Okay, got most of the bike back together but no spark GT550

[bobotech]

At the point where i am checking for spark on my 75 GT550.

I cleaned everything up, got the engine freed up, rebuilt the carbs/petcock, and fixed the wiring.

Well i think I fixed the wiring. When I turn it to run, I can hit the starter button and the starter spins the engine, neutral light works, turn signal light works but they don't blink (i assume flasher), the headlight and taillights work, brake light works.

The gear shift indicator does not work and I am getting no spark. I really haven't done anything to the points other than clean the snot out of everything with brake cleaner and left it as the settings it was when it was parked.

I figured that should be enough to at least see a spark on one of the cylinders. No matter which spark plug I check, I get zero spark. I have all 3 plugs out of the cylinders for now.

Where should I start? Even though I am 43, this is the first vehicle I have ever had that had points. Well not exactly true but back in 85, I had a 75 CB750 but it had been converted to electronic ignition.

[smoketriples]

eh, I'm on the high side of 50 and no smarter trust me .

Check you are getting juice at the coils. Doesn't hurt to unplug and clean with crc 56 all of the plug blocks under the left side cover.

You can also pull a plug out and hook it to the spark plug wire and let the plug ground it's case on the engine, then spin it over and see if there is a spark.

[jabcb]

With the plugs out of the cylinders and grounded to the engine, do you get a spark at the plugs or points when you manually operate the points with a screwdriver?

For each points, check the voltage with the points open and closed.

If you got nothing, then check the voltage for the orange wires that lead to the coils.

[bobotech]

Awesome stuff.

I currently have all 3 plugs out of the cylinders. I have the plugs in the boots and they are grounded to the engine head for testing purposes.

So I shall manually operate the points while the ignition is on and see what happens.

Where and how do I check the voltage for the points (open and closed)?

[tz375]

Switched 12v arrives on the Orange line. I'd start by testing the orange leads at the coils to see if you have power at the connector with the coils disconnected. That will determine if you have power that far in the circuit. If not, trace back to the kill switch and form there back to the ignition switch to see where the electrons are leaking out.

Turn on the ignition and don't forget the kill switch and use a flat bladed screwdriver to flick the points open.
If a point set is closed, flick the points open and see if one plug sparks or if the points spark.
If a set of points is open use the screwdriver blade to touch both points (the fixed and moving parts) and then remove the screwdriver and a plug should spark.

[bobotech]

Just a small update, I dissembled my start and engine stop switch assembly and cleaned it out. i was having small issues with the switch and just felt like cleaning it out anyway. it is working better but still no spark. its raining out so I'm not really going to do much more diagnosis on the bike today.

Also I uploaded a translated version of the nice color GT550 wiring diagram:

[bobotech]

Well I went out there and checked, I am getting 12 volts to each of the 3 orange wires going to each coil. So the wiring is good up to there.

Next step is to manually trip the breakers and see what happens.

[bobotech]

Okay, tripping the breakers manually worked. If I touched both of the contacts and then let go, I got a fat spark at the plug. But none of the breakers are tripping unless I manually short then release the breaker with a flat bladed screw driver.

The breakers themselves are not working. Not sure if I can clean them or need to get new ones, but at least I know where the problem lies. I'm kind of glad that its not a wiring problem.

ugh, now to adjust the points.

[Cliff]

Give each of the points contacts a quick cleaning with some fine sand paper/emery cloth. You don't want to remove any material from the contacts, just clean any oxidation off of the face of them. Then make sure they are clean and DRY. She should start now!
Cliff.

[H2RICK]

quick cleaning with some fine sand paper/emery cloth

VERY fine......as in 1200 or 1500 grit. The tungsten on those points is VERY thin and it's quite easy to grind it off if you're not careful.
I'd use an unshiny-surfaced business card to clean out any crud instead of emery. That way you won't take a chance on completely wrecking the contact surfaces. It's amazing how abrasive a plain business card can be.

[Coyote]

bobotech, While you are in there, remove the 3 screws that retain the points plate and swing it off to the side. Carefully inspect the points cam for corrosion or pitting. If that is detected, remove the nut and extract the cam. Stick a bolt through it and a nut. Chuck the bolt in your drill motor. Spin it and polish th surface with scotch-brite. Put the cam back in place on the shaft and retighten the retaining nut.
Now before putting the points plate back on, put 2 drops of oil on the felt wiper. Put a VERY light coating of grease on the cam. Not too much as you don't want it to sling out and get on your points.
This is important and only takes a few minutes. If you leave it rough and dry, you'll be setting the timing every 100 miles as it will quickly grind away the fiber cam followers.

[bobotech]

How do I remove the cam? It seems to be frozen on there.

I removed the nut and it won't budge. I have the side cover completely off the bike currently. I went and removed the tachometer drive gear assembly and put the nut back on the cam bolt and hit it firmly trying to loosen the cam drive but it refused to break free.

Any suggestions or do I just hit it harder. I have the nut flush with the bolt tip surface so I won't mushroom it over.

[Coyote]

The shaft that the cam is on is straight, not tapered. So whacking on it won't do you any good. The cam is a slip fit on the shaft, so you must have corrosion between the two. I'd try some penetrating oil and let it sit fo a while. Then heat the cam with a propane torch and everything might just drop out (cover oit's back and proped up).

[Coyote]

OH WAIT! The shaft can't come out the back side because of the pin that the propeller sits on will prevent that. Be careful whatever you do as right behind the pin is a seal and some bearings. I don't remember how much room is in there. Is there room for a puller if you pull from behind the propeller? If you mess up your propeller in the process, I have a spare I could send you.
At this point, maybe the best bet is rig a way so the shaft won't turn. Cut a strip off your scotch-brite pad and use it in a 'shoe shine' fasion.

[bobotech]

Well I fixed it. LOL

I went and kept on tapping it until I realized that there was the pin in the shaft that was preventing it from coming out.

HOwever I had already damaged the pin by whacking on it so I just said "screw it" and whacked it really hard to free everything up. I destroyed the pin but I wasn't worried about that. I managed to get the cam off the shaft and I pulled everything apart. I'm glad I did too, there was a bunch of corrosion in everything.

I cleaned up the shaft, got rid of all the rust, smoothed out the bunged pin hole where I damaged it. I then got a 3mm drill and drilled a tad deeper in the pin hole (the pin was 3mm). I then cut off a short piece of the 3mm drill for a replacement pin. Cleaned up the cam as best as I could. Used scotchbrite and emery cloth and put the cam on a bolt and spun it to clean it up as best as possible. The last step I did was to use my dremel with the polishing bit on it and put some rouge on the polishing pad and then spun the dremel at med speed while holding it against the cam which I spun using the drill. Got it quite shiny and clean however there still is a lot of pitting but it is smooth, no rough edges but still lots of valleys.

My pin hole held the new pin perfectly fine, I was pleased how it held up.

I hope it will work for a while until I get a replacement cam that isn't as badly pitted as mine.