Topic: Issue with cylinders 1 and 2 on '76 CB550

[RisforRobots]

Hi All,

First time posting and novice to the joys of motorcycle maintenance. I have a 1976 CB550 I bought about 4 years ago. I am currently having power issues. All four cylinders are firing, it kicks over in one to two kicks, sounds right and idles perfectly, but when I put it in gear and pull out onto the road it just doesn't have the get up and go it has had. When I touch the exhaust pipes, 3 and 4 are HOT, while 1 and 2 are warm enough to indicate combustion/running but they are no where near the temperature of 3 and 4. Also noticed a good amount of oil coming out from the fins near the head gasket on the #1 cyl.

Not sure how to begin to diagnose this, any help would be appreciated.

As for the bike, here is a listing of current setup and work that's been done:

1976 CB550
Antigravity battery
Rick's Motorsports Regulator Rectifier
K&N Pods with proper jetting (been running it this way for 4 years no problems)
Dyna Tech 5ohm Coils
4-into-1 exhaust (PO installed)
New points and condensers (last month)
Timing and valve job done at the time I replaced the points
Hondaman ignition installed and running well
Upgraded all lighting to LEDs

Doubtful that this has anything to do with the problem but I have also gone through and cleaned all the electrical bullet connectors in the wiring harness

I am located in Brooklyn NY working with limited courtyard space, any help or suggestions would be SO appreciated.

Thank you!

[RisforRobots]

Forgot to include that I pulled and cleaned the carbs at the same time I replaced the points and condensers.

Thanks!

[ekpent]

 Doesn't really sound like coil or points as the fire 1/4 and 2/3 and your problem is a 1/2 so maybe fuel related issue. Are you running fuel filters and are you 100% certain the carbs are set-up correctly.

[Gene]

Check to make sure that your plug wires are correct.  By that I mean that 1 & 4 are on one coil and 2 & 3 on the other - Left and Right respectively.  Sounds to me like you may have a points/condensors problem, but the wires are run funky. Typically you'll have an issue w/ 1 & 4 or 2 & 3, not 1 & 2.

Sounds like you just did, or had, some work.  Just a theory. Plus, what did you replace the points & condensers with?  Daichi? If so, get some decent parts and replace.

[RisforRobots]

Check to make sure that your plug wires are correct.  By that I mean that 1 & 4 are on one coil and 2 & 3 on the other - Left and Right respectively.  Sounds to me like you may have a points/condensors problem, but the wires are run funky. Typically you'll have an issue w/ 1 & 4 or 2 & 3, not 1 & 2.

Sounds like you just did, or had, some work.  Just a theory. Plus, what did you replace the points & condensers with?  Daichi? If so, get some decent parts and replace.

Thanks for the comment ... Wiring is correct, from the points to the coils and the right wires from the right coils to the right cylinders.

[RisforRobots]

Doesn't really sound like coil or points as the fire 1/4 and 2/3 and your problem is a 1/2 so maybe fuel related issue. Are you running fuel filters and are you 100% certain the carbs are set-up correctly.

Yeah, agree with you about the coils and points not being the issue.

Carbs are set-up right, and sync'd. 

I am running fuel filters, will check to see if they are clogged for some reason. Like the idea that maybe its a fuel issue, seems like an easier fix than my other fears.

Thank you, will update as I find out.

[Deltarider]

Let's assume you don't have a leaking cylinder head gasket.

I am running fuel filters

Socalled inline fuel filters are a known cause of problems on our bikes, not necessarily but it can. Most irritating is that sometimes fuel flow is good and even after weeks of no-prob riding they can start to hinder fuel delivery. Besides: if the fuelcock filter is still OK (the CB550K2 had the good nylon one protruding into the tank), extra fuel filters offer you nothing. Fuelline to the T-joint of carbs 1+2 on your model should have a length of 17 cm with an ideal ⌀ of 5,5 mm. The line to 3+4 should measure 28cm. If you happen to have the old model fuelcock (with the bowl) fuel lines lengths are 18 and 30 cm respectively. With the correct dimensions there's no chance of kinking.

[BomberMann650]

If not fuel, check compression and valves

[calj737]

Easy enough to ascertain whats going on in 1&2 by pulling your plugs and posting pictures of them. Do the same for 3&4 for a comparison.

When you cleaned the carbs, did you properly reset the float heights on all four carbs? If you discover 1&2 are more lean than 3&4, I'd immediately suspect fuel level in those two carbs is lower than the other pair. Fuel filters can be a problem, but would normally effect all four carbs equally.

Clear Tube method for checking fuel level-

PS - If you are running Hondaman's ignition, you can't be running points and condensers too. So, which configuration is true?

[Deltarider]

Fuel filters can be a problem, but would normally effect all four carbs equally.

Correct unless socalled inline fuelfilters are used. The CB550K2 has a dual output petcock and fuel is delivered by two separate fuellines. If there are inline fuel filters in both fuellines it is possible one can give problems and the other will deliver freely. I have experienced this more than once and therefore abandoned them.

If you are running Hondaman's ignition, you can't be running points and condensers too. So, which configuration is true?

Hondaman's ignition module will still need points to switch control current.

[calj737]

But Hondaman's ignition module still needs points to switch control current.

I am aware of the requirements with his ignition. The query was posed to the OP who posted conflicting information; that he was running the HM ignition, but that he also just replaced the points and condensers. So which is true; HM or P/C?

[Deltarider]

I am aware of the requirements with his ignition. The query was posed to the OP who posted conflicting information; that he was running the HM ignition, but that he also just replaced the points and condensers. So which is true; HM or P/C?

With all respect, I don't see the conflict.

[calj737]

I am aware of the requirements with his ignition. The query was posed to the OP who posted conflicting information; that he was running the HM ignition, but that he also just replaced the points and condensers. So which is true; HM or P/C?

With all respect, I don't see the conflict.

I can explain it to you, but I can't understand it for you.

[lrutt]

check your plug caps. I had the same problem on my bike just this last week. Tested everything, new plugs, same problem. Tested the caps and 1 was at 12k ohms and one at 8k ohms. That would do it. Ordered new caps from DK.

[Deltarider]

I can explain it to you, but I can't understand it for you.

Look, the man has listed what he's done so far: new points, new condensors, Hondaman's ignition and he has answered that the wiring is done OK. There's no conflicting info. So what's there to understand? But wait, maybe you'd better not explain. Anyway, the issue is with cyl 1+2.

[RisforRobots]

Let's assume you don't have a leaking cylinder head gasket.

I am running fuel filters

Socalled inline fuel filters are a known cause of problems on our bikes, not necessarily but it can. Most irritating is that sometimes fuel flow is good and even after weeks of no-prob riding they can start to hinder fuel delivery. Besides: if the fuelcock filter is still OK (the CB550K2 had the good nylon one protruding into the tank), extra fuel filters offer you nothing. Fuelline to the T-joint of carbs 1+2 on your model should have a length of 17 cm with an ideal ⌀ of 5,5 mm. The line to 3+4 should measure 28cm. If you happen to have the old model fuelcock (with the bowl) fuel lines lengths are 18 and 30 cm respectively. With the correct dimensions there's no chance of kinking.

I had no idea! Thanks, and thanks for the line lengths, will double check them.

[RisforRobots]

Easy enough to ascertain whats going on in 1&2 by pulling your plugs and posting pictures of them. Do the same for 3&4 for a comparison.

When you cleaned the carbs, did you properly reset the float heights on all four carbs? If you discover 1&2 are more lean than 3&4, I'd immediately suspect fuel level in those two carbs is lower than the other pair. Fuel filters can be a problem, but would normally effect all four carbs equally.

Clear Tube method for checking fuel level-

PS - If you are running Hondaman's ignition, you can't be running points and condensers too. So, which configuration is true?

Thanks for the clear tube fuel level diagram. Never seen that before. Floats are correct, assuming I leveled them correctly. Will double check via the fuel level test and report back.

As for the points vs Hondaman ... as some of the subsequent posts stated, you still need the points to signal the Hondaman ignition. I replaced the points and the condensers, and ran the bike that way for a bit then installed the Hondaman ignition.

Thanks again

[RisforRobots]

Fuel filters can be a problem, but would normally effect all four carbs equally.

Correct unless socalled inline fuelfilters are used. The CB550K2 has a dual output petcock and fuel is delivered by two separate fuellines. If there are inline fuel filters in both fuellines it is possible one can give problems and the other will deliver freely. I have experienced this more than once and therefore abandoned them.

If you are running Hondaman's ignition, you can't be running points and condensers too. So, which configuration is true?

Hondaman's ignition module still

needs

points to switch control current.

Yup! Thanks!

[RisforRobots]

check your plug caps. I had the same problem on my bike just this last week. Tested everything, new plugs, same problem. Tested the caps and 1 was at 12k ohms and one at 8k ohms. That would do it. Ordered new caps from DK.

Oh interesting! Will check the fuel line issues first and then test this. Thanks for the tip!

[RisforRobots]

Finally back from work travels. Ended up being a fuel line issue. The installed fuel filters were gummed up with varnish and were causing a kink. Replaced fuel line and switched to smaller filters, has been running great for the past 4 days. Thanks all for the help!