[LEGION]

Hello Ladies and Gents. I haven't been around the forum for some time since selling "Herbie" the 1980 CM200 a while back to a friend. I've since had an SL350 land on my lap and I'm working on getting it running and could really use some help. Here's the scoop.

I drained the gas tank and refilled it with 2 gallons of fresh 87 octane fuel. Removed both carb bowls and dumped out the old gas. A while back on a weak attempt to get it running I removed both carbs and gave it a good cleaning but this time around I didn't do this. That was probably 2-3 months ago.

With the choke on fully it fired up in about 5 kicks. Sweet. Purred like a kitten actually but then I realized only one exhaust header was getting warm. Left side was hot, right side was dead cold. With the bike idling (on the left cylinder) I removed the right side spark plug wire and promptly got zapped but I managed to stick an inline spark tester and verify that it was getting spark. Next I moved on to fuel. I sprayed starter fluid straight down the throat of the right side carb and saw zero change in engine speed or header temp.

The next place I went was either bad spark timing or valve clearances. The service manual I have states they should be .002" and .004" (I don't recall if those are intake or exhaust). The smallest shim I had was .006" so I rotated the crank to set each at TDC and verified the tappets were loose and attempted to put the shim gauge in the gap. No go. So they are all less than .006" and judging by the amount of slop I don't suspect they are less than .002" so I think bad valve clearances are unlikely. Perhaps someone here can shed light otherwise.

Next I did a compression test on both cylinders and they were right around 150 psi by the time I got tired of kicking. Manual states 150-170 is normal and since this was done fairly cold I called that a pass.

Then I opened the points cover and adjusted the point gap where the contacts open and close. Manual states they should be 0.3mm to 0.4mm so I adjusted them where the 0.3mm shim had very light drag and the 0.4mm caused visible opening to make it fit. Next I checked for spark timing by attaching a multimeter across one set of points and turned the meter to test continuity. I cranked the engine through its paces and rotated the whole plate until the points opened right at the F mark (which I think means the right side cylinder). In hindsight, I only did this for one set of points but I can't adjust them independently so was this okay?

I checked the spark plug gaps upon reinstallation and found them to be in spec. Manual said .028"-.032".

I buttoned everything back up and gave the bike a few kicks (took more than 5 this time around) but it fired up and alas... Still runs on only the left cylinder. Same symptoms. Has spark, starter fluid has no effect. No backfires no nothing.

Can anybody shed light on what is going on here? Is the right side carb flooding the engine and that's why it doesn't run and starter fluid (more fuel) has no effect? When I put the fresh gas in I watched the fuel go through the filters and made sure the flow stopped once the bowl got full so I know the float valve works. Maybe a float height issue?

Any help would be great because I'm stumped.

Thanks in advance.

-Harrison

 

[doode]

Has spark, or got zapped? Those are two different things.
Did you try new plugs? and caps and trim the ignition wire while you're at it?

 

[LEGION]

Has spark, or got zapped? Those are two different things.
Did you try new plugs? and caps and trim the ignition wire while you're at it?

Thanks for the reply Doode!

I got zapped in the process of removing the spark plug wire from the plug itself while the bike was running. I then placed an inline spark tester between the wire and the plug and saw a consistent flash. I didn't visually confirm there was a spark. I find it hard to hold​ the plug against the cylinder while kick-starting but it might be worth it just to triple check. I was using a spark tester like this.

http://m.harborfreight.com/inline-ignition-spark-checker-69014.html

While I had the spark plugs out I kept track of the left/right ones and compared them. The left side was dry and a light black. Right side looked a little wet and smelled like gas. Same gaps from left to right. Plugs are like new.

I should've swapped the plugs while I had them out just for good measure...

 

[doode]

I just reread your original post... You need to make sure the rt side points open at F on the correct stroke. Sounds like the left side is timed to LF, but the rt side timing needs to be set just as accurate. Check and confirm. You can adjust the open/close of each side separate from the plate

 

[LEGION]

I just reread your original post... You need to make sure the rt side points open at F on the correct stroke. Sounds like the left side is timed to LF, but the rt side timing needs to be set just as accurate. Check and confirm. You can adjust the open/close of each side separate from the plate

I can't adjust the spark timing independently since both sets of points are rotated when I turn the points plate. Or am I missing something? Nonetheless i should have done my continuity test on both sets just to confirm. Now that I think about it though I actually was testing the right side because I remember it was just plain F and T. Not LF and LT.

I should also pay attention to what's going on in the valves when I'm setting this because maybe it is off by 360 degrees. Previous owner "rebuilt it" so who knows. Hmm...

 

[doode]

You can loosen the top and bottom screw of each side and pivot it to open/close sooner/later.

 

[LEGION]

You can loosen the top and bottom screw of each side and pivot it to open/close sooner/later.

According to the service manual those screws are only for adjusting the point gap and not the point timing. Regardless I don't think I'm dealing with a couple degrees off. Otherwise I would be getting popping or at least some sort of heat coming from the pipe right? I'm wondering if the spark is a full 180 degrees off or there's something weird and I'm getting no spark at all. I need to remove the plug and visually verify a spark to be sure.

 

[Yendor]

The correct process is to Set the Left Side GAP as close to the middle of the point gap range as possible then time the left side.
The timing on the right side is then set by adjusting the GAP.
As long as the Gap is within range when the right side is timed walk away, it's done right.

To get any better you have to use a Timing light.

Still the same process.
Set the left then time the Right by moving the Gap. Double check the Gap is within range when timed.

If the Gap is not correct, - Find what the GAP is on the right by checking with multiple feeler gauges.
Then Move the Left Gap by Half by the out of range difference and follow directions above.

 

[LEGION]

The correct process is to Set the Left Side GAP as close to the middle of the point gap range as possible then time the left side.
The timing on the right side is then set by adjusting the GAP.
As long as the Gap is within range when the right side is timed walk away, it's done right.

To get any better you have to use a Timing light.

Still the same process.
Set the left then time the Right by moving the Gap. Double check the Gap is within range when timed.

If the Gap is not correct, - Find what the GAP is on the right by checking with multiple feeler gauges.
Then Move the Left Gap by Half by the out of range difference and follow directions above.

I'm going to start the process you described now just to be sure it's set right. In the meantime, do you see anything that's amiss? Still boggles my mind that it has spark and it has fuel but the exhaust pipe remains cold...

 

[LEGION]

Update:

I've set both point gaps to where a .308mm shim fits easily and a .406 causes noticable point movement when inserted. I've also rotated the crank while testing continuity over the point gaps and found the left side breaks continuity here:

And the right side breaks continuity here:

Both gaps are correct and the timing of the breaker opening is correct. Interesting enough, now I can't get the bike to run period. Not even on one cylinder. It's been hooked up to the battery charger and I've tried shots of starter fluid. No pops, no stutters no nothing. Also verified the blue wire goes to the right side ignition coil, yellow wire goes to the left side.

I am at a loss here. Anybody have some ideas?

Here is my current point setup.

 

[outobie]

PoinT gap is not critical so long as it's close

point timing is apsolutely critical

get the shop manual on tuning thenignition

ditch the meter and use a light or even better a strobe


In addition to your obvious timing issue you are likely loosing spark somewhere as well.

typical places are:

bad plugs
bad connections between high tension lead and plug boot
arcing points on poinTs cover

 

[LEGION]

get the shop manual on tuning thenignition

ditch the meter and use a light or even better a strobe


In addition to your obvious timing issue you are likely loosing spark somewhere as well.

typical places are:

bad plugs
bad connections between high tension lead and plug boot
arcing points on poinTs cover

I am using the factory service manual.

Both contact breakers open precisely at their corresponding F and LF mark. I cranked the engine over a dozen times and verified this. Just as the photos show.

What good would a light be versus testing continuity? It's simply playing a tone when the breakers are connected and stops when they open. A timing light (what I assume you're calling Strobe) would be of no use when the engine doesn't run correct?

What makes this an "obvious timing issue"?

I've tested for any improper grounds and all the way back to the ignition plug there is no grounded wires. Everything is grounded when the key is off, then goes away when the key turns on. Ignition coils look to be brand new. Spark plugs are brand new and gapped according to the service manual.

Spark plug boots appear brand new. I even clipped the end off the wire and screwed the ends back into the wire to be sure it had a good connection.

Is it possible to install any of this stuff backwards? Or perhaps the spark advancer is improperly installed? I think there is something fundamentally off here.

 

[Simo]

Have you checked the non firing side doesn't have a fouled plug? just getting power to the plug doesn't mean it's actually sparking at the gap
New plugs don't actually mean good.

 

[LEGION]

Have you checked the non firing side doesn't have a fouled plug? just getting power to the plug doesn't mean it's actually sparking at the gap

That is on my list to remove the plug and watch for a visual spark. I verified they are the correct plugs from the manual and the gap is to spec. I'm really wondering if the spark advancer is on backwards. I'm going to remove the points plate and verify that.

Sent from my Nexus 5X using Tapatalk

 

[LEGION]

I'm planning to follow this guy very carefully tomorrow morning.

In addition, I'm going to remove the points plate and verify this is installed correctly.

 

[LEGION]

Update.

I checked the spark advancer and it looks correct. The mark on the front lines 180 degrees from the key on the shaft. According to the second video I put in my previous post, that should be correct (read the comments. The guy said his was backwards in the video).

Next I set the points precisely. Exactly as the first video described. Spark happens at exactly the F and LF marks of the corresponding compression strokes. Reinstalled the spark plugs and the bike STILL won't run. Starting fluid has no effect. Choke on/off has no effect. I reinstalled both filters and airboxes and that had no effect. I am keeping the battery on a charger just to be sure it's charged.

I'm going to grab a shim gauge from work with finer shims so I can check the valve clearances properly but I have little hope that will fix it.

I'm really tired of this bike.

 

[LEGION]

Spark plugs look like this. The darker one came from the side that used to actually run. They are NGK B-8ES with the resistance cap removed from the top so it's just a threaded rod on top.

 

[Simo]

Have you confirmed they spark? The right one looks suspect enough that I'd put new ones in, especially if your having issue ,$5 to eliminate fouled plugs from the equation...
Also the tops are just a fitting not the resistor , the resistor is internal
View attachment 169194
B8es don't have any ( added) resistance , the 5kohm Resistor is in the lead cap ( you should check the lead caps as they tend to gain resistance over time.
BR8es are the Resistor plugs, you can use them but only if the lead cap is non resistance , otherwise you'll have 10kohm or more of resistance

 

[LEGION]

Have you confirmed they spark? The right one looks suspect enough that I'd put new ones in

I'm about to verify the valve clearances so I'll remove the spark plugs and visually look for a spark just to be sure. Inline spark tester shows a good consistent spark on both sides.

 

[turnsleft]

My 71 SL 350 was doing kinda the same thing, left side exhaust was around 450degs and the right was 112degs. put in a new batt and it seemed to run
pert good for a bit then again running on the left side with backfires coming from the right side. It would free rev but not move the bike very well?
I set the point gap and was wondering if the slides were swamped around as I couldn't get the idle speed to go up by turning the idle screw in or out.
Any the[one of] problem turned out to be the throttle cables were not timed. The left bank was speeding up and pulling the right side. I set them about 1/8"
of slack and took it for a ride best it has run, no back~fire at all. My 72 SL does the same thing[not so bad tho] so going to play with the 72 Monday.

Some thing to check any way.