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Discussion Starter · #1 ·
93 1100. Cobra drags, cobra jet kit, K&N air filter.

I went to a 45 from a 42 pilot because my AF screws were at 4 turns out. Currently screws are at 1.5 turns out. Some popping, so I'm going to go another 1/4 out soon.

Anyway, bikes runs great. Couldn't be happier with the throttle response all through the range. Plugs look decent too.

However, I have this odd intermitten starting issue... It used to only do it when hot, but now it did it to me this morning. I go to start the bike and it only turns over. Starts to puff a little, so I crack the throttle open to lean it out, fires up and away we go. I thought maybe my choke was hanging open a little bit, but it doesn't appear to be. Anyone have any ideas? Someone mentioned once maybe a weak float valve, but then wouldn't I have gas in my oil and maybe even hydrolock? (I have neither)
 

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Sounds like too rich on the starting circut. Could be the idle is too low. IMO, go back to the 42 jets, set it at 3.5 turns. You will have popping, Drag pipes POP, Cobra drags seem to pop even more. Either add baffeling to the exhaust or more restrictive airfilter maybe both to reduce the popping. You might have to live with some pop with that exhaust and intake setup.
You could try adjusting the float level, maybe hone the float valve seat and Replace float valve. Weak float valve wont dump the excess in the crank case, bowls have an overflow tube, excess will dump on the ground or evaporate. You get gas in the oil on these bikes, main cause would be fuel getting passed the rings or valves, maybe through the airbox.
 

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Discussion Starter · #3 · (Edited)
Too low of idle will cause rich starting? I'm been tinkering with the idle alot... When cold the bike will sometimes stall out, but when it's warm the idle is fine. If I set the idle for when its cold, it's too high when warmed up. I need a tach....

I turned my screws another 1/4 out and the popping seems to have gotten worse... I'll try the other way.

As a side note, I added a little seafoam to my tank last night... now, the additives in there might cause it to run a little different too, right? Also, with the ethanol free 92 octane I get 0 popping. None. Nadda. In first nearing redline and snapped throttle shut to almost a stop and not one pop. Problem is, I don't always have access to this fuel...

Why do you suggest the smaller pilots again? Couldn't I just tighten my AF screws down to accomplish the same thing (unless there is still a difference between 42 3.5 turns out and 45 1/2 turn out, but I would hope there would be some overlap)

Also, is there a good diagram of our carbs around here? I'd love to see one to see how the circuits all work.
 

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I'm Guessing, now.... Because you've been fighting the pop for a while. And are now having rich fuel sounding issues. Maybe you have gone an little too rich somewhere. Trying to get rid of a pop that can't be removed, through carb adjustment alone.

ALL adjustment and tuning should be done with warmed up motor. Cold idle and warm idle should be different. Without using the choke, the warm idle should be higher than cold idle. Thats the purpose of the enricher choke. If I set my idle cold to say 1000 rpm, when warm it will be at about 200 RPM hgher. If I set it warm it will be below 750 and need some choke to start.
 

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Discussion Starter · #5 ·
what kind and how do you use your tach? ( or do you have one installed?)
 

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No tach, my tach is my ear and butt. I set the idle to where it is smooth but not racing. When tuning I start my Jeep and then, by ear, set the Shadow to a little faster. The Jeep idles at 750-850.
 

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Discussion Starter · #7 ·
So, what you're saying is having the idle set too low I am causing it to be rich? I guess when you adjust the screw you are closing the butterfly, which allows less air. hmm.... seems backwards at first, but does make sense now.
 

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So, what you're saying is having the idle set too low I am causing it to be rich? I guess when you adjust the screw you are closing the butterfly, which allows less air. hmm.... seems backwards at first, but does make sense now.
Exactly. Throttle, Idle screw and Sync screw all affect the Butterfly ONLY, thus only the air side. The rest AF screw, choke, jets and floats affect the fuel side. Vacuum opperates the slide and needle jet, this affect BOTH air and fuel of the AF Mixture.

Can be confusing if you fall back into the Old School or Car mode of thinking. Where a throttle pump or valve may be part of the system and the CHOKE actually chokes off air flow instead of adding gas.
 

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Discussion Starter · #9 ·
So, when I back my AF screws out (add fuel), my idle increases, so I turn down the idle some more (removing air). So, maybe I'm double counting my richness, causing the goofy starting problem, and just maybe the popping. Before I leave work I'll go 1/2 turn in on my AF screws (I now keep a little screwdriver with me :) ), which will put me 1/4 turn in from where I started yesterday and adjust the idle properly. Hopefully I just need some tinkering and adjusting, not another trip to carb removal land!
 

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Have you checked sync, if so when and how????
 

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Discussion Starter · #11 ·
yeah, but it was about 2 carb removals ago. I have a set of vacuum gauges I used on my old KZ in-line fours. It was spot on. The kit came with the little adapters that thread into the intakes.
 

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I'd try syncing. I would also use an old school, u-tube manometer balancing rig. $1.55 Carb Sync Tool by Marty Ignazito. I also have vac gadges and mercury sticks. Example if I use the homemade manometer after syncing with the gadges or sticks first. Sync will still be off using on the U-Tube by about 16", ATF fluid in the gadge. Spec is to balance within 1.5" or so, of mercury. Vacuum pressure at 1" of mercury is the equivlent of about 20" of water, and 16" of ATF.
 
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