Odd 1975 CB360T noise

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Duff360

New Member
I pulled this bike out of a shed where it sat for years, got it running real good, put around 2000 miles on it since and it's been a great problem free bike, but it's always made this noise at 5500rpm, only when hot.. Sounds like a grinding, rattling, spun skateboard bearing kind of noise.. Only at 5500, when its cold I can ride up to 9k quiet as can be, and it's still quiet as can be when hot, until it hits 5500, even after 5500 it quiets back up. I've done the tensioner adjustment, and valves.

Some other things I've noticed, when kicking it dry I can feel and hear the electric starter spin, but when it's running not, normal? Also get some popping/puffing at idle on only decel on right exhaust but I think it may exhaust leak. Other than that no misses all the way to 9k. I normally shift at 5k all day long no problem to avoid noise.

I'm planning to ride this bike from South Carolina to California so trying to get it right before hand.


Thanks.
 

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Welcome,
The popping on decel to idle, is usually caused by a rich mix condition.
Is your air filter in good shape, have you tuned the adjustable air/fuel mix needles on the carbs, according to the manual?
Also this adjustment should be performed w a hot engine.

The engine noise I just dont know. I would start w the starter clutch first though. Make sure nothing is broken or missing from it. and make sure its allowing the crank sprocket to spin freely when not engaged and "locks" instantly and tightly when starter is employed.

Also when adjusting tensioner. Do it with the engine hot, and trap the crank w a wrench on the rotor bolt.

Valve adjustment should be done with the engine cold.
 
Authoritative source.
http://www.mikuni.com/fs-tuning_guide.html

Some Mikuni carbs actually have a vacuum operated auxiliary fuel valve that meters extra fuel under high vacuum conditions in order to minimize decel popping.
 
If you have your idle/pilot mixture set a little lean, they will pop on decel, mine does it because I changed my pipes and I don't feel like changing the jets to compensate for it. Not gonna hurt anything. Doing it on one side just means one of to things, that side is off on that mixture setting or the carbs need to be synced.

IF you are planning on riding that bike that far, depending on your skill set when it comes to bike mechanics, you should have it gone through completely by a competent mechanic, be that yourself or someone that knows vintage Hondas inside and out.

Either that or get a good roadside assistance package.

If you haven't already, get a good copy of the shop manual, its available for download in quite a few places if you google it. Go through that bike from top to bottom following the manual.
 
I've got a manual and read it, the bikes got great compression, and if its lean, why do the plugs look more rich. Plugs are brown, with carbon. Not oily. This grinding noise is just weird, doesn't do it at all for the first couple miles then it starts up.

Did the mixture adjust, right side is turned all the way left side mid. Doesn't pop at idle just on decels.

Electric start doesn't work anyways, bad solenoid so I'd like to just take it out the equation all together eventually.
 
Go back and read the link I provided.
You don't get a plug reading from "closed throttle/high RPM" which is the specific condition of leanness that causes decel popping. It does not mean your bike is running lean. It means closed throttle/high RPM popping is a lean condition.

<<Did the mixture adjust, right side is turned all the way left side mid. >>

What? That is definitely wrong. I don't know what you mean by "turned all the way," but if you are talking about the idle mixture screw, and you have it all the way in, you definitely have a tuning issue. That screw should always be between one turn, and three turns out from lightly seated. I generally start with the screw 1 1/2 turns out from seated.

Intake leak can cause decel popping, (lean during high vacuum.) Leaking exhaust gasket can cause popping, too.

If your plugs are brown, you are running a little on the rich side. Hard to tell what part of your throttle range is too rich. Could be main jet, could be the slide needle. To get legitimate plug readings requires doing a "plug chop." Read up on that one. I am not a big fan of doing plug chops. It works as a tuning method, but it's a pain in the ass pulling over at the side of the road to pull a hot plug from a hot engine.

BTW: You can get a replacement solenoid for like $15 on Amazon or at the auto parts store. You don't have to buy Honda's overpriced version of it.
 
Cool thanks I'll hit up an auto parts store for a solenoid, I could put a screwdriver and arch it to get the starter to turn so I figured solenoid going out.

To pull starter clutch do I need a gear puller? It's behind the stator right?

Man I posted this on the Honda twins forum over a week ago and no one responded, come on here getting good response. Thanks!


Like I said I put like 2200 miles on it on its current configuration and it pulls good and rides good for a 360, doesn't miss a beat or pop through carbs (I just came off an old 1000cc ironhead but I wanted something quieter and slightly more reliable).
 
Off the subject...sorry! What part of SC are you? I'm in Charleston. If you're close by and need any help...LMK. Good luck with the bike and the trip.
 
Could be corrosion in the starter button, too.

You need a puller to get the rotor off the end of the crankshaft. The puller is pretty simple, IIRC. Sort of just a fat bolt.
 
mwm1977 said:
Off the subject...sorry! What part of SC are you? I'm in Charleston. If you're close by and need any help...LMK. Good luck with the bike and the trip.
Click to expand...

Summerville, close!


I've been thinking it was the chain tensioner so I've been beating mysel looking for one but if its the starter clutch that'd be great then I don't have to tear apart the top end.. But if it was the tensioner I'd hear it on all rpm I figured.

Could there be any significant damagecaused by the starter clutch being bad? I've ridden for 2000 miles like this so just wonderin.


Could I do a whole starter delete on this thing? Kicking is effortless on it compared to the Harley so it really wouldn't bother me. What would I put in place of starter clutch
 
Duff360 said:
Could I do a whole starter delete on this thing? Kicking is effortless on it compared to the Harley so it really wouldn't bother me. What would I put in place of starter clutch
Click to expand...
.

Look at the link I posted. Its all about the starter and starter clutch. You dont need no puller.

sorry bout the mis info,it was early.

On the stock cb360, keihin carbs, air/fuel screws in = leaner...out = richer.

btw which manual have you read?
 
I have a clymers, came with bike. I used to work on old Harley's so this is a little different. Def replacing all these Philips bolts with Allen's when I open it.

So with the starter clutch. All that looks easy enough, do I just toss the whole clutch assembly and bolt the rotor back on?
 
yep if your looking for kick only. You can get the plug on here from crazypj, he makes really nice 360 specific ones for the best price around. he made the one you see in the pics. I believe he just posted getting fresh stock in for making more plugs the other day.
Also, the Clymers is a worthless piece of shit for the 360. Just compare the entire carb section in the clymers to the carbs on your bike. Honda never made any 360 w the carbs they show in the Clymer manual.
The manual I offered to you for free is the Official Honda workshop manual for the 360.

and they are not phillips heads, they are JIS heads. thats why the phillips driver you use tear them up so easily.

Be sure to use the lubricant of your choice on the SS hardware your planning to add, to prevent galling.
Galling post...
http://www.hondabrat.com/2012/11/galling.html
 
I actually planned on just keeping the starter bolted on, it's got stripped heads holding it on and really not trying to bother with it. I'm going to take the chain off and starter sprocket and then gut the inside of the starter clutch and put it back together and hope that damn noise is gone!

The carbs in clymers do look like my carbs. Vacuum cvs? Looks like a Harley cv but smaller.
 
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