1964 Honda Dream CA78 Rebuild-storation

[sarals]

Bob, that's a really nice photo!

Oh, is that Dream ever gorgeous. I'm anxious to see what you do with your 750. AND a 400F!

[G-Man]

Bob

I never thought that I would want a white Dream but your workmanship and care has made that a really fetching machine.

Very nicely done. :-)

G

[Bob750]

Okay. So our Dream's been running well in the year (and about 500 miles) since I finished the restoration. I did notice a while back that oil has appeared at the spark plug hole area on both sides. Then today, while my wife and I were out for a little ride around town, I was trying to diagnose a brand new strange idle behavior (just dies, hard to restart, idles then dies again), I find this... (19 sec. video).

I'm really quite afraid that it's the dreaded skull separation issue that I'd read about before but dismissed because, thankfully, our bike didn't have that problem... The other side has some oil there too, but it doesn't bubble and seep like the left side does.

I haven't done anything since we got it back on the lift except check the oil. 1/2 way between marks with the dipstick just resting in the hole, but looked good, since I changed it a hundred miles ago.

Any comments about this? We're very sad.

-Bob

[Bob750]

Okay so I may have to deal with the skull issue later.

Right now we're having a troublesome situation with the engine not idling when it gets hot, as in: not until we've ridden about 45 minutes on a hot day kind of hot.

Please read about the problem in detail over in the Carburetion - Fuel section. There are HD videos with audio so you can see and hear what's happening. I'd really appreciate any input that could suggest the problem and solution. My wife is really bummed and so am I. Cant have the bike quit at every stop. It's troublesome to start and keep running when this happens, and we end up limping it home.

Thanks!

Bob

[G-Man]

Bob

I'm wondering whether the two problems are related. i.e. once the head gets warmed up it begins to let oil into the combustion chamber, fouling the plugs....

Another possibility is the condenser which is perched atop the cylinder cover. Have you had a look at the points when it's misbehaving?

G

[Bob750]

Hey Graham!

Well, at first, before I even saw the plugs, (remember way back in a previous post how beautifully tan they were?) I was convinced it had to be just an idle mixture issue causing the faltering when hot, since, when the engine gets hot after riding a while--like, at least 30 to 90 minutes depending on the weather, etc--it only then has trouble idling. It goes at speed just fine. Then you come to a stop and suddenly it falters and dies and is very hard to restart. if you catch it with the throttle in time, you can keep it running, but it will always want to quit below 1/4 throttle after hitting this "critical temperature." However, above idle you can "ride it all day." Last year we went on a 60 mile round trip down and up the coast, and it never gave any kind of trouble. So it seems this idle problem is a more recent thing. But attributable to what?

But if it does quit, you gotta push it to the side and kick it and kick it before it starts again. However, if left for an hour. It'll turn over with a tiny flick of the starter and putt along at a perfect idle as long as you want it to... until... you get it hot enough. Temperature is the only thing that reproduces this symptom.

The fouled plugs were discovered as I started troubleshooting. Black. That picture doesn't convey my expression when they both came out that way.

So is that unburned fuel? If so it would indicate a very rich condition, and should be accompanied by black sooty exhaust, right? I have none of that.

Is that black stuff on the plugs just coked engine oil? If so, it would indicate oil being pumped by our very low pressure oil pump into the combustion chamber via the path provided by a hot, less-than-OEM head gasket. But again, one would think you'd then see a lot of white smoke puffing out the pipes. None. Well, maybe not none. If you stick your face right up to the the hole, you can sometimes see very faint wisps of something light, but it never produces a cloud. It's more like water vapor in appearance and ephemeral quality. And we all know that good combustion yields just water vapor and CO2.

So technically, it could be a little of both richness and oil burning. But again, not enough smoke to suggest either. I'm going to order an OEM head gasket, because it's seeping anyway, and if replacing it cures something else, then good.

This really is perplexing.

As for the points. Interesting you should ask. I did pull the covers off the point and dynamo to do a dynamic timing test with my strobe. The idle timing was right on and the advance worked perfectly and locked in right between the marks. But I did notice sparks "squirting" out sometimes from the contact points. I shut it down, cleaned the points with the card and brake-cleaner trick and lubed the cam felt. After that the sparks stopped squirting out, and the firing seemed "more regular," if that makes sense. I haven't taken it out since then. I'll give it a run soon to see if it does the same thing again.

Oh, and how would the condenser be involved in this?

[G-Man]

Bob

The condenser snuffs out voltage spikes as the points operate and stops arcing. The traditional condenser failure is when the engine gets hot.

Bad spark means poor running which may look like un burnt fuel,,,,,,

G