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I am working on a 1967 Honda C77 "Dream" that I got as a restoration project a couple of months ago. The first objective was to get it running so I could do some riding this summer before a complete tear-down and restore next winter so I changed the oil, overhauled the carburetor, cleaned and set the points, and had it fired up last Wednesday. When I tried to fire it up on the following Friday, it wouldn't start!

Since then I have checked the valves - didn't have the clearance number with me in the shop but each rocker is slightly loose at TDC on the compression stroke.

I replaced the petcock that was causing me trouble with a brand new all-brass valve and a fuel filter. Found some fine debris in the float bowl so I took the carb off, took it apart, and blew out all the passages with compressed air before putting it back together and back on the bike.

I checked the cam timing by aligning the T mark on the rotor and the slash mark on the points cam was at the top and perpendicular to the cylinder bore.

Pulled both spark plugs and checked for spark - good spark at the right time (F mark on the rotor). Plugs look clean and maybe slightly damp from gas. (I replaced the points - worn out lobe - with electronic ignition.)

It still wont fire up! :( It cranks fine, sound like it is just about to fire up, but never gets any further!

I am about at my wits end on this motor! I am about ready to drop it off the bike and start a rebuild instead of waiting for winter :icon_mad:

The only thing I can think of is burned valves (1 or more) but that doesn't explain why it ran on Wednesday and wouldn't start on Friday! I have been around engines my whole life but this one has me puzzled! Maybe I am missing something ubber simple or maybe it is just f'ing with me!!!

Any of you "experienced wrenchers" have any ideas????
 

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American Legion Rider
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Vacuum leak? Just a wild guess on my part Dianne.
 

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Discussion Starter #3
Vacuum leak? Just a wild guess on my part Dianne.
Possible. There is an O-ring between the carb and a spacer and another between the spacer and the cylinder block - I will change them both and re-install with grease to make sure they seal. I will also check the spacer for cracks while it is off.
 

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Try flooding it on purpose. Twist the throttle all the way and crank it. Then check the plugs and see it there wet.

Sounds to me like you missed something in the carb and you're not getting any gas.
 

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Retired twice: Navy and as a govt contractor
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****Hijack***

Jack how is the new shop coming along?

***endofHijack***
 

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You actually SAW the spark at the spark plug right when it hit the F mark? [good spark at the right time]. I don't understand how this happens. Maybe you mean that the test light lights up indicating the points break at the right time.

What you might check is to make sure that the spark plug wire is good all the way to the end including the resistor in the plug cap. They can get dirty and not work right, but will come apart to clean [if they are like my Hondas ]

I use a timing light more to check spark than I do to set timing. It is the quick and easy way to verify spark past the coils into the plug wires. Then move on to the next test procedure.

I do remember one odd thing that happened to me and at least one other guy and that is the points spring grounded against the case when the bike warmed up.Not much clearance in there so setting the insulating washers on the points was critical. One would have thought that the tank vent was plugged, but the timing light found the problem showing a weak spark...
 

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Discussion Starter #12
You actually SAW the spark at the spark plug right when it hit the F mark? [good spark at the right time]. I don't understand how this happens.
I have X-ray vision!

Seriously, remove the plugs from the cylinder, set the big end against the cylinders and crank - presto! - spark right there.

Maybe you mean that the test light lights up indicating the points break at the right time.
That too.

A timing light is normally used to refine timing at RPM.
 

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Sorry, I was not trying to crack wise..... keep us informed on what you find.
 

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Once upon a time, in a shop far far away, there was a little motorcycle that the owner couldn't get running...

It still sits there today I think.

the biggest mistake that I have found that keeps machines from working is the carburetor float problem... NOW LISTEN UP
the floats must close; Not open. If the floats keep the valve open, it floods the engine. The object is that there is a fine line between rich and lean, and a rich engine will melt the valves.
If you are running an aluminum head or block, the valves won't melt, the metal surrounding the valves will. AND
if it ran fine when you tested it, then there must be something keeping it from running fine now.

on the lighter side....
please don't fart when you are checking the timing.. it might blow your ears off.
 

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I had a similar problem on my 74 Honda. I put the plugs against the block to check for spark. Had plenty of spark, just not in the right place. Turned out the plugs were shorted our and the spark was going straight through the threads to the block, never making it to the electrode. Changed the plugs and it fired right up.
 

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I had a similar problem on my 74 Honda. I put the plugs against the block to check for spark. Had plenty of spark, just not in the right place. Turned out the plugs were shorted our and the spark was going straight through the threads to the block, never making it to the electrode. Changed the plugs and it fired right up.
It never dawned on me that could have been the problem. I've changed plugs as a very last ditch effort when the plugs looked just fine and had lawn mowers fire right up that wouldn't before. It never made sense. So maybe that's exactly what was happening. Since then I change plugs right off the bat. They are cheap enough so why leave room for doubt.:)
 

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Discussion Starter #17
Even putting gas directly in the spark plug hole made absolutely no difference so I decided to pull the engine down. It was suggested one or more rings may have stuck the last time it ran (a week ago) and that's exactly what I found - not one or two stuck rings but ALL SIX! No wonder it had no compression LOL!

http://www.diannebest.com/Projects/Honda Dream/C77%20Dream2.html

On the positive side, the bores look great and the valves aren't too bad - looks like most of the damage was from sitting for decades. Gasket set, oil ring set, and piston rings are on order.
 

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Discussion Starter #18
It never dawned on me that could have been the problem. I've changed plugs as a very last ditch effort when the plugs looked just fine and had lawn mowers fire right up that wouldn't before. It never made sense. So maybe that's exactly what was happening. Since then I change plugs right off the bat. They are cheap enough so why leave room for doubt.:)
I have had that experience with plugs as well. I have had plugs that fired good in open air but wouldn't spark at all under pressure. If in doubt, throw 'em out!
 

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Glad you found your issue!

Those bores do look pretty darn good for sitting so long.

Have fun!
 

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Feels good to figure out the problem, and now you have a course of action. Well done
 
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