Is this just a charging issue? Or something more?

[bennecc]

Before I forget, this applies to an '81 Special II with Pamco.

My bike hasn't been charging; after poking around w/ the multimeter I came to the conclusion that the brushes just need replacing (fingers crossed). I ordered a set but they won't be here for a few days.

In the mean time I decided to try to do some mild carb tuning. I started with a freshly charged new-ish battery. Today I started up the bike on full choke no problem. I was messing with the idle and waiting for it to heat up when it died. It probably ran for 1-2 minutes. Then I couldn't get it to start. A couple hours later it started up and did the same thing. When I try to start it after it doesn't sound like it is close to starting. It does kind of sound like a hiss as I kick it over (I'm not sure how do describe that sound, its nothing drastic, just something I noticed). Occasionally it will nearly catch, other times a loud "crack" and a bit of smoke out of the air filters (I think that's where the smoke comes from). I pulled a plug (new) and grounded it to the head and kicked it over.....definitely more of an orange spark than a blue one. Plugs were a bit black and wettish so I cleaned them off. I checked voltage on the battery and it was around 12; that seems like plenty to get a good spark, right?

Anyways, I ran out of time and left it after that. Anyone have any ideas what I should be checking? Could all this be related to the bike not charging? (I put the battery back on to recharge)

Also, I had adjusted the valves a few days ago and found all 4 of the nuts either backed waaay off the tappet or completely off and rattling around. Today I checked again and one of the nuts was backed way off again! It was the first valve I adjusted a few days ago so I think I must have not tightened it very hard as I hadn't yet realized all of the nuts were so loose. Anyways, I retightened it and I'll keep an eye on it. Anyone have that happen to them?

 

[pamcopete]

bennec,

Well, if you have an ignition problem, it may be that your advance rod is binding, throwing off the timing and making it difficult to start.

Start by looking at this video which shows how your advance rod is supposed to snap back, indicating that it is not binding and that the springs are OK.

 

[bennecc]

Thanks Pete. I checked and that doesn't seem to be the problem, thank goodness. I had the hardest time getting it not to bind when I installed the advance rod for your ignition.

 

[bennecc]

I worked on this problem a little more this evening. Used a fully charged battery and kicked it over a few times; it wouldn't start but I did at least hear it making a weak attempt a couple of times. Then I took the air filters off and sprayed some starter fluid in the carbs. It took about 3 kicks but then it started up and ran until I guess it used up the starter fluid and died.

So, I was thinking it must be a carb issue. Tore down the carbs and did my best to clean out all the jets. I really don't know anything about these things but I consulted with the carb guide .pdf that is always referenced on the forums. Everything seemed clean. Put the carbs back on the bike and........it won't start. It doesn't even sound like it is close.

Can anybody give me some ideas of what I should be checking? I'm stumped.

 

[pamcopete]

Are the vacuum barbs either plugged or connected to the pet cock? If left open, the air that is sucked in makes the mixture too lean to start.

Is there gas in the tank? (Don't ask why I ask this question.)

 

[bennecc]

the vacuum barbs are plugged. the tank is off and i'm using a bottle i hooked up; i'm sure the carbs are getting gas since there's fuel in the bowls when i drain them.

 

[bennecc]

Argh! Anyone want a piece of @#$*?? I'm almost ready to get rid of it.

I've cleaned the carbs twice, especially paying attention to the pilot jet (the one under the rubber plug, right). The mix screws are 3 turns out (1981 stock carbs). Battery is fully charged. Advance rod is not binding. Cold compression test of 120-125 psi both sides. Pulled plugs out to check the spark; I have no point of reference so I'm not sure if it is "fat" or "thick" like it is supposed to be, but there is spark.

After it sits for a couple hours it seems to almost start on the first kick. After that it doesn't do much except wear me out. I got it to catch for a few seconds with starter fluid at one point; when i tried it later on I got nothing.

PLEASE HELP!!! Somebody must have some ideas that I haven't had, considering I'm completely new at this!

The bike was running just a few days ago. I don't know what could have changed. Is this how the bike would act (i.e., not even close to starting) if there was something in the carbs somewhere? Is there somewhere else besides the pilot jet I should be playing extra special attention to? (the carbs were recently rebuilt so they are pretty clean, plus as I said I've been through them twice today)

Is there a video somewhere of what the spark should look like? Could it be a weak coil? How do I test the output of the coil?

What would the symptom be if there is gas in the crankcase?

 

[pamcopete]

bennecc,

Perhaps the clue is "the carbs were recently rebuilt so they are pretty clean, plus as I said I've been through them twice today". Obtaining matching parts for these old carbs is problematic. Even the kits are sold with the caveat that the parts may or may not match what is in the carb. Even if rebuilt by a "professional" having the incorrect parts installed during a rebuild is very common.

You could, therefore, try reinstalling the original parts, especially the jets.

 

[bennecc]

Sorry, maybe I misspoke. I thoroughly cleaned and refurbished the carbs myself, replacing only the float valves, gaskets, rubber plugs, etc. I know them to have been working fine as of two days ago. Then I have pulled them and "cleaned" the seemingly clean carbs twice more since then.

 

[pamcopete]

bennecc,

Well, lets revisit the ignition. You can use a timing light to do a rough check of the timing even if the engine does not start. Just make sure the battery is charged up and clip on the timing light. Turn the engine over and look at the timing marks to see if the timing is at least in the ball bark as the engine turns over.

If it isn't, then think about the installation of the PAMCO. There are three locating pins involved. One for the PAMCO rotor, one for the slotted disk that engages the weights on the advance side and the third locating pin locates the advance mechanism plate. It's the third one that often is overlooked.

There are pics of all three pins in the advance installation instructions on the web site www.yamahaxs650.com

 

[bennecc]

Pete,
Thanks for the reply. I had really high hopes about this from your link:

"Note: There is also a pin in the advance mechanism plate used to secure the locating pin that sometimes protrudes and interferes with the nut that holds the advance mechanism in place. File this pin down as well."

That pin did appear to be interfering with the nut so i ground it down, but it didn't seem to make a difference.

I don't have a timing light; I'll have to ask around and see if somebody has one I can borrow.

Here's a video clip I just took of the spark as I kick it over. Not sure how much you can tell from it considering the quality:

 

[pamcopete]

bennecc,

This is the locating pin I was referring to in my last post:

Here is a test procedure to test the PAMCO without having to turn the engine over or start it:

1. Use a voltmeter and check for battery voltage on each of the red/white wires with the key and kill switch are turned on.
2. The dual output coil has to have both spark plug wires connected to a spark plug at all times.
3. To test for spark, connect one of the spark plug wires to a spark plug that is grounded to the engine.
To test for spark without having to turn the engine over, do this procedure:
1. Remove the PAMCO rotor.
2. Remove the locating pin in the advance rod.
3. Reinstall the rotor, but without the pin.
4. Replace the nut holding the rotor on loosely. This will allow you to spin the rotor to produce a spark without having to turn the engine over.
5. Connect one of the spark plug wires to a spark plug that is grounded to the engine, but not installed in the engine.
6. Make sure that the other spark plug wire is connected to a spark plug in the engine.
7. Turn on the ignition switch and the kill switch.
8. Spin the rotor while looking at the gap in the spark plug for a spark.
9. Turn off the kill switch and the ignition switch.

When you put the pin back ion, here is the positing for the plate for the initial start, but you will have to get a timing light to set it more accurately.

 

[nj1639]

Gas in the crankcase? Floats not working properly.