Topic: CB550 is Dying...

[Zoom]

Hello everyone,

  I am new here, but rest assured, I did use the search feature first and I couldn't find anything quite like the problem I'm experiencing. Ok, I'll start from the beginning.

- Got a 1975 CB550 for free
- Has no air filter, open headers
- Poured gas in it, carbs spilled gas all over the floor
- Rebuilt carbs, installed new fuel lines
- Adjusted air mixture screws to 1 turn out as per oldmanhonda.com
- Still running stock jetting
- Bike ran fairly well
- Decided to take it drag racing
- Bike didn't want full throttle, would die down if I twisted the throttle ALL the way but did ok at 95% throttle
- Bike wouldn't rev past 6000 RPM
- Bike didn't do bad (best run was 15.75 seconds)
- Then, at approximately 50 mph (and about 5500 RPM), it suddenly lost power
- No horrible sounds or anything, it just lost power
- Sadness
- Rode it back to the pits, it idles fine and revs up ok until its under load
- Reduced acceleration under load
- One cylinder is running colder than the others (outermost cylinder on throttle grip side)
- When checking the plugs, a wire ripped, thought that was the problem, fixed it
- Bike still doesn't accelerate properly
- Removing the spark plug from the colder cylinder makes a difference in the engine speed, but not much
- Can't find a compression tester with the right size thread
- A little bit of oil leaks from around the shifter, but that was already happening (I'd like to fix this too)

Sorry about the point form, I just wanted to make things a bit easier to read. I don't know about you guys, but long paragraphs make it difficult for me to analyze a problem.

I could really use any help or advice anyone has to offer. If you don't want to post here then please e-mail me at jdcoates@gmail.com

[Klark Kent]

from the oil & fuel FAQ:

There is an oil leak coming from my shifter seal – how do I change it?
1. Undo the bolt on the back of gearchange (foot) lever. 2. Make a mental note of the usual position of the gearchange lever, and then pull it straight off of its splined gearchange shaft. 3. Undo the bolts on the left-side engine case that covers the front sprocket for the chain, and pull the cover straight off. There is no gasket or oil behind this cover. Just the chain sprocket. 4. Using needlenose pliers or a similar tool, try to grab the old O-ring shaped Oil Seal and pull it out from it's insert on the side of crankcase body. Do not scrape or damage the seal insert area. Slide the Oil Seal outwards along the gearchange shaft to remove it. Even if this Oil Seal looks good, discard it. This Oil Seal MUST fit snugly, otherwise oil will continue to leak out from behind the gearchange shaft. Oil is intended to squirt through a small channel from inside the crankcase into a hollow ridge on the backside of the Oil Seal in order to keep the gearchange shaft constantly lubricated. Remember, the old Oil Seal may have hardened or changed shape slightly over time. 5. Install a new Honda O-ring Oil Seal (approx $5.00). It might help to find a hollow rod (like the handle of a hydraulic jack) slightly longer than the gearchange shaft in order to lightly tap the new Oil Seal into its insert. The Oil Seal should fit almost flush inside crankcase insert. 6. Re-install the engine case (cover). 7. Prior to re-installing the gearchange lever, slide a rubber spacer (similar to a garden hose washer) onto the gearchange shaft right up against the engine case. THEN install the gearchange lever. This will limit lateral (sideways) movement of the gearchange shaft, thus reducing the chance of the new oil seal from getting caught up on the shaft and gradually pulled out of its insert. Make sure that the gearchange lever can still move freely up and down - just not sideways.

Also a good post by a member called csendker wherein he diagnoses the shifter seal problem.  search for that one.

the carb adjust chart that Lloyd would post if he saw your question is below.  (Lloyd, if i save you some time now, can i waste some of it later with some more questions? )  The chart will tell you what to clean again or adjust within your carbs (and what to leave alone) based on where your problems are along the throttle scale.

long lists make it hard for me to remember what was on them- you got the valves adjusted and the timing set, carbs synched   search for basic tune up. 

Good luck
-KK

[TwoTired]

- Got a 1975 CB550 for free

Cool.  However, all the free bikes I ever got cost money to make run right.  Be prepared.

- Has no air filter, open headers

If you care that it will wear out much earlier, put on air filters.

- Adjusted air mixture screws to 1 turn out as per oldmanhonda.com

Stock book settings don't apply to bikes with modified intake and exhaust components

- Still running stock jetting

Mistake.  (With those mods.)

- Bike ran fairly well

Okay...Compared to.....?

- Decided to take it drag racing
- Bike didn't want full throttle, would die down if I twisted the throttle ALL the way but did ok at 95% throttle
- Bike wouldn't rev past 6000 RPM

Bigger main jets needed for that configuration probably.  Going way lean at WOT, I expect.

- Bike didn't do bad (best run was 15.75 seconds)

All those "performance mods" and it's a full second slower than a stock configured bike.
Thanks, for sharing.  Really.  Most of the posters just mod their bike and brag about how much faster it "feels" or "sounds".  Kudos for posting actual track time.

- Then, at approximately 50 mph (and about 5500 RPM), it suddenly lost power
- Reduced acceleration under load
- One cylinder is running colder than the others (outermost cylinder on throttle grip side)
- Removing the spark plug from the colder cylinder makes a difference in the engine speed, but not much
- Can't find a compression tester with the right size thread

Oops,  It's broken.
Wild guess is that the bike was running really lean and flogging it burned a valve (or something), possibly had detonation and damaged the cylinder mechanicals.  Take out the spark plugs and compare them to:
http://www.dansmc.com/Spark_Plugs/Spark_Plugs_catalog.html

Probably too late now, but learn to do plug chops on modified bikes that you care about so they last a little longer.

Oh well.  It was free.  Just throw it away or sell off the remaining parts and find another free bike.
Or, maybe you can find another free engine?

- A little bit of oil leaks from around the shifter, but that was already happening (I'd like to fix this too)

Who cares? it was free, just throw it away and find another one.  However, if you ever get compression back in the cylinder, look for threads about the shift shaft seal replacement.

I could be wrong, but I'm guessing you're not going to spend 200-500 bucks getting your free bike running well again.

Best of Luck!

[Zoom]

Klark,


Thanks for the info. I'll definitely put that to good use if I can get the other problems fixed.

TwoTired,

  That was a pretty harsh post.
  I should probably explain that I know it's running way too lean. I would've run exhaust and an intake if the free bike had came with an exhaust and an intake.
  I should also explain that I don't have a lot of money. Yes, I am willing to spend a couple of hundred dollars to get this bike running again, but I first wanted to make sure everything was ok on it (shifted through all gears, would handle all RPMs, etc) before I started buying different stuff for it. I figured if it blew up, I'd just part it out. I'm still considering that.
  Part of the reason why my quarter mile time sucked is because I had no practice on that particular bike beforehand, I'm more used to sportbikes. The other reason is that I'm just not that good at drag racing. I've ridden motorcycles for thirteen years, but I've only drag raced twice.

I was just wondering if anyone had any insight into the particular problem. I'm going to go rip the head off the bike now, so I may have parts for sale soon.

[my78k]

Not that TT needs me to back him up or anything but I didn't find that post too harsh...

As you can see from his post count he is a very active member and what you can't see is that he is likely one of the most respected in terms of his knowledge and willingness to share it.

I'm guessing what he was getting at was the fact that it was freebie so the fact that it died probably wasn't that big a deal...as we all know with these older bikes they are worth far more parted out than they are intact. He probably assumed since it was a freebie with the potential to part out that you may be hesitant to put a ton of time and money into a rebuild...

As for me, I'm a little surprised that you would jump on a freebie bike that wasn't complete and tear off down a drag strip! Not a shot at you in anyway so please don't take it that way...I just personally have been working on mine forever now and am only starting to get it to the point where I trust it around the neighbourhood let alone at WOT on a drag strip...you must have a serious set of stones! Ofcourse a few years and a couple of kids ago I probably would have done the same thing 

Dennis

[dusterdude]

zoom,thats tt,you hang around here long enough you`ll learn twotired knows his #$%* and he tells it to the point.overall,ive never seen him give anyone any real grief.listen to what he has to say and you`ll be better for it.

[Klark Kent]

I just rattled off some basic info.  TT diagnosed your problem based on the symptoms you gave us.  the way i read it was, bad news: you have probably lost compression in one cylinder. good news: you can fix it and still have a great bike for less than $500.  If you do decide to part out I need a right side cover (yer bike's not green is it?!?)  and maybe some other stuff.  Where are you located??
-KK

[Zoom]

I guess I just interpreted TwoTired's post wrong. I apologize.

I already sold the side covers on eBay, sorry. They were the green though.

I'm probably going to part this bike out. I just looked at the spark plugs and each one of them is WAY off. Only one of them was white enough to indicate a lean mixture.

I'm located in Windsor, Ontario (20 minutes from Detroit, Michigan).

I have original bars, grips, throttle and brake assemblies, rebuilt carbs, and just about everything else except for some bodywork. If there's anyone located near me that wants to pick up a bunch of parts, I'll give you a good deal on them.

Otherwise, keep an eye out on eBay.

[cadler]

I would replace your points also, because the conderser is probably beat and your points will burn up fast

[dusterdude]

dude,dont throw in the towel now.