Topic: 1974 CB550k Boss Maroon

[brett_bike]

I have never placed much value in reading plugs after a “ride” because their condition does not tell you position of throttle that the state is occurring. It is best practice to start clean, fresh plugs, and do a plug reading at idle. Then again at WOT and chop the motor. Pull the plugs roadside and snap pictures of them. Then return to the garage to make any adjustments needed.

From looking at the picture, I’d say your fuel level is wrong on the carbs if all other settings are equal. If the bike is running strong, that somewhat rules out ignition issues, but not entirely.

I plan to pull the carbs again and verify everything.

Thanks


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[brett_bike]

I have never placed much value in reading plugs after a “ride” because their condition does not tell you position of throttle that the state is occurring. It is best practice to start clean, fresh plugs, and do a plug reading at idle. Then again at WOT and chop the motor. Pull the plugs roadside and snap pictures of them. Then return to the garage to make any adjustments needed.

From looking at the picture, I’d say your fuel level is wrong on the carbs if all other settings are equal. If the bike is running strong, that somewhat rules out ignition issues, but not entirely.

Thanks for all the input calj737!  I really appreciate all the assistance.

One thought/question…

Would the fuel lever still make the bike stumble  at approximately 1/4 throttle? 


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[calj737]

If you’re asking about fuel level in the bowls, then I’d expect it to manifest itself as a problem in more than just 1/4 throttle. See if the attached helps provide some insights:

[brett_bike]

I’ve seen those.

Ramon thoughts in no particular order…

I’m wondering if the fuel lever would cause the plugs (1 & 3) to foul.

I’d imaging if it were spark it would be 1/4 or 2/3.

I’ve been searching the forum and came across an article that mentioned the needles being wore down, possibly from cleaning I guess, and allowing more or less fuel to pass.

I’m going to dig back in to make sure I didn’t miss something inside the carbs and inspect the needles and emulsion tubes. I feel like other than fuel level in the bowls that’s where I should focus.

Also, I’ll be doing a WOT plug chop in the next couple of days and report my findings.


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[calj737]

Also confirm the needle position for each carb.

I haven’t looked back, did you do Clear Tube method to confirm fuel level in each carb?

[brett_bike]

Needle position confirmed #4 from top (stock)

Yes, clear tube confirmed fuel level.


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[calj737]

Needle position confirmed #4 from top (stock)

Yes, clear tube confirmed fuel level.


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Should be 2nd from top (if you consider the tip the bottom). If you’re in the second from the tip, you’re too rich.

[denward17]

Needle position confirmed #4 from top (stock)

Yes, clear tube confirmed fuel level.


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Should be 2nd from top (if you consider the tip the bottom). If you’re in the second from the tip, you’re too rich.

I had to go to the center position to lean my '76 550 out some on the bottom end.  When I tore into carbs they were in the 4th position from top, or 2nd from tip.
The bike runs much better when at operating temp, but doesn't run quite as well when cold.  I now have to fiddle with the choke a little bit more, which I am ok with.  I guess I made it a little more cold natured.

Don't know if it matters, but I also installed new Honda needles/emulsion tubes.

[calj737]

I had to go to the center position to lean my '76 550 out some on the bottom end.  When I tore into carbs they were in the 4th position from top, or 2nd from tip.
The bike runs much better when at operating temp, but doesn't run quite as well when cold.  I now have to fiddle with the choke a little bit more, which I am ok with.  I guess I made it a little more cold natured.

Don't know if it matters, but I also installed new Honda needles/emulsion tubes.

At center position,  probably rich at WoT if you’re induction setup is stock. You should be second from top, fourth from tip. Moving to the middle enriches the carbs (raises the needle with throttle increase, allowing more fuel). Whomever had it second position from tip was either running pods, or was errant in their assembly.

[grcamna2]

Needle position confirmed #4 from top (stock)

Yes, clear tube confirmed fuel level.


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Should be 2nd from top (if you consider the tip the bottom). If you’re in the second from the tip, you’re too rich.

I had to go to the center position to lean my '76 550 out some on the bottom end.  When I tore into carbs they were in the 4th position from top, or 2nd from tip.
The bike runs much better when at operating temp, but doesn't run quite as well when cold.  I now have to fiddle with the choke a little bit more, which I am ok with.  I guess I made it a little more cold natured.

Don't know if it matters, but I also installed new Honda needles/emulsion tubes.

Den,I've installed some special thin washers to go about a 1/2 step(+ or -),rather than a complete clip notch;it takes a little looking to find the washers that will be just right.

[brett_bike]

I have it on clop #4. I was under the impression that was stock. 

It may not matter yet because I’m getting different reading on the plugs even though carbs are set the same.


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[denward17]

I had to go to the center position to lean my '76 550 out some on the bottom end.  When I tore into carbs they were in the 4th position from top, or 2nd from tip.
The bike runs much better when at operating temp, but doesn't run quite as well when cold.  I now have to fiddle with the choke a little bit more, which I am ok with.  I guess I made it a little more cold natured.

Don't know if it matters, but I also installed new Honda needles/emulsion tubes.

At center position,  probably rich at WoT if you’re induction setup is stock. You should be second from top, fourth from tip. Moving to the middle enriches the carbs (raises the needle with throttle increase, allowing more fuel). Whomever had it second position from tip was either running pods, or was errant in their assembly.

According to various charts I have seen, I should be in 4th from top.

[brett_bike]

Oops


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[denward17]

^Where does that go?  It's been a while since my carbs were apart.

[brett_bike]

It’s the main jet holder inside the float bowl.


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[denward17]

It’s the main jet holder inside the float bowl.


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Thanks, now it registers, the butterfly as I like to call it.

[brett_bike]

That’s the one.

Used the clear tube methods again today and I guess I messed up before. The fuel level in my #1 carb was still too high so I d to remove the rack and reset/verify all the float settings…again.

When I removed the bowl I also noticed one of my bowl o-rings was pinched. Luckily it hasn’t leaked but I ordered new o-rings for all the bowls.


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[denward17]

I used a touch of wheel bearing grease in all 5 corners of the o ring for the float bowls to hold them in place.

[brett_bike]

To update what’s going g on with the bike…

By the suggestion of a fellow CB rider, I picked up some JB Weld putty and started plugging holes. My exhaust is rusted beyond repair, by the way.

On first ride it was leaps and bounds better.

It pulls smoothly all the way up the rpm range with zero stumbling anywhere. Since I only did a bench sync with the carbs off I need to go back and vacuum sync them and I’ll probably triple check the timing while I’m at it.

I was surprised but it seemed to fix the problem. I never thought holes in the exhaust would cause this sort of “acting up” of the bike but it seems it did.

I’m hoping to mount my GoPro and take it for a ride tomorrow. I’ll post a vid asap.

Thanks for all that helped try to alleviate this issue. This forum is the best!


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[brett_bike]

Well that was short lived. A new issue has popped up. At least I think it’s a new issue.

So the bike ran great for a couple of days. Then I’m back to the same sputtering issues until I removed the air filter, then it ran great. It’s an old filter so probably pretty clogged. I’ll be trying to track down a new Honda filter. Any recommendations on Uni vs Honda vs ? My previous CB500 had a single K&N that connected to the stock air plenum (no box) but I can’t seem to find anything like that style.

Anyhow…

So here I go again back into the entire tune up process to see what I may have missed.

Something strange happened while going through the tune up process. It’s kind of weird to describe but as I’m checking the timing with the automotive timing gun I get no flash on #3 while giving the throttle a twist to advance. I get a flash while advanced on all others. The coils are new from 4into1 and could be bad, I guess.

What’s weird is that I get a flash at idle but not while advanced in #3 only so it appears the advance unit is functioning correctly.

I’ll be testing the coils for resistance and making sure all is installed correctly.

Could the points be bad? Condensers? Would a Dyna electronic ignition system solve the issue?  I’ve used the Hondaman Tranzistorized ignition module in the past with great results.


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[Stev-o]

Any recommendations on Uni

 Condensers?

Do you have the OEM airbox? If yes, then the Uni air filter is a good option.

What brand of condensers do you have?  New aftermarket condensers seem to be trash, we've had many reports of them being bad.

[brett_bike]

Yes, stock air box.

Honda condensers. I have some stock ones sitting around from previous builds.


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[brett_bike]

Been a little bit since last update.

Kind of forgot where we left off but I purchased a few new parts.

Thinking that my rich (1-3) and lean (2-4) issue was due to condensers and/or points I ordered a Dyna electronic ignition. I’ve used Hondaman tranzistorized ignition in the past and wanted to try the dyna. I also picked up some used 4 into 2 exhaust. My original 4 into 4 were too rusted to salvage so I wanted to get something that didn’t look like Swiss cheese while trying to tune this thing.

I’m still getting the rich/lean issue mentioned above but it runs smoother without the air filter installed. I have no idea how old it is and it’s tough to tell how caked it is.

I’m thinking that since I have now replaced all the ignition parts I will dig back into the carbs and perform a test. I’m going to swap needles from the rich carbs to the lean carb. Install new plugs and do another plug chop. If the rich condition follows the needles then I’ll replace them. I guess there’s a chance they are not tapered correctly and letting too much fuel to pass.

Thought?

I gotta be honest. As frustrating as this is, I love the challenge.


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[denward17]

What kind of needles are in the bike now?  Do you have pics with the numbers stamped on them?

[grcamna2]

If this bike came to me for repair(after seeing what you've done to correct the ignition),I would remove the carbs. one last time and go through them 'with a fine tooth comb' in a manner of speaking.
Remove all the emulsion tubes and check all the needle jets:both the i.d. and how they all fit into the carb. bodies where each needle jet/nozzle is needing to seal against the carb,etc.
Take plenty of time with them and as denward17 has mentioned about the needles;the problem may be in the needles and needle jets,but either way.. IT'S A CARBURETOR PROBLEM.
Take your time   and inspect every little thing in them,no matter how minute;finally re-install them after your 100% sure you've checked everything in them.