly. However, while it idles nicer, it rides much more poorly. What do I need to adjust or replace to smooth out the rev ranges?

BenelliSEI · « **Reply #356 on:** September 30, 2023, 05:51:39 PM »

The advancer I posted a picture of is sold by Vintagecb750.com. It’s specifically sold for 1969-78 SOHC cb750’s. Not sure if it will fit your cb550. Maybe someone here can tell you?

newday777 · « **Reply #357 on:** September 30, 2023, 06:06:23 PM »

Quote from: BenelliSEI on September 30, 2023, 05:51:39 PM

The advancer I posted a picture of is sold by Vintagecb750.com. It’s specifically sold for 1969-78 SOHC cb750’s. Not sure if it will fit your cb550. Maybe someone here can tell you?

The 750 is different from the 500/550

joegeis · « **Reply #358 on:** September 30, 2023, 07:30:14 PM »

found this one:

https://www.davidsilverspares.com/CB550K-1978-USA/part_370574/

I've not used David Silver Spares before, but I believe I've seen good things around the forum?

grcamna2 · « **Reply #359 on:** September 30, 2023, 07:33:10 PM »

Quote from: joegeis on September 30, 2023, 07:30:14 PM

found this one:

https://www.davidsilverspares.com/CB550K-1978-USA/part_370574/

I've not used David Silver Spares before, but I believe I've seen good things around the forum?

That'll work; NOS,cool

joegeis · « **Reply #360 on:** September 30, 2023, 07:49:27 PM »

This one is actually listed as an "aftermarket" part. Hopefully it's better than the one on 4into1.com that I could have gotten faster and cheaper!

BenelliSEI · « **Reply #361 on:** September 30, 2023, 08:09:38 PM »

It will make a difference.

joegeis · « **Reply #362 on:** October 01, 2023, 11:34:29 AM »

Had some time today, so went for a ride, even though the advancer is still causing issues. As I felt on the test ride yesterday, I had low power under 3,000 rpm, followed by a jerk in torque after that, and I was still having the engine get "stuck" at 4,000 rpm at every light. I also had the tachometer stop working on me , so I'll need to dig into that as well. I did order the David Silver Spares advancer, so hopefully that solves all my engine speed issues!

BenelliSEI · « **Reply #363 on:** October 01, 2023, 02:11:53 PM »

I’d suggest that “stuck at 4,000 rpm is not ignition related. It’s carburation. A carb (or carbs) hanging open, not returning to the idle setting? Air leak at manifolds?

Have you done a carb sync on your idling engine with 4 X vacuum gauges? It sounds to me like you have one or more carbs running way ahead of the rest…….

grcamna2 · « **Reply #364 on:** October 01, 2023, 02:14:11 PM »

Quote from: BenelliSEI on October 01, 2023, 02:11:53 PM

I’d suggest that “stuck at 4,000 rpm is not ignition related. It’s carburation. A carb (or carbs) hanging open, not returning to the idle setting? Air leak at manifolds?

Have you done a carb sync on your idling engine with 4 X vacuum gauges? It sounds to me like you have one or more carbs running way ahead of the rest…….

Might also be the return throttle cable being adjusted too tight

joegeis · « **Reply #365 on:** October 01, 2023, 05:47:29 PM »

I've done a few carb syncs, and its always been tough to do because I struggled to keep a steady idle, and it would want to "walk" up the rev range. I should redo it now that I have a steady idle. A few pages back, I was having issues with what I thought was a sync issue on carb 2, and ended up making BIG changes to carb 4. It's totally possible that is still an issue. I've taken the carbs off and messed with the throttle cables so much that its definitely possible that I have them misadjusted as well. So I understand, would a too tight return cable make the throttle tube return poorly? My throttle does "snap" closed easily on its own, the RPMs staying high is not consistent with the throttle tube being open.

I have replaced all the intake rubber (from airbox to carb and carb to engine). All the seals are tight. Is there some way for me to test if I have an air leak?

Feels like I'm going in circles!

BenelliSEI · « **Reply #366 on:** October 01, 2023, 06:51:08 PM »

You’re getting closer. Now that you have the idle sorted, do the carb sync again. I bet you find one carb that’s way too open and causing your wild idle return.

Use the adjuster on the pull cable and make sure it is quite slack when the carbs are at rest. It’s only and “emergency cable” to pull them shut in the event something jams.

joegeis · « **Reply #367 on:** October 07, 2023, 11:18:57 AM »

its only 50 degrees here today, and it was much more difficult to start the bike. It had been sitting for a week while I was out of town. I couldn't use any choke, but just had to crank it for quite a while and slowly feather the throttle. Once started, here is what I did:

* Checked mixture screws - all are 1.5 turns out.
* Confirmed throttle return cable was not over tight.
* Swapped my foam air filter our for a stock paper filter.
* Sprayed intake manifolds with starting fluid while running. No impact on idle speed (I read that this can help identify vacuum leaks, if the RPMs jump)
* Rode bike around block until it was nice and warm
* Hooked up to sync gauges and confirmed all carbs were still in sync. I made zero adjustments.

I did order new intake manifold gaskets, even though I see no evidence of a leak. I also still hear a put of sputter and pop from cylinder 2 and "feel" it if you put your hand at the exhaust. I took a video at the exhaust so hopefully you can hear it. I'm not sure if this is a related or separate issue.

Video with sputtering

Once warm, the bike did start the thing with the idle walking up and "sticking" at 3-4k rpms again.

calj737 · « **Reply #368 on:** October 07, 2023, 01:44:24 PM »

I have to wonder if you’re aren’t operating the choke in reverse? Your symptoms and start up procedure sure sound like it…

grcamna2 · « **Reply #369 on:** October 07, 2023, 01:44:53 PM »

Have you received your new advancer mechanism from DSS ?

joegeis · « **Reply #370 on:** October 07, 2023, 01:51:03 PM »

the advancer hasn't shown up yet unfortunately.

Regarding the choke in reverse... I wouldn't put anything past me, but I'm not sure how this would be possible. I'll take a discerning look at it to confirm...

grcamna2 · « **Reply #371 on:** October 07, 2023, 02:36:21 PM »

Quote from: joegeis on October 07, 2023, 01:51:03 PM

the advancer hasn't shown up yet unfortunately.

Regarding the choke in reverse... I wouldn't put anything past me, but I'm not sure how this would be possible. I'll take a discerning look at it to confirm...

I hope your choke lever has the word 'open' with an arrow; 'open' is Choke Off.

BenelliSEI · « **Reply #372 on:** October 07, 2023, 05:15:11 PM »

The ‘78 550K has a choke cable you pull from up near the key switch? When fully pulled out it is also designed to very slightly open the throttle. Maybe that is out of adjustment and hanging your idle?

joegeis · « **Reply #373 on:** October 08, 2023, 07:33:58 AM »

Quote from: BenelliSEI on October 07, 2023, 05:15:11 PM

The ‘78 550K has a choke cable you pull from up near the key switch? When fully pulled out it is also designed to very slightly open the throttle. Maybe that is out of adjustment and hanging your idle?

Yes, I have the choke up by the handlebars, and its been functioning correctly. Pulled all the way out tips the high idle and bumps the throttle up to 3-4k RPMs. Push it halfway in and it releases the throttle. It is stiff to pull out and there is no way it is getting pulled out while riding.

Another change I made that may be related - I added a small in line fuel filter after I had the leaky carb issue. Could that be starving my fuel supply and causing things to run lean? I'll get that petcock strainer installed finally and remove the inline filter.

Also, I just remembered that my wife has an uncle that has restored a few vintage Hondas over the years who lives local (yes, I'm an idiot for getting this far and never thinking to go see him before). I'll go see him and have him take a look at it soon too.

grcamna2 · « **Reply #374 on:** November 04, 2023, 07:51:41 PM »

Joe,how do all 4) of your spark plugs look;have any of them gotten a bit fouled/dark while doing all this start/stop tuning ? You may need a new set,if any of them have gotten fouled a little.. I just wanted to mention this, 'just in case'.

I also wanted to ask you: how's the cam chain;have you adjusted it? it may be a little loose still?

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Author Topic: Dad's 1978 Honda CB550k (Read 15537 times)