Topic: Runs rough after top end rebuild.

[croquesaveur]

Hey All:

I bought a 78 CB550K a few months ago and thanks to the info on this board I got it running more or less perfectly.  The only problem was that it was leaking oil at the galleries and ruining my pants.

The bike is stock except for a 4:1 exhaust.

I got tired of the white-trash-absorbent-rope-around-the-cylinder-head "gasket" trick so I decided to do a top end rebuild from the base gasket up.  I did not replace the valve guides.

I then adjusted the cam chain tension, the valve clearances, and the timing --all are now correct.

Good news is the oil leak is gone and the bike idles better than before.  Bad news is that the engine is now kind of gutless.  It runs well at low RPM but sounds louder and pulls weakly above 3000-4000RPM.

A plug chop revealed that plug 1 and 3 were black and sooty while the other two looked normal.  Weird, I know.

Remembering that a couple plug caps had come off while I was rebuilding the top end, I bought new plug caps (5K) and new plugs (NGK D7EA) and double checked the valve clearances and timing (static method).  Everything is set correctly.

Still runs like crap.  I'm pretty sure I'm getting decent sparks --if I pull a plug cap off of a plug while revving then engine, I can hear the snap-snap-snap of the arc from the inside of the boot to the tip of the plug on all four cylinders.  Running the engine in the dark reveals no electric light show.  The battery is brand new and the electrical system on the rest of the bike seems to work fine.

While running, playing with the choke makes the engine run worse.  Running without the (stock) air filter also makes the engine run worse.

I doubt it's a carb issue as I had rebuilt them and they were working fine for several 1000kms before the rebuild and I didn't touch them during the rebuild.

Something that occurred to me tonight: What would happen if I didn't get the cam chain on the exact correct tooth on the sprocket?  Would this explain the problem?  I'm pretty sure I did it right, but I'm running out of easy stuff here.

Sorry for the long-ass post, I'm trying to anticipate all the initial questions you'll ask.

Any insight?  What should I check next?

You guys rock, and thanks for the help,

Chris.

[scondon]

   Long ass posts are good. The more info the better. Sounds like you've been pretty thorough and conscientious with your work. The only thing that raises a question for me is when you state that you timed the bike using the "static" method. Does this mean that you only checked the timing at the "F" mark?  Timing at "F" could be spot on but your advance timing could be way off which would give the symptoms you describe.

[TwoTired]

Have you done a compression check since the top end work?

Sure you didn't bend some valves puting the cam cover and rockers on the engine?

Cheers,

[yooperlou]

I rebuilt a kawa 650 some years ago and ran into somewhat of the same issues.  The correct tooth on the cam chain for that bike was crucial.  Being off one or two teeth causes all sorts of havoc.  If it is off enough your valves will not seat properly.  I know its a stretch but did you have the correct cylinders at TDC? as funny as that sounds we had issues with that from being brain dead.

[croquesaveur]

I haven't tested compression because I don't have the right adapter for my compression tester (I guess I'll have to buy another one).

I'm pretty sure I didn't bend a valve as I didn't disassemble the valves during my rebuild (I don't have a valve spring compresser).  How can I check?

I don't have a timing light either.  However, before the top-end rebuild I had set the timing using the static method and the bike had run fine.  Could it have changed enough that the static method wouldn't work anymore?  Yesterday I also took the advance mechanism off and inspected it.  Although lightly rusted I could move it easily with my fingers and I presume that it's in good shape.

One thing to note about my magneto.  While I was setting the timing yesterday (using a voltmeter with the ignition on), as I slowly turned the crank to the point where the points opened I could actually hear the arcing across the points.  I could have set the timing without the voltmeter.  If I run the bike without the points cover on, I can also observe lots of sparks across both sets of points.  Is this a sign that my condensers are shot or is this normal?

If I take off the cover to inspect the cam chain adjustment am I going to need to replace the gasket?  (Please say "no").

[crazypj]

Did you back off all the valve adjusters level with the bottom of rocker arm during disassemby or at least before reassembly? If not its possible  likely) that one of the adjusters caught on top of valve and could bend it. Where did you store fuel tank? the outlets on 550 point straight down so if you put it on bench one of them could be partly blocked. Did you pull front of cam chain tight when you checked cam timing (or turn it over several times) and verify position? At laest you dont have to pull motor to remove cam cover so its only a few hours to check most of this stuff (no need to remove carbs or exhaust either  )
PJ

[croquesaveur]

I did loosen the valve adjusters enough so that I could wiggle all of them, but I didn't back them out particularly far.

When I set up the cam chain on the sprocket it seemed like I had to choose the best tooth to line up as neither was dead-on.  I'm starting to think I might have my timing chain off by one notch.  Would that explain my symptoms?  Would being off by one notch pooch my engine?

Sounds like the first thing to check is my cam chain.  I'll look at it tonight after work.

[scondon]

One thing to note about my magneto. While I was setting the timing yesterday (using a voltmeter with the ignition on), as I slowly turned the crank to the point where the points opened I could actually hear the arcing across the points. I could have set the timing without the voltmeter. If I run the bike without the points cover on, I can also observe lots of sparks across both sets of points. Is this a sign that my condensers are shot or is this normal?

   You shouldn't have spark at the points and this could certainly rob power. Bad condensors and/or points. When I had this problem on my 750 I would have no power at speed, bike would rev up slowly.

  Any change in your point gap will change your "F" timing but not affect your advance timing. Spinning the timing plate will change the advance timing and "F" timing together. If your point gaps are too large/small and you spin the plate to set timing at "F" then your advance timing may get set out of adjustment.

 

[croquesaveur]

Right now my point gap is set on the big side of acceptable (0.016").  I'll try reducing it and resetting the timing to see if that helps.  Since this is easier than taking apart the top end first, I guess I'll try that first.

Are points/condensers still available through Honda?  Are they expensive?

[croquesaveur]

Sirius Consolidated is about twenty minutes away from me.  I'll pick up some points and condensers this afternoon and install them tonight.

Hopefully that will lick my problem in the butt.

Chris.

[TwoTired]

I'm pretty sure I didn't bend a valve as I didn't disassemble the valves during my rebuild (I don't have a valve spring compresser).  How can I check?

I did loosen the valve adjusters enough so that I could wiggle all of them, but I didn't back them out particularly far.

Page 32 of the Honda shop manual warns of intallation proceedures with the cam cover, where the tappet adjuster catches on the side of the valve stem tip while the cover is tigtened down.

That's why I asked for a compression check.

[scondon]

   I think .016" is acceptable gap for points. Get rid of the sparking problem first and see if that doesn't eliminate your problems. Points and condensors are cheap enough and should be changed anyway so if it doesn't fix your problems you are not out any time or money, and at best it may save you tearing into your engine again. Peace of mind is priceless when doing rebuilds IMHO, so if you have 'cause to worry that somethings amiss then by all means, pull the top and have a look. The other posters certainly have more 550 experience than I and have offered sound advice.

[croquesaveur]

TwoTired, I was aware of that issue (had seen it in the shop manual and the Clymer's manual) so I think I was pretty careful about getting everything lined up.  However, it's still possible I broke/bent a valve stem (it wouldn't be the first time I've screwed something up after being specifically warned about a peril).

I'm going to fix up my ignition tonight and see what's what.

If I did bone one or more of my valves, what do I do?  Is there any easy way to tell if they're messed up?  Everything looks okay through the adjusting holes if that counts for anything...

[TwoTired]

If I did bone one or more of my valves, what do I do?

Replace the bent valves?  Though I suppose it is possible, I never head of them being straightened.

Is there any easy way to tell if they're messed up?

Compression test.

If you put your finger in a small rigid tube, withdrawal is easy.  If you bend your finger, neither insertion or extraction is easy.

The valve stem is the same way.  If the tulip end is no longer in axial alignment, it also doesn't fit onto the seat correctly, causing leakage and loss of compression.  Further, if the stem is bent, valve movement can become sluggish, delaying it's closure against the return spring pressure.  Severe cases can hold the valve open long enough for the piston to hit it, bending it even more and preventing valve seal.

You can tune carbs, and ignition til doomsday.  But, if the cylinder has a compression issue, it's all just flail.

I hope you didn't bend the valves during assembly.  But, if so, you won't be the first to have done so.  FWIW, I always back the tappet adjusters WAY off during assembly.  One close call was enough to make me a believer.

Best of luck!

[croquesaveur]

Okay, I installed the new points and condensers last night and adjusted everything.  Although I could still hear an arc when the points opened while I was setting the timing, the points no longer sparked with the engine running.  The bike ran the same.

I took apart the top of the engine and examined the cam alignment.  It was off.  Not by one tooth, not by two teeth, but by almost 180 degrees.  Yeah, I'm a moron.  I must have forgotten to put cylinder 1 at TDC before setting the cam.  Oh the shame!  I'm amazed that the engine started easiliy and idled perfectly.

I fixed my bone-headed error and put everything back together and I have much, much more power than yesterday, but still not as much as before the engine rebuild.  This is, of course, anecdotal.  The engine is noisier, so it might just be that the exhaust header isn't tight enough and the additional noise is making me think that the engine isn't running the same.  It's popping and farting on deceleration a lot more than it used to so it might just be that.  How tight can those header bolts go?

Did I (i.e. could I have) mess(ed) up my engine by running it with the cam way out of sync with the rest of the engine?

I know, I know --do a compression test.  I'm working on it.  I just hate the idea buying a whole new compression gauge set just so I can get the silly adapter for my bike.

[crp_iii]

Autozone has a compression tester for about $30 that has all of the adapters that fit my bikes and cars.

[croquesaveur]

I'm in Canada, we don't have AutoZones here.  I checked a few places today, and the cheapest compression tester I could find that handles 12mm plugs is $50.  A bit steep for me since all I need is the silly adapter.  If I have to buy a whole new compression tester I will, but I won't have the spare scratch for that for another week or so.

Played around with the engine some more.  The engine seems to run fine until I open the throttle past maybe 1/4 to 1/3rd of the way open --RPMs seem to be irrelevant (although I can only rev the engine to about 4500RPM in second gear at this throttle setting).  If I open the throttle wide at lower RPMs I get the same symptom.  The symptom is very similar to what I was experiencing before --the engine gets louder and the sound changes.  If I had to describe the sound I'd say it goes from the normal VROOM to BRAAP.  The engine seems to have pretty good power, but not as much as it did before I did the rebuild.

I did a plug chop and found that plugs 2, 3, and 4 are all in good shape.  Plug 1 is black with soot.  I switched to another plug and the engine did the same thing.  Also the number 1 exhaust pipe feels cooler than the other three.  I double checked the timing (static method) and the tappet clearances on cylinder 1.  Both are perfect.  I also cut another half inch off the number 1 plug wire and put the boot on again.  Problem was unphased.

Finally, the left side oil gallery has begun leaking oil again.  So the whole point of my rebuild has been for nothing --I'm worse off than when I started!

1) Can anyone shed some light on my new symptoms (plug 1 black with carbon)?
2) I'm going to try to skip dumping another $120 on another gasket set and I'll take my chances that the existing gaskets will hold.  Can anyone tell me the size of the oil gallery O-rings?

[MotoRico]

Try this adapter.  I posted it months ago as I was in a similar situation.  I bought a compression tester that had a 14mm adapter but no 12mm adapter.  This is MUCH cheaper than any other adapter I found.

http://www.powerandperformancenews.com/store/merchant.mvc?Screen=PROD&Store_Code=PH&Product_Code=POW301052&Category_Code=

If the link doesn't work it is a PowerHouse 12MM adapter part #POW301052.

I know other people will need this part at some time.  Perhaps if it is still available it could be added to the FAQ or something.

[croquesaveur]

MotoRico, you made me realize that there are places that actually sell these things.  After a bit of searching I found that my local NAPA Auto Parts store carries them.  They're a bit more expensive than the store you mentioned ($13 vs. $6) but I don't have to pay shipping and I get the tool today.

If the weather holds out, I'll do a compression test tonight and post the results.  Obviously I'm hoping that compression is okay, but if it is I can only think of two things that could be causing poor firing on only cylinder one: a) a bad plug wire, or b) carb 1 needs cleaning.

[maksuttt]

Try Canadian tire for compression tester. I bought mine there.

[croquesaveur]

I brought home the 12mm adapter and tested out my compression.

I got the following:

Cold Engine (psi, Cylinders 1 - 4): 120, 105, 110, 120
Hot Engine (psi, Cylinders 1 - 4): 125, 115, 122, 120
Hot Engine with oil (five second spray of WD-40) (psi, Cylinders 1 - 4): 125, 115, 120, 120

Surpringly, my "bad" cylinder has the best compression.  I'm interpreting these numbers as vindicating my valves and pistons as they seem high enough to me (considering there's about two feet of rubber hose between the cylinder and the gauge, I'm guessing that the "actual" compression is quite a bit higher).

Continuing with the troubleshooting, I swapped the fouled plug in cylinder 1 with a good one in cylinder 4 and took it for a ride.  The old bad plug (the one that was moved from 1 to 4) was cleaned up somewhat, and the old good plug (moved from 4 to 1) was fouled.  The problem didn't follow the plug, so I guess I can conclude the problem is not the plug.

Then I swapped the 1 and 4 plug wires (they just reached) and took it for a ride.  The problem did not follow the wire, so I guess I can conclude the problem is not the spark plug wire.

I'm running out of things to test!  I guess the only thing left is carb #1.  I had rebuilt carb #1 with a Keyster kit about one month and 1000km ago, so I figure it's the least likely to be messed up, but after thinking a bit, I suppose, when my camshaft was off by nearly 180 degrees, it's possible that cylinder was doing something wacky like sucking in from the exhaust and blowing back towards the carb so, for all I know, carb #1 could be in really rough shape.  I hope all it needs is a cleaning.

I can't believe I botched the cam timing so badly!

[TwoTired]

Did you rebuild all the carbs with keyster kits?  Or, just Number 1.

There have been other reports that the parts in the Keyster kits are different from stock components.  The slide needle in particular.

If the carbs have different internal parts across the bank, that's an easy explanation for your fouling issues.

Glad to hear your compression is good.  But, I think WD-40 is too thin an oil for a "wet" test.  You need 20w or thicker to make an effective ring seal.

Cheers,

[croquesaveur]

Actually, I only rebuilt carb #1 because it was leaking.  I replaced the jets and gaskets, but I did not replace the needle because a) I couldn't be bothered to unrack the carbs, and b) I had heard people grumbling about Keyster needles.  When I replaced the jet I confirmed that the value I was replacing matched the other carbs which also match stock (can't remember the size off the top of my head).

Weather permitting, I'll have something (hopefully good) to report tomorrow.

[croquesaveur]

I finally got it running properly!

I took out the carbs, pulled the bowl off of carb 1 and sitting at the bottom of it, was the jet.  The jet must have worked its way loose.  I screwed it back into the holder (fairly tightly) and put everything back together (is there any machine that is more of a pain in the ass to get at the carbs than CBs?) 

With no main jet, what does that work out to a #250?  No wonder that cylinder was running rich!

For my own edification, was I supposed to do something to keep the jet from working its way out or was that just a freak occurrence?

Thanks for your help everyone.

[Tim.]

I was about to chime in with a source for a compression tester in Canada...  Canadian Tire.

http://www.canadiantire.ca/assortments/product_detail.jsp?FOLDER%3C%3Efolder_id=1408474396669498&ASSORTMENT%3C%3East_id=1408474396670271&bmUID=1153525858700&PRODUCT%3C%3Eprd_id=845524443271224&assortment=primary&fromSearch=true

$30 and has the 12mm adaptor.