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Messages - Alexrayz

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1
CB350/400 / Re: Need to check out a slight misfire when cold
« on: Today at 02:06:42 PM »
Quote from: Mikep328 on Today at 12:42:40 PM
Did an ignition check - changed wires but no change to cold pipe.  I pulled the spark plug, laid it on cyl head and re connected wire - good strong blue/white spark at cranking speed.

So it might be the carb slightly out of sync though they were carefully bench synced when cleaned several months ago.  But still not sure why there would be poor fueling for 30-40 seconds when cold and then clear up on its own and have no such symptoms on restarts for the rest of the day and idle smoothly at 1100 RPM.

I might pursue it a bit more but since it has no effect on the actual operation of the motorcycle within a minute of cold start up, I won't lose much sleep over it.  However, I do admit I like things to work as they should so I suspect I will continue to futz with it! ;)
If you let the bike stand for over 3 weeks there might be some ethanol clogging the jets.


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2
CB350/400 / Re: Need to check out a slight misfire when cold
« on: June 16, 2024, 01:07:20 PM »
Hey there!

Could be multiple things, mainly an imbalance between this cylinder and the other ones.

Carburetor wise it could be:

- Bad air fuel ratio at idle = play with the mixture screw on the side of the carb acting up. Mark where it was before you started playing with it, otherwise you’ll get lost and miss a reference point.
Turn by 1/4 turn increments while idling. You’re looking for the best performance, meaning for when the engine idles the highest. If the RPM falters that means it’s getting out of stoichiometry.

Bad sync = The slides don’t all have the same height meaning not the same amount of fuel+ air at any time, maybe more prominent with the choke on. Follow the synchronisation procedure. If all the gauges read the same depression all good.

Fouled jets (ethanol gum up) = Requires taking out the carb ramp and dismantling and cleaning which sucks.

Bad fuel inlet valve or float height= ditto

Spark plug wise:

Bad gap or electrode wear.

Checkup :

Check plug for not chocolatey color: If black or sooty —> Too rich
if white or pale —> too lean

Word of caution: Anything that involves fiddling with the carburetors can be finicky, counter intuitive and possibly worsen the performance if you’re not careful or experienced enough, talking from experience: I had to have a mechanic reset everything because I messed around without proper method and knowledge.


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3
CB350/400 / Re: Do I clean the pistons or replace them
« on: June 11, 2024, 05:26:30 PM »
The rings are here to separate the combustion chamber and the oil lubricating the piston. Busted rings would result in oil burning in the chamber, which is signalled by a blue smoke at the exhaust and the oil level dropping over time. Other result is a loss in power as the compression goes into the crank (seal of the rings gone).
As the lubrification is compromised the pistons can end up grinding against the piston sleeves, so vertical grind lines on the sleeve can indicate poor lubrification and so busted rings.
 Also if your rings are broken well then clearly they need to be changed.

If you haven’t noticed anything then no need to undertake changing your rings.  Again if you want to check that all is well you can refer to the shop manual where you’ll find the ring’s tolerances and check that out


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4
CB350/400 / Re: Do I clean the pistons or replace them
« on: June 11, 2024, 04:57:28 PM »
If it ain’t broken don’t fix it.

I’d be interested in what the numbers mean but it is not necessarily a piston order.
Maybe it is the stamp for the mold reference, so that in case of a manufacturing defect you can easily spot the faulty mold. You can see that on many cast products.

Not saying that is the explanation but it could be one.

Either way if your bike ran fine don’t bother. Feel free to check their specs are within tolerances but yeah other than that refer to the first sentence of this message hehe.

Motorcycle maintenance can be tricky and stress inducing and we always assume the worst very quickly, but if there is an issue the bike will make it loud and clear.

Trust your senses and your smarts and keep cool!


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5
CB350/400 / Re: Do I clean the pistons or replace them
« on: June 10, 2024, 09:41:21 PM »
No need to replace it is just carbon build up. Giving them a clean is enough, as it has been mentioned before.

Are you running your engine at a low RPM usually? Something like bellow 3000?

I have been told that those deposits form when the combustion chamber temperature is slightly too low, that is when the engine is run at low rpm, whereas at higher rpm the deposits burn off, keeping the piston heads clean.

Something something italian tuneup


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6
CB350/400 / Re: 400/4 air intake assembley
« on: June 10, 2024, 09:18:54 PM »
Okay yup I see it. What Dave said. Also once the trumpet is fully in you can help the lip of the rubber gasket by pushing it from the inside of the trumpet. Either you can use your hand if it’s not too big or using something long and not sharp. That’s what I usually do and it does make it a lot easier.


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7
CB350/400 / Re: 400/4 air intake assembley
« on: June 10, 2024, 08:20:08 PM »
Do you mean you have trouble reconnecting the airbox itself or do you mean something else? Pics help if you have any.
Either way yeah it can be tricky but I would need more precisions to give you accurate advice.
Cheers!


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8
CB350/400 / Re: CB400F Oil pressure switch slow leak
« on: May 21, 2024, 01:08:22 PM »
Hey Julie thanks for the offer!

Are you sure about the postage costs to France? When I ordered my Hagon shocks I got something close to 80 euros in import fees...  >:( :'(

On a side note do you all have any idea what are the differences between the different switches available? The prices vary wildly, so I am curious if it is manufacturing quality or rarity or... etc

Furthermore, are OEM parts strictly better quality than aftermarket for these kinds of basic parts? I understand that the specs would be different between stock and AM for racing parts, but for basic general operation I don't know

Cheers!

9
CB350/400 / Re: CB400F Oil pressure switch slow leak
« on: May 20, 2024, 06:18:44 PM »
Hey everyone! I finally got to it.

I simply had the bike idle while the left cover plate was off to see where it was leaking from.
Surprise surprise it was the oil pressure switch again, from the switch to pump body thread AND from the eyelet screw thread on the switch itself,.
Guess I'm up for another switch, although I am not sure about which one to pick anymore.
I chose a new switch that is made today for several japanese/ asian automotive manufacturers. Honda lists it as the replacement reference for the original that was used in their 70's UJMs.
Those new switches are around 4 euros a piece, so it felt like a no brainer compared to the 40 - 70 euros originals on Ebay.
Now with the performance from the one  bought, I'm having second thought. Because the cherry on top of the crap cake is that the oil light came on like a minute or 2 after the bike was turned off.
Doesnt look like a quick switch to me, unless the oil does stay pressured well after the pump stop turning (???)

Looking forward to hearing from you all. I hope you guys get good weather!

P.S. : I found out that a motorcycle that won't turn over could be in need for petrol. Whou would've thought? I was already considering taking off my carbs for a clean  ;D ;D

10
CB350/400 / Re: CB400F Oil pressure switch slow leak
« on: April 20, 2024, 04:06:56 PM »
Hey everyone,

I haven't taken a look yet, I have been mainly investigating on the web. Will keep you updated

Cheers

11
CB350/400 / Re: The 'Correct' method to adjust the 400/4 cam chain tensioner?
« on: April 11, 2024, 12:53:12 PM »
For reference I use the revue technique moto for the Honda CB400F and Norton Commando.
They do say to use the idling engine method.
What I have read elsewhere is that if your horseshoe is binding or the spring is old the conventional method doesn’t work, as there is too much resistance for the spring and stem bit to set the slack correctly.
The fix is to use the « engine off , screwdriver inside » that you described.

I don’t have the shop manual right now, maybe there is something on there?

Anyway here was the information I have. I need to adjust the chain soon so I’ll keep an eye out ;)

12
CB350/400 / CB400F Oil pressure switch slow leak
« on: April 11, 2024, 06:56:30 AM »
Hello ladies and gents!

A year ago I had a slow oil leak at the oil pressure switch thread.
When running at temp I would lose a drop or two every five to ten minutes.
A degreased the oil pump housing, switch and the threads before putting
yellow loctite (577) on said threads.
It worked for 300km and started leaking again.
So I got a new switch. Turns out the OG one has replacements currently manufactured
and fitted on modern japanese cars. So yeah no need to spend 60€ for a used one on
Ebay as I previously thought.
Fitted said new switch without loctite (Wasnt mentioned in the holy book)
Then I tightened it as much as I could, that is until I got scared to strip something.
The bible does give a torque setting but impossible to fit a torque wrench in there.

3 months have passed with small rides, I washed it thoroughly for the first spring ride.
Still leaking a drop or two.  >:(

Have you fine people run into similar issues?
I would like to read your thoughts and opinions on the matter, maybe make this topic a compendium of OPS issues and fixes, who knows!

Cheers from across the channel! 8)

13
CB350/400 / Re: Re-threading carbs?!
« on: January 30, 2024, 09:31:15 AM »
Hey everyone, I am resuscitating this thread to give an update on the bike.

Carbs were fine, even more so with Al’s OEM jets.

The issue was the previous owner did an extremely poor job of cleaning the cylinders… It was more of a rebore at that point.
So much so that the pistons can wiggle somewhat… As a result there was almost no compression, cylinder 2 got 0,72bar for instance x).
 It goes to show how well these old things were built as it still somehow managed to tick over.

Anyway, this was way beyond my skill and equipment level so I had a local shop (Rolling Moto Le Mans) do a full diagnosis and rebuild. 
Sounds a bit overkill, but I already had spent a lot on repairs and figured it’d be best to just get everything done once.

Cost me a pretty penny (3k in total) But it is good as new now, with a kicker:
It was so overly bored out, it needed to be refitted with a big bore kit haha! So it is a 450 now and it purrs like a kitten!

I’ve been running it for a year now and apart from a bad oil pressure switch it’s been a good sport.

Yipeee!


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14
CB350/400 / Re: Honda CB400 wiring connectors
« on: March 16, 2022, 12:19:03 PM »
They are japanese connectors, different from bullet connectors or fastons. In EU I usually find them on classic/ vintage automotive parts shops. Maybe you can find them in specialised electrical automotive shops?

15
CB350/400 / Re: Washer Light Case
« on: January 27, 2022, 07:07:13 AM »
Looking at the rectifier connector pic it seems things got heated. There is a possibility that there is a short. When investigating electrical, I recommend printing multiple copies of the wiring diagram of your bike (careful as there are different versions) and mark with a fluo pen the different systems on different copies: like 1 copy is the blinkers, another the coils, etc. Helps making a mental map.


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