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Discussion Starter · #1 ·
Okay so here's the scoop:

73 CL350, SL350 carbs (non-CV), open exhaust, K&N filters. High 160's in both cylinders, good spark, full charge on the battery, static timing set to spec, proper points gap, etc.

Both carbs are running rich, possibly need to run a smaller jet - using 120 right now as that's what was in the carbs when we tore them down during the rebuild. Needle is set 2nd notch from the top.

Problem is, the left carb would lean out, which seemed odd when we know damn well the tune is pig rich. Checked the fuel line for kinks and noticed the filter wasn't filling up with fuel. Pulled the line form the carb and fuel flowed fine. Put the line back on, and it'll flow fine but then we'll notice the filter is half empty and just barely trickling from the tank. That's when the carb leans out. To complicate things, the left side will run so rich that it flames out, then when the fuel line appears to be empty, it'll fire again until it loses fuel completely.

Frankly, I'm baffled. I don't want to drop the jet size until I know the timing is set but I can't really do that until I figure this out, either. Every time I pick up the timing light this carb tells me to take a piss.
 

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Sensei
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One Question first....... How did you mount slide valve SL carbs on a CL engine?....(The ports are different sizes and different bolt spacing/angles)

While I await that answer ...(I'm assuming a K2 or later SL head on the engine)... It sounds like the K&N filters are too restrictive (small) and the float settings are wrong.... What did you set the floats at?
 

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Discussion Starter · #3 ·
The carbs are mounted using what I assumed were the factory rubber couplers :?



You can kind of see the mounts in this picture:



If this is in fact an SL head then that's news to me.

One more thing, we actually removed the pod filters to eliminate them as the culprit and that didn't seem to affect it much, if at all.

Concerning the floats, my brother is helping me out since he knows more about carbs than I do. I'm really more knowledgeable when it comes to EFI. The bike is currently an hour away so I can't look at everything to tell you where it's at, but he said they were where they should be when we were working on it Saturday.
 

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Sensei
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OK then.... That could be the issue (pix weren't adequate to determine)...... CB and CL and early SL intake tracts are for 28mm CV carbs (28mm venturi).... The later slide-valve type SL carbs that you have are 24mm venturi and would have the "flow" disrupted by the upsize "step" .... A/The later SL heads (that took the 24's) had a smaller intake tract size that matched to the carbs.......The vacuum differential could cause "gulping" (gas floods at low throttle openings) and lean-out at ~1/3 open and above


Remove a carb and manifold and measure a port opening........Let us know......
 

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Discussion Starter · #5 ·
I can't measure the ports until this weekend but it wouldn't make sense if the right side carb isn't giving me this problem but the left side is. It seems to me if it was the intake port size, both carbs would "gulp". Also, the fact that the fuel line flows freely until we put it on the carb inlet, it tells me air or some other sort of obstruction is blocking the line. In that one pic you can see the filter is only partially filled while the other filter is full, well that's what it does until we remove the line from the carb, then it flows just fine. Once we put it on the carb, it drains out and acts like something is blocking it.
 
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