Author Topic: Air/fuel mixture problems after cleaning air filters. Need some help!  (Read 1272 times)

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Offline mlumsden

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I'm newto the forum and have had my 76 CB550 for about a month.  I knew it was only a matter of time before I buckled and had to ask for help on here!  So thanks in advance for taking time to look, here goes:

I cleaned the air filters (pods) put on by the PO.  They were really dirty.  Now, all clean, dried and oiled, I put them back on.  Assuming that the PO already had the carbs adjusted for these filters, I figured they would go back on and the bike would run again, but it doesn't!  The air mixture screws were set 2 turns out.  I tried screwing them in in half turn increments to enrich what I figured would now be a lean mixture due to better air flow and nothing is working.  Bike will run choked with a lot of throttle but will not idle.  I should add that the bike was not running perfectly to start; idle was only good around 2000rpm and I could only lower the idle slowly as the bike warmed up.

Sound familiar to anyone?  Could I have enriched it too much and fouled some plugs? Air leaking in somewhere?  If any of the CB gurus can enlighten me, I would much appreciate it!  If pictures would help let me know.  Thanks!
« Last Edit: May 03, 2013, 04:38:54 PM by mlumsden »
1976 CB550

Offline Reganator

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I've been dealing with some issues like this myself.

Are the pods the only thing that isn't stock?  What brand are the pods? 

If you want to check for leaks around the boots, you can use starter fluid or a little propane torch unlit and listen for a surge in idle. 

However, it sounds like the first thing you want to do is start pulling the plugs to see what they look like.  Your post doesn't seem to include many other indicators as to why you're thinking rich.

It would also be useful if you were to remove one of the bowls from the carbs and find out what jet sizes you have.  Shouldn't be hard and I'd think you could leave them on the bike.

Basically, you're going to have to dig a little deeper and get some more information up here to get some suggestions pushing you in the right direction.  As a new SOHC 4 owner myself, I can tell you that you're going to need to get comfortable getting your hands dirty or you're going to need to find a good mechanic.
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Stock airbox

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Offline scottly

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How did you clean and oil the filters? Are they foam or a mesh style like K&N? Too much oil can cause the motor to run rich. As previously stated, check your spark-plugs to determine whether you are too rich or too lean.
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Offline mlumsden

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Thanks guys.  Reg, I pulled the 1 and 4 plugs (my 18mm socket won't fit to get 2 and 3 out) and they were pretty sooty and old looking, but that's coming from an inexperienced judge of spark plug character.  I'll post pics of them later when I can.  Scottly,  they are the spongy type, Unifilter to be specific.  I cleaned and oiled with a K&N kit.  I tried to go light on the oil because of the easy saturation of the spongy filters, but maybe I still over oiled?

At any rate, new plugs and a good clean and sync for the carbs were already somewhere on the to-do list.  I'll update some pics of the plugs & filters, and get the numbers on the jets in the next day or so when I get into the carbs.  Any recommendations in the mean time?  I had thought about giving it a go without the filters on but I wasn't sure if thats risking too much.  Thanks guys!
1976 CB550

Offline Reganator

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Yeah, work on geting some pictures posted of them, but there are also resources online that will show you what good / fouled / rich etc. plugs look like if you google them.  You're going to need to get on top of ordering that tool for your plugs soon as well.  I understand Craftsman sells a thin walled 18 mm socket that works.  You could also look for the Honda OEM tool online.  It's available from a few sources, and it's really your best bet for working with the plugs.

As for running it, if it's running rich it's going to foul your plugs but aside from that and lousy gas mileage I'd imagine it's ok.  On the other hand if it is lean it may overheat and you'd want to avoid riding it much like that. 

Pull those carbs apart soon and see what you have jet wise.
Frankenbike CB750: 
71 K1 Frame
72 K2 Engine
75 F0 Carbs:
     #40 slow jets
     #105 Main Jets
     Stock needle and settings.
My-neighbors-love-me-Kerker 4 into 1
Stock airbox

The best way to make a small fortune on the stock market is to start out with a large fortune.  Trust me, I'm an actuary.

Offline dave500

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youve only had this bike a month,go right over the ignition before you tinker with the carbs!

Offline HondaMan

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Thanks guys.  Reg, I pulled the 1 and 4 plugs (my 18mm socket won't fit to get 2 and 3 out) and they were pretty sooty and old looking, but that's coming from an inexperienced judge of spark plug character.  I'll post pics of them later when I can.  Scottly,  they are the spongy type, Unifilter to be specific.  I cleaned and oiled with a K&N kit.  I tried to go light on the oil because of the easy saturation of the spongy filters, but maybe I still over oiled?

At any rate, new plugs and a good clean and sync for the carbs were already somewhere on the to-do list.  I'll update some pics of the plugs & filters, and get the numbers on the jets in the next day or so when I get into the carbs.  Any recommendations in the mean time?  I had thought about giving it a go without the filters on but I wasn't sure if thats risking too much.  Thanks guys!

OK, you're scarin' me...the K&N oil will plug up a foam filter in a drop! Wash them out again. With foam, I usually recommend to stop at the point: wash them out and dry them, don't oil them again. Reason: they are too close to the carbs, and aside from the way they SERIOUSLY disturb the airflow (meaning: you will never get it tuned to run right without the stock airbox back in its rightful place), they will wet themselves from the spitback of the carbs in about 50-100 miles. There won't be much need to oil them more than that. ;)
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Offline mlumsden

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OK, you're scarin' me...the K&N oil will plug up a foam filter in a drop! Wash them out again. With foam, I usually recommend to stop at the point: wash them out and dry them, don't oil them again. Reason: they are too close to the carbs, and aside from the way they SERIOUSLY disturb the airflow (meaning: you will never get it tuned to run right without the stock airbox back in its rightful place), they will wet themselves from the spitback of the carbs in about 50-100 miles. There won't be much need to oil them more than that. ;)

Man, I wish I knew that before getting into it.  Thanks and good to know though, looks like I'll be cleaning them out again!  I got a new set of plugs too.  Just waiting on my thin walled socket.

1976 CB550

Offline mlumsden

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Hondaman, you were right!  That oil must not be intended for the foam filters then?  Anyway, lesson learned, thank you guys for the insight, I'm sure I'll need it again when I get a little deeper into the thing!  I got the new plugs in too.  Here are the pics of what I was working with.
1976 CB550