CL350 - Carbs rebuilt, new ignition, won't run, huge backfires

so2002

so2002

Been Around the Block
Hey guys,

I'm really at the end of my wits on this one! Current issue: bike will not start. Doesn't seem to be firing at all. I have spark, but can't get even the slightest turnover.

Scenario:

I bought this bike last fall and rode around on it for a while. It had hesitation issues at 3k rpm. After doing a full carb rebuild, it worked for a while before temporarily dying (coils leaked wax). After replacing the coils, I took it out and had serious issues with misfiring. At one point, I had a 'gunshot backfire' and that was the last time it's worked. I couldn't get it to turn over, even with a new battery.

Things I have done:

Carbs - replaced everything with the complete overhaul kit from Sirus (last november)
Valve adjustment - was in spec, but made tighter
Compression test - tested at 150psi on both cylinders with the carbs on (I was supposed to take them off to get a true reading apparently) (This was before the gunshot backfire)
Ignition - replaced coils before the last time I had running, have now replaced the points and condenser too
Timing - Points are perfectly gapped. .014 on both, light turns on/off RIGHT at the mark

After timing, I charged up the battery and tried again, to no avail. After cranking and kicking for a bit, I've gotten 'gunshot backfires' twice, but nothing else. Tried swapping blue and yellow points leads, nothing.

On the wiring harness, I have a single green wire connector that isn't connected to anything. My horn is hooked up and working, my flashers and all lights work. Not really sure what it's for...

Any ideas guys? :-\
 
If you're getting spark (and it's timed correctly) and compression is good, it's gonna be an air/fuel issue.

After cranking things over for a while, are the plugs wet or dry?
 
Are you actually getting spark and/or fuel? For spark, you can try pulling the plug and grounding it against the head while you kick to see if its actually working. Should be a nice fat blue spark. For fuel, make sure it's flowing well through the petcock and filling up the float bowl to the proper height. If both of these have been done I'd go back to timing. Did you also take off the mechanical advancer when you replaced/gapped the points? If you did, it's possible to put it back on wrong, which will result in the engine being 180 degrees out of phase.
 
BarnBurner said:
Are you actually getting spark and/or fuel? For spark, you can try pulling the plug and grounding it against the head while you kick to see if its actually working. Should be a nice fat blue spark. For fuel, make sure it's flowing well through the petcock and filling up the float bowl to the proper height. If both of these have been done I'd go back to timing. Did you also take off the mechanical advancer when you replaced/gapped the points? If you did, it's possible to put it back on wrong, which will result in the engine being 180 degrees out of phase.
Click to expand...

:o...yes, I did take the mechanical advancer off (and shortened the springs). That would explain a lot, since I was under the impression that the light was going off when it should be going on! What is the correct orientation? I remember seeing a groove or something, and installing it the way I did for that reason.
 
Swapping the yellow and blue coil wires would have identified the advancer being 180° out.
 
oh...darn.

Well, I have gas in both fuel bowls, but I haven't verified float level. I measured within spec when I rebuilt the carbs. Not sure if the plugs were wet, I assume they were because of the huge backfiring, but I'll verify that.

As for spark, yes, I am getting it. When cranking the motor and holding the plugs against the engine, I see blue sparks on both plugs.
 
Update:

After doing some cranking (without and with throttle), I noticed that the plugs are dry.

I pulled the fuel bowls, which both had gas in them. Both sides have a nice flow of gas when the floats hanging, which slows and stops as they are held up. (Attached pic is the fuel level in 1 of the carbs when removed without draining. Is this too low?

fBpapXT.jpg


I assume this means that I have carb issues and will have to remove them from the bike (again)? Check float height? I just put all new brass in there in November.
 
Sonreir said:
If you're getting spark (and it's timed correctly) and compression is good, it's gonna be an air/fuel issue.

After cranking things over for a while, are the plugs wet or dry?
Click to expand...

I agree, I'm going to say you're running far to lean hence not being able to start and the backfires. I also think your intake valve could not be fully closing, I'd Pull the head and kick it over to see if the valves open and close properly.
 
If valves aren't fully closing, then you'll have a compression issue (which is why I always recommend checking compression when you have starting/running issues).
 
Sonreir said:
If valves aren't fully closing, then you'll have a compression issue (which is why I always recommend checking compression when you have starting/running issues).
Click to expand...

I ran a compression test back in November (back when the bike was still running) and got ~150psi on the left and ~130psi on the right. I will try again though, it is possible something happened.
 
Compression Tested last night:

150 PSI Left
138 PSI Right

While rechecking my timing, I noticed that my bike was lighting up on the wrong stroke (not after compression, (thanks for the "put finger over cylinder tip")). Realized it was because I rebuilt the Mechanical Advancer the wrong way (middle piece was 180'd, as mentioned). Didn't get a chance to put it all back together and start it up, as it was already Midnight, but I will do so asap.
 
One thing that I noticed:

The Valve Lash Adjustment screw for the left side exhaust port spins. The others all have well defined start/stop points that limit the travel of the valve. The one in question spins past, and the valve just goes up and down. When I lock it down, it does not move. Could this be causing my problems?

index.php
 
You must log in or register to reply here.

DTT Light or Dark

  • DTT Light

    • Spread the Love

    Back
    Top Bottom