CB360 Carbs and Reliability

cb360j

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My 360 is frustratingly unreliable. Riding in town just isnt feasible because the bike will randomly die, so I am going to redo everything. Its going to start going through a strip down this week for a repaint and a tidy up. PJ modded the carbs to accept pods, and i can nail down the timing perfectly with a timing light but it never runs quite perfectly.

Are there any carbs, mikunis or otherwise, that can help me reach a better reliable state? Or should I keep with the stupid stock ones that get the slides stuck every couple weeks?

Thank you in advance for any help
 

trek97

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The holes in the slides must be oriented towards filter side. Remarkably, they will twist around in the diaphragms over time. If they are not in the correct orientation. The slides will "hammer". Hammering deforms the bottom outside edge of the slides, this deformed edge will cause them to stick. AND it sure dont take much deformation. So inspect the edges very very closely. You can carefully file or sand away any bad spots and fix them. Also, adding just a capful of marvel mystery oil to the fuel tank every fill up will help lube sticky slides. I used to have a pic of "hammered" slide damage. But that was years ago. Ill take a look.
 

ridesolo

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I can tell you that when I was using my 360 as a commuter on a pretty much daily basis there was, simply, no reliability issue, period. I’d go out in that morning and it would start. It ran good and all I did was add gas and change oil. Even after sitting all winter the only difference was that it took a bit more cranking to get it to start up the first time. Something is off setting or torn or cracked or worn out and I’m pretty sure that once you figure out what it is and get it corrected you’ll be good.
 

cb360j

Member
The holes in the slides must be oriented towards filter side. Remarkably, they will twist around in the diaphragms over time. If they are not in the correct orientation. The slides will "hammer". Hammering deforms the bottom outside edge of the slides, this deformed edge will cause them to stick. AND it sure dont take much deformation. So inspect the edges very very closely. You can carefully file or sand away any bad spots and fix them. Also, adding just a capful of marvel mystery oil to the fuel tank every fill up will help lube sticky slides. I used to have a pic of "hammered" slide damage. But that was years ago. Ill take a look.
I always orient them back in the direction of the filter that you told me to do in one of my other threads, then of course to fill and smooth the edges. For some reason it just happens over and over. That picture of the hammered edge is in my thread as well
 

cb360j

Member
I can tell you that when I was using my 360 as a commuter on a pretty much daily basis there was, simply, no reliability issue, period. I’d go out in that morning and it would start. It ran good and all I did was add gas and change oil. Even after sitting all winter the only difference was that it took a bit more cranking to get it to start up the first time. Something is off setting or torn or cracked or worn out and I’m pretty sure that once you figure out what it is and get it corrected you’ll be good.
Thank you, that's good to know that they can be reliable. I generally like to assume it is me that has messed something up.
 

Sderbyshire

Into Sailing, classic Triumph cars and motorbikes.
My 360 was also reliable on standard carbs even after i converted it to a 390 !
 

trek97

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Since PJ modded the carbs it will run better than new, if you re-fit stock airbox and filters.
Its exactly what I did. IMHO I think they look better with them. Not to mention...more fun to ride than push.

Every blue moon mine would die on 65mph deceleration to a stop sign. didn't bug me too terribly much. But still it would happen.

Now...

Screen Shot 2018-02-17 at 9.40.50 AM.png


Before...

IMG_0023.jpeg
 
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trek97

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I always orient them back in the direction of the filter that you told me to do in one of my other threads, then of course to fill and smooth the edges. For some reason it just happens over and over. That picture of the hammered edge is in my thread as well
Did you install fresh new OEM honda diaphragms? Or the completely shitty aftermarket ones?
If you installed the completely shitty aftermarket ones...Im 20000% certain they are your problem.
My bike was unridable w those...did I mention they are completely shitty?
I wrote the company and asked if they had any other reports about them. They replied, "Dont matter, They sold a million of them- If Im having trouble it my problem" or something like that. Nice good guys.
Making no other changes, I installed the OEM diaphragms. It instantly ran perfect the moment I hit the starter button.
 

trek97

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Its been a long time and too many bikes ago, I think they were JBM diaphragms? Sound right maybe?
I probably haven't ridden my 360 in two years, but I guarantee I hit that button and it will purr, right now.
Its all in good filters and diaphragms.
 

cb360j

Member
The diaphragms I used were from common motor, are these bad? And when pj did my carbs he installed them for me.

Also, I would love to run the stock airbox and filters and side covers as I also think they look so much better but when I first got the bike... like an idiot... i ground off all the mounting tabs for the side covers. But dont the stock filters mount on a little tab right behind the frame by the carbs? I think i left those.
 

trek97

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The diaphragms I used were from common motor, are these bad? And when pj did my carbs he installed them for me.

Also, I would love to run the stock airbox and filters and side covers as I also think they look so much better but when I first got the bike... like an idiot... i ground off all the mounting tabs for the side covers. But dont the stock filters mount on a little tab right behind the frame by the carbs? I think i left those.
PJ eventually steered clear of the JBM brand, also. And its his son, Brendon? owns Common motor. I believe. So I would "assume" the ones you have are not JBM brand.
Its Honda or nothing for me. I won't waste $ I could put towards the Honda ones on something less.

I did the same...cut off the tabs. I just made up some and welded back on. Different years had different style air boxes. the 76 filters are no longer available...but I got NOS filters on the shelf to last my lifetime, if I start riding it every other day. The 74 style are readily for sale...common motor sells them. You need the necessary cross over tube that was incorporated into the battery box and "pinches" between the filter boxes. (keeps the air pressure the same between the boxes...if one filter gets clogged it will keep running good (drawing off the other).
You can just make one of the cross tubes up from scrap sheet aluminum or whatever, some jb weld and pop rivets. None of it will show...just spray it all black. Easy Peasy.
 

trek97

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The lack of the cross over tube is probably one of many reasons why pods are just the worst idea, for the vacuum slides. The air pressure is not kept the same between the carbs. So they may always try to be running a bit different. Say if one pod has even a bit more oil in it...they will draw air differently.
 

irk miller

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You could run a crossover on the intake side. I have a crossover tube on my XS650 intakes.
 

cb360j

Member
Do you guys mean crossover for the fuel line or for the air intake?
I tried to find a picture is your xs650 build, but not sure you posted one irk
 

irk miller

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Yes, crossover on the air intake is what Trek is talking about. My XS has them on the intake boots. The fittings are there so you can vacuum sync, but I run a tube from fitting to fitting. It would require experimenting, but I wonder if a crossover from carb to carb, either through the vacuum ports or added to the intakes would balance them out. It does on my XS.
 

cb360j

Member
Yes, crossover on the air intake is what Trek is talking about. My XS has them on the intake boots. The fittings are there so you can vacuum sync, but I run a tube from fitting to fitting. It would require experimenting, but I wonder if a crossover from carb to carb, either through the vacuum ports or added to the intakes would balance them out. It does on my XS.

Do you remember what the original crossover tube looks like or where to find one? Could I use a rubber vaccum tube? I have the factory air boxes and filters (trash) and the hardware to mount them. If i can weld on some tabs for holding them on and for the side covers I might be able to get those parts working again.
 

trek97

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Do you remember what the original crossover tube looks like or where to find one? Could I use a rubber vaccum tube?
"D" shaped outlet on back sides of filters/boxes.
As I wrote earlier and above....

"You need the necessary cross over tube that was incorporated into the battery box and "pinches" between the filter boxes. (keeps the air pressure the same between the boxes...if one filter gets clogged it will keep running good (drawing off the other).
You can just make one of the cross tubes up from scrap sheet aluminum or whatever, some jb weld and pop rivets. None of it will show...just spray it all black. Easy Peasy."
 
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irk miller

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this is a very interesting thought.
My XS breathes well. I'm not sure it will help if it doesn't. The tendency will be to draw where there is less resistance. If there is extra air to give on the non-clogged side, it should help. If the engine pulls max air with perfect filters, then I can't see it helping. I have a hard time believing the engine is pulling all available air, so I suspect it will help keep the intake balanced. We're also talking about a small 1/4" tube on the XS, with tiny openings on the fittings. Not sure how much it's really getting.
 

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