Topic: 1978 Cb 550 Overheating and weird timing issue... with pictures!

[Nestcraft]

I have a 1978 CB 550 that I have been working on over the last few months, basically got it for free and am converting it to a cafe. (pictures attached)  I have put almost 1,000 miles on it over the last 1.5 months and it has ran pretty good, the last few weeks I have been dialing in the carb jetting.  She ran a bit warm but not so much that it ever overheated.  I rode many times for 2 -3 hours with no issues.

About a week ago I changed the oil, I was running Honda Brand 10w40 and I switched to Bel Ray EXL Mineral 20w50 and added Rislone Zinc additive as recommended by several on this forum.  I also replaced all of leaking O rings in the oil pump, replaced the shifter shaft seal, counter sprocket seal, brake lever seal and changed the clutch plates.

I also realized I had a massive vacuum leak at the intake manifold so I replaced those O rings, while the carbs were off I decided to  "fine tooth comb" everthing internal and found out that I had overlooked some build up inside the idle jets.

Seems like this should all be good right?  Well, it has been downhill ever since!

Right now my set up is this: (bike has about 18,000 miles on it)

#40 Idle Jets (OEM ,although one of these four seem to have a slightly smaller hole than the others....)
#105 Mains
Uni "short" foam pod filters- oiled
Mac 4 into 1 Exhaust
NGK D8EA plugs
Stock points and condensers
Stock coils

My plugs are telling me that things are running rich, I have not done a formal plug chop yet and won't be able to until I get the overheating figured out.  What is driving me crazy is that I fixed some major air leaks and cleaned a bunch of gunk out of the idle jets so this thing should be running much richer right?!!!   No, now it is overheating... within 10 minutes of riding.

I have set the valves and rechecked the valves.  I also ran it a bit with the tappet covers off to verify that oil is getting moved through the top end.  It is!

I have synched the carbs everytime after any jetting changes or fiddling.  It idles great when cold, and runs great until it gets too hot, then it detunes itself. 

I checked the timing the other night and it was advanced a good deal... hmmm.  I got it set dead on, checked the points gap, dead on.  I ran the bike for a bit... rechecked the timing, 1/4 was off again.... hmmm.  It must have been something I did, do I reset it again.  Ran the bike for a bike, checked the timing and it seemed OK.  Today I took it out for a spin and it got hot enough to detune itself again after about 10 minutes of not very aggressive riding.  I put it on the lift and checked the timing.... it was off  again, slightly advanced.  So I set it.... dead on.  Ran the bike for a bit and the timing was off again.  I pulled the plate off and checked that the springs and everything were in good shape behind the plate and they were.

I don't have a timing light so I have been setting the timing with the static method.

WHAT THE HELL IS GOING ON!!!!!!!!!! 

Can the timing make a bike run that hot?
If the timing is advanced will the bike run strong?
Can my jetting be that lean even after the air leaks have been fixed and if my plugs are black and sooty?


I am at my end of what to do next, someone please lend me a few next steps.

I love reading this forum but now I guess I AM THAT guy with the crazy, possessed bike.

Thanks in advance.  If you need other info please just let me know!
Mike

[Trad]

How do you know the bike is over heating? There are so many things that could be going on, I'm just curious how you've come to the over heating conclusion? laser temp gun? Unless you are seeing upwards of 550F at the headers or 250F in the oil I highly doubt its overheating.

You need to start ruling things out one by one. If your plugs are dry and sooty at least you know you are getting fuel and have some what of a spark.

Start with the easy things first. Compression checks out?

I would also switch to D7EA plugs right off the hop.

Are you getting proper resistance between the 1-4 and 2-3 coils?

[Nestcraft]

Thanks Trad,
First things first, I don't have a temp gun, nor a compression tester.   Both are on my list to get.

Right now the bike is getting hot enough that I can't hold my hand on any part of the cases for more than half a second.  It is much hotter than it ever got on any of the previous 1,000 miles of riding I have done over the last month and a half.  I have the headers wrapped so that temp will not be easy to get.  As pictures indicate.

The bike has ran great as for the last 1,000 miles and it still runs great out of gate cold, until it gets too hot.  Then it just sounds detuned and has either way too low of an idle or way to high of an idle.   

When the bike is cold it idles great, I don't even need to choke it to start, pops right off.

I found a post from Hondaman saying that if your orings are shot at the intake it will actually make the bike run rich and blacken the plugs.... now that the orings are fresh perhaps I am just getting a true indicator of the main jets being too small?

I have new carb boots on the way and new stock #40 slow jets (just to be sure the PO didn't drill them), as well as larger mains.  I am hoping that solves the issues.  The timing is a bit goofy but I need to check it dynamically too.

[scottly]

If your plugs are sooty, the carbs are at fault. Once the plugs have been covered with soot, symptoms may continue even after the original fault has been corrected. Either burn the soot off the plugs with a propane torch, or fit new plugs before proceeding. If clean plugs get sooty right away, you still have a carburetor problem.

[Nestcraft]

Thanks Scottly,
I am going to pick up a couple of fresh sets of D7EA's tomorrow but I will make sure I have a torch handy!

[DaveBarbier]

Nice bike!

I was under the impression the pilot jets were unobtainable. And I looked for months. You have PD46C's? Are you certain the one's coming in are Keihin? Either way, good that you're changing them out. Aftermarket jets are better than Keihin jets which have been drilled differently/poorly by a PO. What's your needle setting? What's your IMS set at?

You say that it idles great when cold and starts without choke. I don't think if a bike starts cold without choke that means it's running better than one that needs choke. You should always need to use a bit of choke to start a cold bike. That means your pilot circuit is rich, which is contributing to making your plugs black. Remember that a bike can be rich at idle and lean at 1/2 or 3/4 throttle making the bike run hotter. I think this is the exact time you'd want to do a plug chop.

When you feel it's overheated does it lose power or have clutch/shifting problems?

When you cleaned your carbs are you certain they're spotless inside? You removed the emulsion tubes and cleaned all the tiny holes?

Lastly, get a timing light. They can be had cheap on eBay and will tell you exactly what your timing is at advance.

[Nestcraft]

Thanks for the reply Dave,  I really enjoyed your build thread a while back while I was getting started on my 550!

Yes, the carbs are PD46's.  I ordered the new slow jets from 4into1.com, Jets R Us have them too.

I too believe the pilot circuit is too rich...  before I got the slow jets "ungunked" last week I always needed a bit of choke to get the bike started and warmed up. 

The main change when the bike gets hot is that it won't idle, stumbles badly and sounds detuned, the idle seems to be either 800 or 2000 (just an estimation).

I haven't noticed any shifting problems with the "overheating".

I have had the carbs off at least a dozen times, cleaned, switched jets and installed new emulsion tubes on the mains.

I am really feeling like the pilots are too rich and the mains are way too lean, making the bike run hot and then not letting it idle smoothly since it is too rich.  Since I can get a wire through 3 of the "stock" #40 slow jets and not through the 4th one, even after cleaning and boiling, it makes me think that they are not so stock.

The timing issue, however, is weird, someone else recommended that I take the stator cover off and make sure that the key isn't sheared and slipping.  I will need to pick a new gasket before I can do that.  I am picking up a timing light today to check the advance.

[DaveBarbier]

Thanks for the reply Dave,  I really enjoyed your build thread a while back while I was getting started on my 550!

Thanks, yeah it's always fun to document things. I go back and read when I'm bored, ha.

Yes, the carbs are PD46's.  I ordered the new slow jets from 4into1.com, Jets R Us have them too.

Post here when you get them. I'll bet money that they're Keyster.

The timing issue, however, is weird, someone else recommended that I take the stator cover off and make sure that the key isn't sheared and slipping.  I will need to pick a new gasket before I can do that.  I am picking up a timing light today to check the advance.

There's no "key" under the stator cover on the crank. And besides, you can reuse that gasket if you want, there's no oil behind it. It's just to keep things inside clean. But actually, as I type this I remember how impossible it is to get off in one piece. You can make one out of a thick paper if you don't want to buy an actual gasket.

There is a hole in the crank behind the points cover that the advancer mechanism keys into for proper orientation. That could be what they're referring to...?

[Nestcraft]

Thanks Dave, that saves me the time in looking into that!  Yes, they are Keyster slow jets...

calj737, Someone on another forum thought that if the key was sheared on the stator side that the flywheel would slip on the crank and the timing would appear to change even though it isn't.  I understand that the ignition settings are changed under the points cover.

[Nestcraft]

I don't think he was making the case that the sheared pin would account for the rich/lean condition but more for the "moving around" of the timing.

I would think that the bike would be acting all kinds of crazy if a sheared pin was the case... but I do appreciate the ideas even if they are far out.   

However, now I am curious if anyone knows for sure what would happen if the pin was sheared off?

[RevDoc]

That is jumping off a building to cross the street kind of logic... I'm sorry, but whomever gave that advice is a moron.

Your symptoms are pretty clearly carb related. Maybe your ignition plate/condensers/points are also misbehaving, but to presume a sheared key on the flywheel to account for a variable rich/lean condition is diagnosing a brain tumor for a twisted ankle.

Just my opinion, but then again, I don't have a brain tumor. OR a medical degree.
[/quote

+1 To Cal's response. Whoever gave that advice knows just enough to be dangerous!

[Nestcraft]

Thanks Revdoc, I will let that idea escape my brain.

[DaveBarbier]

Thanks Dave, that saves me the time in looking into that!  Yes, they are Keyster slow jets...

calj737, Someone on another forum thought that if the key was sheared on the stator side that the flywheel would slip on the crank and the timing would appear to change even though it isn't.  I understand that the ignition settings are changed under the points cover.

Oh, when you said "stock slow jets" I thought you meant OEM, which aren't available. My mistake. You must have meant stock size, but stock size is 42 for our bikes not 40 for your information.

But what's all this talk about a pin on the stator side? There IS no pin holding anything together on the stator side...and to be honest, I don't even know what the flywheel would be in these bikes. The rotor? Yeah, as others have mentioned...forget that.

[Scott S]

 I think what they are talking about is the pin that locates the advance mechanism onto the end of the crank. If it's sheared, the timing could be changing. It's under the points cover....no need for a new gasket to check that.

 Or just put a Pamco on it!

[Nestcraft]

I will be upgrading to an electronic ignition soon,  I just need to sort the other things first.   I put an electronic ignition unit from Charlies Place on my CB 350 Twin and it has run perfectly ever since.

Yes Dave,  I meant stock size. .. I have read many places that the stock slow jet is #40 on the 1978, the Kehin that are in it now are labeled #40, at least with new 40's I will have a known baseline.  I have #45s too but they were way too much.

Thanks for all the input so far.   This forum is such a great resource.

[DaveBarbier]

Yes Dave,  I meant stock size. .. I have read many places that the stock slow jet is #40 on the 1978, the Kehin that are in it now are labeled #40, at least with new 40's I will have a known baseline.  I have #45s too but they were way too much.

This is from the manual. I think actually from an addendum that a member TwoTired posted in one of my threads a little while ago.

[Nestcraft]

Thanks Dave,  I will have to start with the 40's since they already shipped.

[Trad]

If your plugs are sooty, the carbs are at fault. Once the plugs have been covered with soot, symptoms may continue even after the original fault has been corrected. Either burn the soot off the plugs with a propane torch, or fit new plugs before proceeding. If clean plugs get sooty right away, you still have a carburetor problem.

Sooty plugs do not always mean the carbs are at fault though. They are a sign of an incomplete burn and that can very well be ignition related.

[Nestcraft]

I picked up a timing light and gave the ignition a quick check today over lunch, the advance seems to be functioning properly... 1/4 were dead on but 2/3 were a bit advanced and need a little adjustment.  I will get that sorted out this evening.

[Nestcraft]

Hey Guys,
I just wanted to give an update...

This evening I installed new intake boots, the new #40 Keyster pilot jets, #112 main jets and I ran new threads in my carb clamps and got new bolts to secure everything.

It runs much, much, much better.  It also is running waaaaayyyyyy cooler (granted it is about 40 degrees cooler here than it was a week ago).  I can't say it is a lot more responsive but it is much smoother and comes down to a nice, even idle.

I worked with the timing and got is sorted out, going to pick up a Dyna in a week or two so that should smooth things out even further.

When I returned home from about a 45 minute ride, around the city and about 12 miles of interstate I pulled into the shop got it up on the lift and noticed I was getting some smoke both at idle and a bit at revs, I wasn't getting any smoking before the ride.  It is not a lot and to me the bike doesn't seem rich, the plugs were a bit sooty (light dry soot) but better than they ever have been. 

I also have a set of #118 mains, I may try those and see if the smoking gets worse and see if the responsiveness of bike picks up or falls off.  If it gets worse I guess could order a set of #110s...  I had #105s  installed previously, when it was overheating.

Next week I plan to do a proper plug chop, but is there something else that may cause some very minor puffs of smoke?  I need to replace the cam cover "o ring" gasket as it is leaking a bit, should I do the valve seals at the same time?  Can leaky valve seals create some smoke?

Thanks again for everyone's input on this!

[harisuluv]

Interesting read.  First thing that struck me was the constant use of the word "seem" or "seems like."  This is not troubleshooting or how to troubleshoot.  Don't think this way, instead of "seems rich" try "smells strongly of gas, or has fouled plugs." 

Next, you seem extremely fixated on this "overheating" issue.  Did the bike ever overheat and lock the cylinders?  Or are you simply using this term liberally to mean "got hot."  Surprised no one has mentioned this, but these are air cooled engines.  And when you mentioned you couldn't put your hand on it for more than a half second--sounds normal!

I saw in your carb settings you never mentioned changing the needle position.  If you are going to run pods it's pretty standard to simply:

1.  Change needle position to one higher (same as changing clip position to one lower).
2.  100 main jet to 110 main jet. 
3.  Done.  Leave stock jet as is.

Explain how you ordered PD carb slow jets from 4into1 when I have never seen anyone sell those except siriusconinc.  Also, why are do they have a 40 and not the proper 42 for your bike.  And if they do have a 42, why did you instead get 40?  PD slow jets are PRESS FIT, there are NO threads, if you have threads on your new jets, something is wrong.

I'm going to emphasize this because I don't think you're really aware of it, but the main jets importance is dwarfed by the importance of your needle clip and position.  The needle will affect ALL throttle ranges and DOMINATE everything from 1/4 throttle to 3/4 throttle.  Basically almost ALL your around town riding.  If you don't change it, you will also get hesitation off the line, which is what you describe.  If you don't change it, your engine will also be LEANER which means it's going to get HOTTER.

In regards to the smoke, the color of the smoke matters, otherwise we can't diagnose.  It could be something as simple as water vapor (white) or running rich (black), or oil leak (blueish). 

Pics of your plugs would also really help, instead of "seems like" analysis. 

Hope that helps and I will keep an eye on this thread to help you.

[Nestcraft]

Harisuluv,
Saying that my posts contain a constant use of the word "seem" or phrase "seems like" is not accurate.  The word "seems" was used a total of 3 times over the course of the ENTIRE thread (only once in the context you are stating) and you used a total of 3 times in your short post.... Hmmm, who has the constant usage issue? 

I purchased new #40 pilot jets because that was the size in the carbs already, as stated in previous posts, numerous times. 

They are available in a variety of sizes from both 4into1.com (keyster) and jetsrus.com (keihin)

http://4into1.com/keyster-keihin-slow-jet-honda-cb550k-cb750-1977-1978/

http://jetsrus.com/a_jet_kit_street/honda_550_CB550_1977-1978.html

Yes, I understand that the pilot jets were press in the minute that I pulled them out of the carburetor bodies and ordered new "press in" pilot jets.  As I said in my previous post this evening I have already switched out the pilot jets, thus, I would have known that.

I do know that these are air cooled engines...  I also have a 1973 Honda CB 350.  They get hot, I know... this was too hot.  Hot enough to almost stall the bike.  Without my help on the throttle it would have.

I seemed extremely fixated on the "overheating" issue becuase THAT WAS THE ISSUE!  No, the bike never got so hot that the cylinders locked up... if that was the case this thread would be reading a lot different!  As stated in the original post I put 1,000 miles on the bike and it ran good.  I fixed some vacuum leaks and then things went bonkers and it started over heating.

I haven't verified the needle settings yet since the bike was running fine until last week.

I am pretty certain the light smoke is due to richness, it SEEMED like a black color but the bike wasn't "smelling too strongly of gas".

I will check out the needle settings next time I have the carbs off.

[DaveBarbier]

...going to pick up a Dyna in a week or two so that should smooth things out even further.

Don't be fooled into thinking an electronic ignition will smooth things out. Points can be easily made to run as smooth. Totally get one if that's what your plan is, but if you think, because points are an older technology, that it has some inherent rough running qualities then you're mistaken.

I also have a set of #118 mains, I may try those and see if the smoking gets worse and see if the responsiveness of bike picks up or falls off.  If it gets worse I guess could order a set of #110s...  I had #105s  installed previously, when it was overheating.

Next week I plan to do a proper plug chop, but is there something else that may cause some very minor puffs of smoke?  I need to replace the cam cover "o ring" gasket as it is leaking a bit, should I do the valve seals at the same time?  Can leaky valve seals create some smoke?

Definitely do a plug chop before some experimental main jet swapping based on smoke output.

Yeah, leaky valve seals can put oil into the combustion chamber to burn, but if you're not sure if it actually needs it then I don't see a reason. From what I've seen, leaking valve seals will create more smoke than a "Was that smoke out the tail pipe? What color was it?" diagnosis.

Lastly, I counted 4 "seems". I'd avoid being cheeky since the guy is trying to help you.

[Nestcraft]

Thanks Dave,
I have been l planning on an electronic ignition from the start of this project. ... yes,  it idles smooth with points,  just saying that an electronic unit is only going to make things more stable.   Especially since The had been some funky timig issues lately.

As previously stated I am planning on a chop next week.  I took the bike for a spin this morning and it ran great,  light smoking coming off idle when revving and it does smell a tiny bit gassy.  So,  obviously it is running rich,  a chop should tell me where.

[DaveBarbier]

Thanks Dave,
I have been l planning on an electronic ignition from the start of this project. ... yes,  it idles smooth with points,  just saying that an electronic unit is only going to make things more stable.   Especially since The had been some funky timig issues lately.

As previously stated I am planning on a chop next week.  I took the bike for a spin this morning and it ran great,  light smoking coming off idle when revving and it does smell a tiny bit gassy.  So,  obviously it is running rich,  a chop should tell me where.

Cool, sounds good. Are you still able to start it cold without choke? If so, to me, and I hope Harisuluv agrees, that that's still too rich. But I'd do what he mentioned and verify and/or change needle position. Pretty much whatever he says I would do, haha.