Topic: How much spark is enough?

[afastman]

So I have finally began addressing the 77 750F I bought a couple months ago.  I pulled the plugs, clean and tan all 4 and reattached the wires (one at a time).  With a brand new battery that lives on a trickle charger, I turned it over a couple times to check spark.  There was definitely a spark.  It was small and orange.  So I thought "OK, guess it is time to dismantle the carbs and get on with it."  I have been trying to systematically find other things to fix for fear of the carb cleaning.  So (knowing I will have to probably do the carbs anyway...the bike sat fro 1.5 years)  what should that spark look like?  I am tempted for about 2 bones each to just buy new plugs anyhow, but i thought i would put it out to the masses first.

[mattcb350f]

You should have a blue arc across the spark plugs. Orange suggests a weak spark to me, but other's might know better what that means.

You should gap the points and set the timing too, or at least check them.

...and as for the carbs, you might as well bite the bullet and tear into them  The jets are soo small that they often get cloged up when parked for a while. Also, the accelerator pump needs to work perfectly for these bikes to run well. after a year and a half, I would think it might be gummed up too.

 Matt.

[cafe750]

Well, the spark should be blue.  The resistors that are in the plug caps degrade over time, and by now, are probably close to dead. It wouldn't hurt to change out your plug caps, and change out the plugs. Also, if your battery isn't completely up to snuff, it'll contribute to an orangey spark.

There's nothing inside those carbs to be afraid of. If you find yourself a large baking sheet pan, with a raised lip around the edge, it'll give you a nice surface to disassemble the carbs on. Just be careful to lay out the pieces in the order that they came out, and if you need to, take pictures.

Hope this helps!

[afastman]

I do not have a manual in front of me right now, but the caps are different from the wires, correct?  Also if the wires have tape on them (which I assume means at the least a hole in the insulation) is there a way to test them or just replace as well?

[cafe750]

The caps unscrew from the end of the wires. The wires came with a heavy rubber cover over the wire, and from the factory, are "permanently" attached to the coils. We like pictures...if you could take a couple of pics of the wires, it'd help alot. 

[WFO]

I have had a spark plug show spark and then go on to not start the bike after replacing it ( she started right up) if you don't know how old the plugs are i would juts replace them and eliminate it as a potential problem.

[TwoTired]

Things to check:

What is the voltage seen at the coil terminals?
Temporarily disconnect the points condenser.  Does the spark get bluer?  If so, replace the condensers.
Do the point contacts look clean, shiny and not pitted?  If not, get new points.
Replace the spark plugs.  Don't use resistor type plugs with the stock resistor plug caps.
Why is there tape on the ignition wires?  Is there damage under the tape?  These wires deliver the spark, if they are leaky, you can expect less spark energy at the spark plug.
Are your ignition leads "wire core" as a stock bike would have?  Or, have they been "mended" with resistance wire?  Is the tape covering a splice?

Cheers,

[afastman]

AAAAAHHHH!

Ok, the good news is that checking that exhaustive list does not scare me.  However...
volt meter...red to the terminal end, black to?  what SHOULD I expect to get? 

I am so new to bikes, I would not know what a factory vs replacement wire looks like.  I will try to get some photos up.  From what I understand, the bike was run as some sort of bobber before the guy i bought it from got it.  He restored the seat to stock.  It still has some funky "z" bars on it and some weird pieces here and there, but I think most of the mechanics are stock.  It does not seem like anyone mechanically savvy ever monkeyed with the essentials.  It was a daily driver before sitting, It will be again. 

I will repost findings.  I will also get the carbs gone through and see where it leaves me.

[TwoTired]

You want to know how much of the full battery voltage is actually present at the Blk/Wht connection to the coils (red meter lead). The Black meter lead would be on the Battery NEG terminal.
In the ideal case, the voltage at the coil would be the same a read directly across the battery terminals.  But, connectors and switches between the two points could lose voltage in transit.
This test measures the ability to deliver power to the coils.  But remember, electricity needs both a path to and from the destination device and the power source.
The coil Negative path to the battery is through the closed points to the engine case and the battery's negative cable connection to the engine case.

Cheers,

[afastman]

OK so I got down to the garage and unwrapped the number 4 cap.  The caps are slipped onto the wires and secured with the electrical tape.  Perhaps this is normal and I do not know what i am looking at, but it seems off to me.  The plastic cap has what I surmise is the resistor in one side and a long metal point which inserts into the coil wire on the other.  My take is that the part that attaches to the plug must be a resistor as the plugs re standard NGK D8EA plugs.  Here is what it looks like:

[TwoTired]

If the wire leads are stiff and hard to bend, they are likely the stock ones.  With the plug cap removed, look at the end of the lead. You should be able to see a clean center conductor wire in the center.  This is where the plug caps screw into to make a firm connection.  If the end of the lead is damaged, you can cut off  a 1/4 inch or so to renew the end and the plug cap should then screw on tightly.   This can only be done so many times before the wire then becomes too short. So, beware.  While you have the plug caps off measure the resistance from inlet to outlet. Should be 5K Ω +/- 10%.  (However, some caps are 10K ohm.)  Resistance of infinity means an open or bad plug cap, that should be replaced.  It appears that the rubber boots that seal between cap and wire have gone missing, and the PO has attempted to use black tape as a band-aid to seal water out.

If you can run the bike in a darkened garage, problems with leakage can be found along the ignition leads as visible arcing.  You want any sparks in the system to occur at the spark plug tip, not elsewhere.

If the engine is running rich, dark deposits will be made on the spark plug tips.  This will rob your ignition of power as the dark deposits are carbon, which is conductive and can siphon off electrical energy.

Don't forget to check the items in my previous post.

Cheers,

[afastman]

Where are the threads?  As far as I can see, the plastic is smooth and the metal point inside of it is smooth.  Also on the cable side there is some braided or twisted copper mushed to one side.  I can assume that is the "core" of which you speak.  I am going to spend a good day with the bike tomorrow (including the first go thru on the carbs).  I think with the new plugs and testing all of the checklist you gave me Two-  I should be in good shape. 

[TwoTired]

Inside the plug cap interface with the High Tension leads is a post with threads on it.  It's a coarse thread.  Kinda like a wood screw.  If you can't see them from an end on view, you shoul be able o feel them with a paper clip wire end, slightly bent at the end.

Can't imagine these threads wearing off, but, if yours don't have threads any more, I think I would replace them.  The screw post acts like an auger, drilling into the end of the wire lead to make solid contact wire the wire conductor and provide mechanical retention for the plug cap onto the ignition lead.

Good luck!

[afastman]

bumpity bump...

So layoff and holidays notwithstanding, I got down to the garage and set out to install a new set of spark plugs, determined to sort this from the easiest aspect first.  Good news is that the old plugs were well tan, not oily.  I got blue spark  (however it was not really bright) when testing the new plugs against the motor, so it might have just been that.  Now I have a new problem.  The number 3 plug came out a little roughly, but not too bad.  However when I put in a new plug, it goes about a twist nad a half-twist and an eighth and then I cannot turn it by hand any firther.  I can force it with a rachet, but am afraid to strip/cross thread the case.  I stuck my finger into the hole where the plugs go and it came out black and a bit grimey.  So my inclination is that there is some gunk that dropped into the hole.  Where do we go from here.  I feel like such a NEWB on this.  I was shocked at the gymnastics necessary to get the socket into the middle 2 holes and getting those out/back in.  took damn near an hour on #2.

[TwoTired]

Describe the tool you are using to remove/install the plugs.

[jtb]

Get an 18mm deep socket from Sears.  I use a 2" extension on mine.

[afastman]

exactly what i am using.  I do not want to force the plug in...is it possible there is gunk in the threads of the motor?

[afastman]

bumbity bump...

Anyone out there know how to clean the threads on the motor so the plugs can go in...or is there a different concern that I should be having right now?

[TwoTired]

Some people like to oil their spark plug threads.  This is tolerable with a steel plug in a cast iron head.  But, not with a steel plug in an aluminum head.  The temps get high enough to change the oil into a tarry glue like substance.  It often has a shear strength greater than the aluminum itself. 
This is bad. 
High temp anti-seize is the correct thread treatment for spark plugs.

I think you should find a small mirror and a flashlight to examine those threads for damage or simply crud build up.  If a PO used a too thick socket to start the plug cross ways, the threads are damaged and will have to be chased, if not redone with a hellicoil.

Forcing is bad.

Hopefully, you will only need to have the threads chased.

Cheers,