CB360 Maintenance

Well I had another post about the cam chain adjustment (http://www.dotheton.com/forum/index.php?topic=60881.0) Got great help.

Since I'm not doing a break down I'll keep this thread active with pics to log my maintenance/tuning/etc. on the CB360. If there is a better location please let me know and I'll move it.

Main issue now is getting rid of the missfire/stutter at around 4K-5K when cruising. Accelerating through this works great and at higher RPM it is great.

Things I have done so far:
1) Cam chain tension: Checked the cam movement and it looked great, no slack or lag when turning the crankshaft.
result - no change in stutter. But I think it was quieter, hard to tell.

2) Valve adjust: checked intake at 0.002" and exhaust at 0.003". No adjustment, both sides seemed the same. It is hard to tell with so little room and very small gaps. My worry was they were too tight and preventing the valves from closing fully. But I could definitely feel a little play when the valves were closed.

3) Points & static timing: First checked the timing, it was a little late (1-2 deg.) on both left and right. So I decided to pull the points plate to check the advancer too..

Points plate before removal (points-pre.jpg): looks good to me.. this is the first I've seen though in person...

Advancer (advancer.jpg): Also looks fairly clean, springs intact. There is a little play when springs are loose. Is this normal?

Inspection of left and right point (point-left.jpg & point-right.jpg): There seemed to be a little marking in one area on both points, didn't notice any pitting. So I cleaned up the points with some 400-grit black emery paper, then used clean plain paper to pull through until clean. I've read to never use sand paper, use a point file and also that emery paper is ok. I tried a small metal nail file, but was not working well, to big. I didn't remove the points from the plate. I re-installed, adjusted gaps, did the timing and got very close to bang on.

I also added some Seafoam to the gas and oil.

Result: I think it is better. Certainly feels like less stutter. It idles and fine (same as before, maybe smoother), and pulls great when opened up (same as before). When cruising around the 4K-5K range it is still stuttering a little. I took it out for a couple hours and I think the stuttering slowly got worse, not sure. I think it still feels better than before.

My goal is to get rid of the misfires/stutter so the bike fires on both cylinders through the whole range consistently.

My next maintenance & plan to resolve this:
1) Change the oil... after the Seafoam in the oil they suggest this. And I did notice it was darker after the ride, so maybe something is being cleaned up.
2) Remove the points completely and clean them really, really well, and use paper with Acetone to get rid of any oil & residue. Any advice on point cleaning? (I will be ordering new ones too).
3) Find out source of spark plug fouling (sparkplug.jpg), Both look like this, I think this indicates way to lean - how to fix this?
4) Improve compression - seeing about 130&140 when warmed up. Is the spoonful of oil in the cylinder trick a good test to see if the rings are OK?
5) remove and check & clean carbs, replace boots (after the season)

Lots of fun & things to do. I usually do thing one at a time and measure the impact.

Cheers

Engine's a bit rich... Plug needs to be coffee-with-milk brown.

coffee with milk brown is still too rich you are thinking 2 stroke jetting
my 350 plugs run almost ghost white on the entire insulator,the ground strap is grey and it runs perfect

With a proper plug chop, the insulator should be WHITE, with a 1mm wisp of tan at the base of the insulator. You will have to chop your plugs with a grinder to properly inspect the base of the insulator. The base thread will also have just a wisp of fluff. Very light tan that you can wipe away with your finger.

Put a FRESH plug in the plug insulator and check spark when HOT. Check battery voltage when key off and then at 3,000rpm.

In addition to rich mixture, that plug looks like it could also be weak spark or poor compression. It should be at least 160 hot, so you are low on compression for sure. Make sure you test compression with throttle open or you'll get a false reading. Have you tested the coils too? Amongst everything else, are you making sure you're not grounding out at the points cover. These are notorious for it and the way your yellow wire is set up, it's probably pretty close to the cover. It would be really bogging down which you don't necessarily describe, but something to keep an eye on and check for anyway.

deviant said:

In addition to rich mixture, that plug looks like it could also be weak spark or poor compression. It should be at least 160 hot, so you are low on compression for sure. Make sure you test compression with throttle open or you'll get a false reading. Have you tested the coils too? Amongst everything else, are you making sure you're not grounding out at the points cover. These are notorious for it and the way your yellow wire is set up, it's probably pretty close to the cover. It would be really bogging down which you don't necessarily describe, but something to keep an eye on and check for anyway.

Click to expand...

Thanks for the feedback. I'll definitely reroute the points wires to make some clearance. The behavior of the bike when it missfires or stutters is a sudden loss of power, like someone is hold it back almost jerking it. I can hear the engine missing on one cylinder and feel it. It lasts for a second or two then fires normally for a few more seconds then misses. When it is happening I would say the ratio of missing to normal is about 25% misses, at its worst. Opening up the throttle and it immediately goes away and there is power.

I am worried about the compression. I've tested it a few times, when hot and throttle held wide open. only see about 140 best. Maybe it's the gauge (from Canadian Tire), was thinking of testing on the snow blower to see what it does.

Any recommendations on oil for this engine?

Cheers
Peter

Compression issues would appear first as dying at idle and burning of oil.

I've had bikes run at under 90psi. They just wouldn't idle.


Suspect electrical first.

pkoster said:

I took it out for a couple hours and I think the stuttering slowly got worse, not sure. I think it still feels better than before.

Click to expand...

Like all 360s she is running rich. PJ and I have been focusing our efforts to solve this issue.

It will run richer as it warms up. The hot intake helps to better atomize fuel. thats the reason you need to choke it when cold. And the reason it is cutting out more once it warms.

Do you have pods installed?

Do you have stock diaphragms or (aftermarket) JBM diaphragms?

AT 4000 rpm, Mine runs a little rich w old stock diaphragms, but no cutting out. (10.5 - 11 to 1 ratio) With the JBMs it drops down to 9.8 - 10.3 to 1. and starts popping.

A couple items that have helped to improve the reliability of my carbs...

new keyster float needles.

new keyster secondary/slide needles and seats. The original needles and seats showed some wear.

and adhering to this strict A/F needle adjustment procedure.

http://www.dotheton.com/forum/index.php?topic=60728.0

Hi Trek thanks for the feedback, some answers:

Do you have pods installed?

Click to expand...

No, stock carbs.

Do you have stock diaphragms or (aftermarket) JBM diaphragms?

Click to expand...

I don't know, never had them off or apart yet. However, based on the fact that everyting else on the bike is stock (I think) I would guess the diaphragms are too.

I was thinking about the stuttering issue, and though that when crusing (i.e. the throttle is not very wide open) the engine is trying to pull air through a restricted carb, thus more susceptible to air leaks in teh boots or diaphragms. Once I open the throttle the air flows more freely through the cards and less leakage.... but this is based on zero knowledge of the carbs on this bike.

Thanks for the info... it's making me want to take the carbs off and check them out. First I think I'll make sure the electrical is all good/perfect order. This I can do and not, potentially, sacrifice a weekend ride.

Cheers

Does the bike perform the same whether hot or cool?

All you have to do is check voltage at battery and use new plugs to see the condition of your spark. You don't even have to remove the ones installed.

If you suspect an issue with the carb boots, then spray some starter fluid around the boots to see if the idle goes up. Then you'll know if they are cracked and leaking.

deviant said:

If you suspect an issue with the carb boots, then spray some starter fluid around the boots to see if the idle goes up. Then you'll know if they are cracked and leaking.

Click to expand...

I've tried this a couple of time, sprayed all around the boots, no change in idle

As for the Spark - I'll check the voltage at idle & higher revs. I have some new plugs and will check the spark, try to get a video with garage closed and dark 8)

Thanks for all the advice.

Remove both spark plug boots from the installed plugs. Don't remove the plugs from the head. Insert new plugs and ground them to the engine. Find which points are closed. Turn the ignition to on and use something plastic or otherwise soft to open and close that set of points. Each time it opens, you can observe the spark for that side.

Rotate engine until other set of points closes. Repeat.

Don't leave key on for more than a minute at a time. A few seconds is ok.

Back from vacation and finally got around to checking some things on the bike:

Battery check:
- used a volt meter at the battery - basically get about 12.6 volts at most RPMs (12.2 at idle). So I RTFM again and noticed I did not disconnect the regulator. After some poking around I found it and it is not even connected to the system, the wires are just dangling loose. So I figure the rectifier must be new and include a regulator as well. I'll attach a picture once I get it off my phone.
- So I disconnected the rectifier and tested the voltage across the lines coming from the generator (Y & P in the Honda manual):
9.4V AC @ 1100RPM idle
25V AC @ 2500RPM
40V AC @ 5000RPM

I think this shows the generator is putting out enough voltage.

In short I think the battery & charging/electrical are OK, and not contributing to the missfire in the 4K-5K range. My next step is to check the spark - I picked up a new set of plugs, will check that next.

I readjusted the idle speed, hoping to lean out the fuel mixture. It runs OK but the missing/misfires are more noticeable. Also getting the pilot screw setting just right is very difficult. Seems like anything form about 1.5 to 3 counter clockwise turns produces the same idle.

I picked up the vacuum port connectors and a carb adjustment wrench from Flying Squirrel Motorcycle (Toronto) and will attempt my first carb sync soon. (need to make the manometer still) I do notice that the left exhaust is a little weaker (air pressure) than the right.

BTW after a long ride today I did a compression test again today and got 140 & 150 PSI (L & R).

So to sum up my action plan for resolving the 4K misfires is:
1) Verify spark is strong (not exactly sure how to quantify this)
2) check/set carb sync
3) redo idle speed - will stay on the lean side for the pilot screws
4) put new plugs in and recheck fouling - I seem to be perpetually rich (black dry plugs)
5) re-check tappet gaps
5) Clean points and reset timing again
...
end of season - pull carbs - check/clean/etc.

Any advice is welcome and needed and very much appreciated.

cheers

Spend $15 and get a Chinese lawn equipment tach/hour meter. It is accurate enough to detect a difference of 10RPM as you turn the idle mix.

Set the idle a bit low, about 850RPM. With the tach on one of the plugs, make sure you have it set so it is reading similar to the dial tach on the bike.

Both screws should be set to the bench setting.

Start on one side. Turn the screw out 1/4 turn at a time. Each time you turn, the idle should go up or down.

Here's the basic explanation. You want to keep richening the circuit until the idle doesn't increase. So if you achieve 1050RPM, wait 10 seconds and then turn out 1/4 turn and it doesn't go up OR it goes down, turn it back IN 1/8 turn and you're done. You want to be 1/8 turn OUT from highest idle to keep it on the fat side. Lean is a bad bad thing unless you want to test the melting point of your spark plugs.

Repeat for the other side. You don't have to switch the tach's signal wire to the other plug

Once you have set the idle mixture, sync the carbs. Don't sync at idle, maybe closer to about 4,000RPM. You'll notice if you sync at idle, they don't stay sync'd as the throttle opens.

Finally, set idle speed using the digital tach.

Don't bother doing ANY of the above until;
-The cam chain tension is adjusted
-Valves are adjusted
-Ignition timing is adjusted
-The motor is at RUNNING TEMP

You can usually get to temp by riding for 20 minutes. Once you are in the garage, keep a fan pointed at it.

trek97 said:

Like all 360s she is running rich. PJ and I have been focusing our efforts to solve this issue.
Do you have pods installed?

Click to expand...

pkoster said:

Hi Trek thanks for the feedback, some answers:
No, stock carbs.

Click to expand...

Not the carbs, the air filters. Stock air boxes (with 30+yr old filters) or aftermarket 'pods'?

crazypj said:

Not the carbs, the air filters. Stock air boxes (with 30+yr old filters) or aftermarket 'pods'?

Click to expand...

Stock air boxes & filters. One looks in very good condition (left), the other looks clean but some, maybe 1/4, of the material is roughed up, looks compressed and fuzzy. Ill post a pic.

Thanks Redliner for the feedback. I've ordered a digital tach as you suggested (~$18 from amazon). Will use this for future tunings.

Here are some pics:
(3) The air filter from the right side 3 images from various angles
Should I replace this (OEM or DIY with a FRAM cut up)?

(1) the rectifier:
Can anyone tell from the pic if this rectifier is stock or an aftermarket one that includes a regulator?

Thanks,
Peter

I always replace the r/r on these to improve charging and protect batteries. Those normally shunt at 15.5v. This Onan cuts charging to 14.4v max. It is both a regulator and rectifier.

That is your rectifier. Your regulator will look like a very small snuff tin or rounded box.