Topic: Sometimes, they find you. 1971 CB500

[Scott S]

Have you tested the oil pressure and neutral switches?

 Other than making sure the wires are on them, no. Bike isn't running yet. I can pull the sprocket cover and take a look, but the fact that the lights are flashing tells me the circuit is good..... no?

[BenelliSEI]

The switches send a ground feed (-) to the lamps. The power to the lamps ((+) comes through the key switch and should be ON, whenever you have the key ON. The fact that you can “flicker” them with the key switch makes me think key switch internals are the culprit

[newday777]

The switches sent a ground feed (-) to the lamps. The power to the lamps ((+) comes through the key switch and should be ON, whenever you have the key ON. The fact that you can “flicker” them with the key switch makes me think key switch internals are the culprit

Exactly

[grcamna2]

The contact points on the plastic base of the switch and their setting/alignment is important.
I take OEM ignition switches apart and crimp/reset the base when assembling and it's a win over aftermarket as they're usually just dirty.

[Scott S]

 Checked the fuse, the frame ground and inside the headlight bucket. Also tried another ignition switch. Still having the same issue with the Oil/Neutral lights. Guess I'll pull the sprocket cover soon and look around in there.

 I did finally check the points and static timing. Going by some other things I had found on this bike (like valves WILDY out of adjustment), I expected the timing to be FUBAR. What a nice surprise to find that they need only very minor adjustments.
 Installed the new plugs and now I wait for warmer weather. Maybe I'll get the gumption to fire it up soon!

[Scott S]

 Pulled the sprocket cover to take a look at the oil and neutral switch wiring....all good.

 Took the opportunity to disassemble the worm gear in the clutch lifter and clean out 52 year old grease. I had greased the mechanism, but noticed that it was still really stiff when I tried to adjust the clutch.
 Cleaned and lubed everything, squirted a few drops of oil down the clutch cable and readjusted. Best it's felt since I had the bike. I'll see how close I got once the bike is running and up to temp.

[grcamna2]

Pulled the sprocket cover to take a look at the oil and neutral switch wiring....all good.

 Took the opportunity to disassemble the worm gear in the clutch lifter and clean out 52 year old grease. I had greased the mechanism, but noticed that it was still really stiff when I tried to adjust the clutch.
 Cleaned and lubed everything, squirted a few drops of oil down the clutch cable and readjusted. Best it's felt since I had the bike. I'll see how close I got once the bike is running and up to temp.

You close to 'turn key' ? ! 

[Scott S]

 Well, I finally got up the gumption to fire up the '71 CB500 today. Before installing the carbs, I set the carb linkage to the 49mm discussed earlier in this thread. I checked the main jet O-rings and they were tight, so I didn't change them.
 The bike fired right up (after sitting for 25 years) and....you guessed it: HANGING IDLE!!!

 This is why I stopped working on bikes for so long.

 I'm running points and set them statically. I put the timing light on it and it's close enough that it's not an issue. I will be converting to electronic soon, so I didn't mess with it.

 I didn't sync the carbs since I'm assuming they will be coming back off.

 I do have some questions about the 49mm setting.
 I took pics BEFORE the carbs were rebuilt and you can still see the factory marks. It was mentioned earlier, on a different bike, that too many threads were showing on the sync screws. But look at how many are on here from the factory.

 When set to 49mm, I have to screw the main idle screw WAY in. It feels like it's too much, but that is what is required to get the 49mm. After achieving that, I bench synced the carbs.

 After bench syncing them, the sync screws look WAY different than the factory settings.

 I have a set of HondaMan's O-rings. I will be pulling the @#$&^* carbs and installing those. I will be going back closer to the factory settings on the sync screws and see what happens.
 I'm open to other suggestions.
 On a positive not, it runs well, with no smoke, leaks or funny noises!

 * First pics are before; factory settings. Middle pic shows the rack as delivered from OldSkoolCarbs (looking like factory settings Later pics are with the 49mm setting *

[grcamna2]

I like the progress 

[Scott S]

 Not sure it's progress when I have to take #$%* apart again.

 However, I will take "no leaks, smoke or death noises" as a small victory.

[grcamna2]

Not sure it's progress when I have to take #$%* apart again.

 However, I will take "no leaks, smoke or death noises" as a small victory.

Scott,have you went for a ride on it today ?

[RAFster122s]

It is getting closer Scott, so don’t fling it off the middle of a bridge yet…

It will be nice when done and running well again…look ahead. Kiss the girl friend and walk away from it when it frustrates you…
When it does good things kiss the girlfriend… when it does bad things kiss the girlfriend…
Just get your mind off the bike for a while and give the girlfriend attention. She should appreciate the attention…

David

[Scott S]

Not sure it's progress when I have to take #$%* apart again.

 However, I will take "no leaks, smoke or death noises" as a small victory.

Scott,have you went for a ride on it today ?

 Just up and down the street in front of the house, with the gas in the bowls. I was able to go  through all the gears. Runs good, will probably need a minor tweaking on the clutch adjustment.

 But first, the carbs gotta come off again.

[Scott S]

 I give up.
 Pulled the carbs today and set the slides back to factory settings.  Installed HondaMan's O-rings and bench synced them.
 Got it back together and it STILL has a hanging idle.
 I sprayed carb cleaner everywhere and I have no vacuumleaks. The throttle cable isn't sticking.
 I guess I'll pull the advance mechanism and check/clean it. Maybe install the Tytronics at that time. See what happens.

[grcamna2]

I give up.
 Pulled the carbs today and set the slides back to factory settings.  Installed HondaMan's O-rings and bench synced them.
 Got it back together and it STILL has a hanging idle.
 I sprayed carb cleaner everywhere and I have no vacuumleaks. The throttle cable isn't sticking.
 I guess I'll pull the advance mechanism and check/clean it. Maybe install the Tytronics at that time. See what happens.

My guess is the advancer assm. Scott.

[RAFster122s]

HondaMan mentioned the advancer springs that are worn will sometimes develop this if the springs fatigue too much 8n a thread a while back. Maybe cut 1/2 loop or full loop off one side and see what that does to your full advance rpm. Would be a good idea to see what rpm it is currently going full advance on.
If it is the springs, then if the Tyronics uses the advancer it won't fix the problem.
Would be worth a try to tighten up the springs to bring full advance to a higher rpm with today's gas.

Waiting to hear what you find.

David

[Scott S]

Pulled the carbs again yesterday. The last couple of times I've pulled them, I've been using a method based on the 550 Assembly Manual sticky posted here. I remove the battery/tray, hang the electrical panel off the left side, and completely remove the air box. It sound like a lot of work, but it makes it SO much easier to get the carbs in and out. The last few times I've done it this way, I've had the carbs out, adjustments made and bike back together and running in about 3 hours.

 Since the last time I "cured" this issue was by using aftermarket main jets with snug fitting O-rings, I ordered a set of 100's. When I got the carbs open, I realized that the Hondaman O-rings fit the best of anything I have. They are all snug and tight and I don't think they are leaking by. I also checked the float heights and they're all good.
 These carbs are super clean. The emulsion tubes will drop right out, all brass is genuine Keihin, etc.

 Pulled the advancer and checked/cleaned and lubed it. I put a drop of 3 in 1 oil on each post where the weights attach. Cleaned the cam lobe inside and out and put the thinnest smear of brake part lubricator grease on it. The springs felt great. I've had worn out springs before and these snap back nicely.

 Reassembled the bike and ...yep... still hanging. I figured I'd try a vacuum sync and see what happens. That did seem to help a little, but not cure it completely. Then the throttle cable started getting hung up.

 The cable hasn't been an issue, and I lubed it at both ends with a couple of drops of 3 in 1 oil. When the cable came out of the adjuster at the handle bar end, the outer sheath frayed a little. That is causing an issue now.
 I found an aftermarket cable in my stash and will swap them out and see what happens.

[Scott S]

 A friend in Ohio posted pics of his new 350F and I noticed the mirrors. I traded him a set of bar ends for these genuine Honda mirrors. These are correct for the '71 and in nice shape. They fit much better than the aftermarket mirrors. The stalks are staggered lengths to make them even when mounted.

 If the throttle cable cures the hanging idle, I'll drop some coin on e genuine Honda cable. The aftermarket cables work fine, but the adjusters aren't chrome. I'd like to keep this bike as OG as possible.

[RAFster122s]

Man, that's a frustrating bike to be hanging up the idle after all that work if it doesn't turn out to be cable related. The Honda throttle cables are special... aftermarket just doesn't compare and price isn't that much more given the lack of issues the OEM has....
Hope the cable fixes it.
Does the carbs have really smooth movement or does the return spring make it impossible to really detect any small nuance?
Makes you wonder if a burr is somewhere in the mechanism making an intermittent drag that causes the hanging idle.
Have you ran it without the filter box and been able to see the carb slides to see if they are hanging up or all closing down identically?
No leaks showing up on intake manifold or carb insulators?

[Scott S]

 No leaks. Forgot to mention that. The last time it was running (before yesterday) I checked for vacuum leaks and found nothing. While the carbs were off yesterday, I made sure all of the intake manifold nuts were tight. I rebuilt the head, so I installed new manifold O-rings when they went back on.

 I always go back to the intake clamps (both sides) once the bike is warm and snug them up. Whatever is causing this, I don't think it's a vacuum leak. I even sprayed around the carb bodies and found nothing.

[RAFster122s]

While you have the cable off check to see if it hangs when you operate the throttle manually... Might reveal if it is something mechanical with the cable routing ...

[Scott S]

 Today was a good day .... I think.  Replaced the cable and tweaked the mixture screws and I'm 96% sure I cured the hanging throttle. Mixture screws ended up at 1/2 turn out, which I know isn't right and is a sign of something else being off, but that's what the bike likes. I may try swapping the UNI filter for a stock paper filter.

 I felt confident enough to put the bike back together. I'll go get some gas this week and take her down the road. I know the clutch needs final adjustment, but I'll do that when the engine is good and warm.

 Here she is, fellas!

[Scott S]

 You don't know what a big victory this is for me!

[newday777]

That sounds great 

[RAFster122s]

Uni filters are tough to not over oil and that leads to richer mixtures... Too much variability possible in oiling them.
Congratulations on getting it to idle nicely! Must make you really happy!