Topic: CB is off on sick time- AGAIN, BUT FIXED IN A JIFFY

[Kevin D]

Last time out (Tuesday) after work ride, got stuck in rush hour traffic 15 minutes to clear one signal. Went to accelerate and got a pronounced misfire. It was time for dinner so we stopped, ate, let the bikes cool down and decided to return home 30 miles. Bike was still missing badly but cleared up just a bit.

Now its Saturday, time to check it out. I recalled a gas overflow after my recent brake repair, so I drained the float bowls and noted #1 bowl overfilled/spilling. 2, 3, 4 equal level a bit below the top of the bowl. I removed #1 float and can hear the fuel sloshing around inside. I dropped it in water for a test and one side is way down, so now I am hunting a replacement. This is the second brass float that has failed, the first was replaced with the black plastic type. I will probably get the same plastic float again.

I have new plugs on the way, haven't pulled the old ones yet, or checked anything else for that matter.
This is a new experience for me, that my CB is running poorly.
Gotta fix it ASAP for some late season riding. I sure don't want to make a winter layup under these circumstances.

[Stev-o]

That is odd. Are those genuine Honda floats or aftermarket?

[Kevin D]

It is the original float and the second that has failed. On the first go around I tried to resolder the joint but was unsuccessful.

I'm thinking an oil change might be in order. I tried a sniff test on the oil tank but I don't have a calibrated nose.

[70CB750]

You can solder the floater.  I done it for Dorothy, long time ago.

[Kevin D]

You have skills Procop, I'm ham handed.
I gotta get the fuel out first and then I might give it a try, if I can find the leak.
Too bad Virginia and Michigan aren't a little closer.

New Denso plugs just showed up from Rock Auto, time to put them in and check coils and caps as well.

[ekpent]

 I have replaced all the brass in K1's before with plastic and been fine and no more worries. Probably got a couple brass ones around here still in Kazoo if you get in a jam and need one but no guarantee how long it would last though if still good.

[Kevin D]

Well thanks Eric, but I got a new one ordered, probably plastic. I just gotta wait for shipment now. Seems I am gonna replace them one at a time

I swapped the spark plugs out and yes, #1 is sooty. Also found a bad plug cap on #4
Plugs are 3 years, 6500 miles
Caps are 11 years, 25000 miles

I have had several plug caps go bad over the years. Maybe next time around I will try resistor plugs and 0 ohm caps.

[Kevin D]

I found another bad plug cap, on #1. If I pressed the the test probes in just a certain way and with lots of pressure, I could make it read 5000 ohms. Anything else would get 30-40k ohms or more, so that one was also replaced.
 I went for an 80 mile test ride out to Dexter and back. The first 60 miles were great and then the misfire returned  I limped home, managing 70 mph on the M14/I275.
 Time for another work session. I opened the points, checked the condensers, both OK. While setting dwell/timing, I noted a fair amount of sparking on the 2-3 side so I went to the used parts bin and salvaged/tested/installed a different condenser. Noted lots less sparking. I might figure out a hi temp test for the iffy condenser.
 Waiting now for decent weather for a test ride. Sunny and 47 today, too cold for for an 80 miler, supposed to be 65 tomorrow, but out of town family visit squeezing CB time. This will get fixed, I'm just going at it slow as a turtle.

[Johnie]

Agree with Eric. I replaced all my brass floats a while ago with the plastic. Was not worth the hassle. As soon as I would get one fixed another would die. Ride on man...

[BomberMann650]

It is so nice to have the know how to diagnose and repair these bikes!!
Hope you can enjoy your remaining riding season

[Kevin D]

It is so nice to have the know how to diagnose and repair these bikes!!

I didn't mention, there was a recent thread and a CB with similar symptoms. PeWe posted a YouTube of a bike with sparking points. Just fortunate for me that the CB doesn't need much, and I can tap into the forum knowledge when necessary.

[ekpent]

 A bad condenser will make it run like crap. Let us know how the next test run goes.

[Kevin D]

run like crap

Yep, it runs like crap after an hour or so. But I got a short, cold, and passable test run yesterday.

I have had a couple other poor running episodes loooong ago:
- an emulsion tube unscrewed itself and fell to the bottom of the float bowl a couple weeks after I "cleaned" the jets and bowls. It ran, but not very well. I won a bottle of wine at a local poker run riding it like that. Took me about a week to find my error.
- I have always run Shell gas in the CB: Super Shell before, now  Vpower. For some reason I switched to Mobil. After a few tanks of Mobil the CB started running bad, missing under hard acceleration. I could not figure it out, usually just ride it hard to decarbonize the plugs. But I was out riding one night, went to reserve, and a Shell station was the only one open for miles, so I got the Super Shell, and after just one tank, my CB was purring again! Never been back to Mobil.

EDIT: when the weather broke, I got a good long test ride and the CB is healthy😀

[Kevin D]

Decent weather has returned so I set out for a nice ride today. 50 Miles from home, the ugly sputtering/missing/running like shxxt returned. But I hadn't forgotten the previous episode caused by a bad condenser. Although I was carrying spares, I limped it home, went directly to the points plate and noted a fat blue spark on the 1/4 side. I swapped the suspect 1/4 condenser with one from my spares and all is well.

Im getting rid of any Daiichi condensers. This one lasted two seasons. The TEC condensers were harvested from my old points plates, any I'm carrying them as spares.
 I don't get it. A condenser is a simple thing, some newer ones are garbage.

[RAFster122s]

Quality of construction of the dielectric layers of the condensers made by Daiichi is awful! The material chosen for the dielectric layers is as cheap as they can get and as a result they short and fail quickly.
I can bet if you dissect one you will find evidence of it arcing through the layers.

[Kevin D]

I can bet if you dissect one you will find evidence of it arcing through the layers.

I have watched the oil filter dissections, and they are informative and useful. But I don't have enough moolah to be dissecting $23 condensers. I might go to the trash and retrieve and dissect the failed  Daiichi. But it will probably be destroyed in the disassembly and I don't know wth I'm looking at anyway other than a piece of foil and film rolled up.

There are 2 grades of condensers offered $10+/- each(daiichi?) and $23 +/- (genuine)
The darned thing is I've had two consecutive failures, the first on a "genuine" points plate, the second with the $10 Daiichi condensers.

Here is a timeline from my logbook:
7/2013   75000mi replaced points plate/points/condensers 30200-300-154 $100 (genuine)
10/2016 81100 2/3 condenser failed (sparking points) replaced from old parts(tek)
4/2017   81500 replaced both condensers with new $10 daiichi
10/2019 86900 1/4 condenser failed (sparking point), replaced from old parts(tek), ordered "genuine"

[seanbarney41]

Kevin, perhaps do you often leave the bike with the ignition on but the engine not running?...Say, moving the bike into the garage so you have the headlight on in the dark?  This is a bad habit that I see some unwittingly have, as it can overheat coils and condensers needlessly so that they do not last as long.  Just a thought...

[Kevin D]

 Sean, I’m generally a kill switch first user. I think that knocks the voltage from ignition parts.
Did you ride down and back to Barber? Sounds nice!

I pulled the rubber seal from the bad daiichi condenser It was just a bit oily inside but smelled like electrical failure. I couldn’t get the guts out, need to grind the rolled lip off.

[RAFster122s]

At least they do not fail like when you put reverse voltage on a polarized electrolytic capacitor, they explode with a loud Bang blowing their guts out the end of the can.  Wasn’t recommending you dissect a good condenser, merely the failed one. Wear gloves if you do dissect one, they are messy.

[PeWe]

Condensers did not live long on my CB750 back in the 80's.
I think I changed at every 15000 km or sooner. I saw the arcing points thru the transparent ignition cover.

Today Hondaman ignition in no really need of them. I noticed minor misfires after 8000 rpm. Ok with codensors.
I have small capacitors to test 0.22 uF, 630V.

[Kevin D]

Wasn’t recommending you dissect a good condenser, merely the failed one.

Understood, but to do a full blown comparo, like the oil filter comparo, the whole variety of manufacturers should be covered. Probably need more sophisticated test equipment than what I have, and some material ID skills that I don't have for the insulating paper/film.

Hondaman ignition

Might be on my wish list for a Christmas gift.

The TEC condensers measured .273uF, even the bad Daiichi measured .21uF

I think I can make out a TEC logo on the DSS part photo:

[seanbarney41]

Sean, I’m generally a kill switch first user. I think that knocks the voltage from ignition parts.
Did you ride down and back to Barber? Sounds nice!

I pulled the rubber seal from the bad daiichi condenser It was just a bit oily inside but smelled like electrical failure. I couldn’t get the guts out, need to grind the rolled lip off.

yep, kill switch should cut voltage to electrical system

nah, would be cool to ride down there some day but would require more days off work.  A friend offered a ride in his van for me and trailer space for my bike, so I took it!

[Kevin D]

Sean, I’m generally a kill switch first user. I think that knocks the voltage from ignition parts.
Did you ride down and back to Barber? Sounds nice!

I pulled the rubber seal from the bad daiichi condenser It was just a bit oily inside but smelled like electrical failure. I couldn’t get the guts out, need to grind the rolled lip off.

yep, kill switch should cut voltage to electrical system

nah, would be cool to ride down there some day but would require more days off work.  A friend offered a ride in his van for me and trailer space for my bike, so I took it!

Being a GHOF makes bending over for the keys a PIA. I'm beginning to understand why so many relocate the ign sw.
Sean your Barber deal was terrific, you truly have a pal there!

[RAFster122s]

Kevin, GHOF?

[Kevin D]

Gray Haired Old Fart

I'm not really, just 66 salt n pepper trying to enjoy retirement
And I want my CB to run tiptop all the time!