Topic: 1978 CB750A - Kill switch conspiracy

[jwdenos]

Hi this is my second real post,.. Last time I had purchased a 1978 CB750 Hondamatic that sat for a while.  After placing every piece of the top end on a bookshelf, in the shed,I have it back together.

I don't seem to be getting a spark though :-( ... the kill switch is not working properly. The switch allows the bike to turn over in the 'OFF' position and instantly blows a fuse(15A) when switched to the 'RUN' position.
Unplugged this and that... with this and that left plugged in.. still nothing.
took apart the kill switch and cleaned/fixed it up. It was a mess, I think it was working fine though, only filthy.

lights/gauges work
engine turns over
no spark
battery drainage
kill switch funk

Any "leads" [har har ] will be greatly appreciated.

Now I am going to look in the gauge cluster for a short... I took everything apart on this bike already to clean it and did not expect to run into such a perplexing problem.
One question also;I took good care not let anything get inside the case. If the bottom end the engine was sitting around in the shed for a bit and then tossed around to clean as well as mount back in the frame sideways,... question is would this have an adverse effect on wiring inside the engine or messed up the generator somehow?

Thank You again.

John











UPDATe: ok I took apart the kill switch again and the wires on the connector pad were laying down and exposed.

thanks err body hope this is it..

UPDATe#2: The fuse is no longer blowing out when I switch it to RUN. The bike will still turn over in OFF position. The bike will not turn over in the RUN position. Checked the stator and only one coil seems to be good. Even worse I now realize that I have been jump starting it with a 70A 12v charge from a heavy duty charger. I will use the 2A 12V setting from now ON! I am going to remove the stator and look at it.

ANother thing is when the ignition is on I can hear the battery sizzling pretty well,.. no matter what the kill switch is set to....

any help on this issue will be greatly appreciated!

Thank YOu,

John

[jwdenos]

http://youtu.be/NP0mQeLWCCo

[Don R]

If your battery is sizzling turn it off before something bad happens. The kill switch turns off the coils, the engine will still spin over on the starter. I assume that is what you were referring to.
 Look in the manuals at the top of this page or go to oldmanHonda.com and download and print the color wiring diagram. Follow the wires in the headlight bucket until you are sure everything is correct.
 There is a good thread on testing the charging system or buy Hondamans book. I would do that, auctually I did that.  Use search and read until you are sure of the test procedure.

[jwdenos]

Thanks, I have a stigma about electrical... it gives me a headache. I have the wiring diagram and will study it, as well as search the forum.

I was hoping someone could perform a little internet magic or something...

SO yea,.. it's been a while since I started the bike and that makes sense that it would turn over in OFF position haha.
The reason I stopped blowing fuses is because the battery drained... so I am back at square one.

I guess I'll take the harness out again, ran out of tape...

http://thumbs4.ebaystatic.com/d/l225/m/mD3cmAu1F8YgQrkKErMmiqw.jpg

[jwdenos]

Ok suckafishes,.. I found that the bracket for the coils had been assembled all inside out n stuff, by yours truly ...

So no more blowing fuses. Now just wont start,.. it' sprays fuel out of the back of the carbs. I suppose that's an ignition timing problem. Now I am to adjust the valve clearance,.. adjust the points,... then adjust the valves again and then the points agian? Or should the settings remain after cranking the engine?

That's the question now, because it seems that the valve clearance keeps getting messed up... as well as the points gap. (maybe I am needing more practice at setting the points)

oh well ... lets hope for progress.

-John D.

[jwdenos]

here is a great youtube on the chain tensioner that is not in my factory service manual

https://www.youtube.com/watch?v=8841eO5tvro

[jwdenos]

https://sites.google.com/site/hondamaticmotorcycleclub/Resources/cb750a

[jwdenos]

I'll let people know that the head is off again and I have  torque wrench in hand.

[jwdenos]

Have the bike started... then it blew the oil cooler hose... AWESOME ... haven't been so happy to blow a hose before, it's 15 years old I should have known better.


My problem was that I did not install the camshaft at TDC.

Also, I ordered new valves from Partnsmore and the ones they sent have a longer notch cut for the collars.. I am wondering if that matters so much since the cam was set wrong. the surface of the valve stem that connects with the rocker is raised higher above the spring than the stock valves due to the collars being set lower on the stem.


is it ok to have mismatching valves or will this interfere with the timing geometry?.. I will contemplate this while I sleep.

to be safe I have the old valves in.

[jwdenos]

http://youtu.be/y_7p6t07GhI

[Bailgang]

here is a great youtube on the chain tensioner that is not in my factory service manual

https://www.youtube.com/watch?v=8841eO5tvro

The only problem I have with that vid is that it stresses having the #1 cyl at TDC on the compression stroke. I understand having 1 and 4 at TDC but what difference does it make if the #1 cyl is at TDC on the comp stroke rather than TDC on the exh stroke? If #1 is at TDC on the comp stoke then #4 is at TDC on exh ..... or the other way around meaning that the cam chain preload you're trying to avoid is still there at TDC whether #1 is at TDC on it's comp or exh stroke which is why turning the crank 15 deg past TDC is needed. Someone please explain.

[madmtnmotors]

is it ok to have mismatching valves?

No. But you already knew that, didn't you?