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Topics - ManicGTI

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1
CB350/400 / Progress - She runs at last! (75 CB400F)
« on: October 31, 2016, 01:59:07 PM »
So, big progress for me.  After 20 odd years since it's last road tax, I have got her ('75 CB400F) started for the first time since my top end rebuild!  Thanks to all that have reponded previously.

IT STARTS!

Literally on the button, first attempt, with Choke open or closed.  Very happy about this! However I'm far from out of the woods.
- Appears to be running very rich (all plugs immediately / consistently blackened)
- Revs increase dramatically when I try to open the choke.

What's changed since my last attempt:
- Carbs stripped and rebuilt (again), bodies simmered in a pan for an hour or so with a dishwasher tablet, then recleaned with parts cleaner spray and went over all ports blowing and checking (concentrating on idle circuit).
- Re-Bench synced them, this time doing it in the 'closed position' rather than open.  Used a 4mm drill bit as it was what I had to hand, maybe I should have gone for 3mm as closer to the 'interweb recommended' 1/8".
- Also rechecked/adjusted Tappet clearances, Points Gaps, and Static timing.


So, any thoughts on what to do next?
- Check timing with timing light now I can run the engine.
- Redo carb Static balance?
- Idle screws?
- Try the OEM Idle jets back in there now the bodies are cleaned.
- Fit Hondaman transitorised ignition box (likely unrelated, but i'll fit it anyway)

Or is this likely to be something more fundamental, ie Rebuild kit jets not correct?  Carbs bodies still not clean?  REv counter isn't working, so not a clue what

At the very least this has renewed my enthusiasm so i'm keen to keep the momentum up!

Dave

For info, my previous thread:  http://www.sohc.co.uk/index.php/topic,9575.0.html

2
Recommended Sources for Parts and Services / WTD: Ultrasonic Carb Cleaning (CB400F)
« on: October 06, 2016, 06:09:42 PM »
Hey all, i've been away for quite a while as my 400 has been laid up in storage following a housemove.  I've just managed to get it back so onwards I can go again...

Does anyone have any recommendations for Carb cleaning services?  (Ultrasonic) I'm not sure it's the direction i'll be going in yet, but i'm fed up with rebuilding them, and I don't think I'm getting fuel through.  I'm worried that my 'hand' clean wasn't enough and the internal pathways are still blocked.

Thanks,

Dave

3
CB350/400 / Coaxing life out of the old girl...the second attempt!
« on: January 31, 2016, 10:53:26 PM »
Ok, so this is my second attempt at coaxing life into the four ('75 CB400F).  It's never run in my ownership...and here we are at the second attempt after finding a broken valve:

What's been done since my last attempt:
- Replaced knackered piston and valve, cylinder hone, new rings, lapped in all the valves.
- Tappet clearances set.
- All four Carbs have been rebuilt with cruzinimage rebuild kit.
- Float heights ~21mm.
- Gapped both points.
- Start attempts with Choke closed, No throttle and Full Throttle, no Airbox, Exhaust refitted.

So what was the result?:
- Turns over on the starter fine (but battery runs out of steam quickly)
- It did 'splutter' once or twice randomly, but didn't 'run' at all.
- Dry Compression test on the starter gives all 4 cylinders at approx 100psi, I believe this is acceptable.  New rings so they won't have bedded in yet.
- All 4 carb bowls are filling with fuel, no leaks. 
- I'm getting spark at all 4 plugs.
- No visible fuel on the spark plugs, as the carbs are filling now, I had thought this would be more obvious?


TO DO:
- New Battery.  Battery is a small one that Isn't holding charge and doesn't last long when turning it over.
- New Fuel.  The fuel is now a bit old as it's sat in the garage, so i'll swap that out next time i'm up, I drained the carbs in the meantime.
- Check Cam timing isn't 180 Deg out, I did check but I'll do it again.
- Ignition timing check,  I don't see how I can get this massively out as the points plate only bolts on one way, or am I missing something here?

Is there anything obvious i'm missing here? I thought at this stage I would be getting at least stuttering/bad running.  I get that my carbs likely need setting up properly, I've set them to the basic bench setup as per the Workshop manual.

Thanks for any input in advance, always appreciated!
 :(
David

4
CB350/400 / Leaking Carbs after rebuild - T-Piece O-Rings? (Resolved)
« on: January 11, 2016, 05:25:37 PM »
Having faffed around with my carbs a few times in the last year, I've ended up rebuilding with all new O-Rings, Jets, needles, float valves etc and it appears I have eliminated the 'overflow' leaks...

However, I hooked up the tank to them yesterday and I'm still getting a leak.  It appears to be central, and mainly coming from the central fuel supply T-piece.

Is there any particular technique/trick to sealing these up?  As a first pass I'm going to separate the carbs and try a bit of Silicone Grease.

Thanks,

David

5
Misc / Open / Engine services - Rebore/hone in London?
« on: July 13, 2015, 02:24:26 PM »
As it says really, I'm looking for recommendations for a reliable engine shop in London to rebore/hone CB400F Cyl Block.  I'm based in North/East London (around Islington/Dalston) but work out West in Staines.

I've found loads of places out of town, but there must be somewhere localish I can take it to?

Thanks in advance :)

David

6
CB350/400 / CB400F Frustrations - Not firing, low compression (Cyl Block now off)
« on: April 28, 2015, 02:21:34 PM »
EDITED title to current status.
----------------------------------

Ok apologies for the lengthy post!  I'm having difficulty coaxing any kind of life out of my CB400F.  Not a massive surprise as it was last taxed on the road in the mid-90's!

I'm really looking for a bit of guidance on an order of attack...what to check next and in what order, all advice welcome!

Intro thread and background to the bike: http://www.sohc.co.uk/index.php/topic,7399.msg44632.html#msg44632

I understand that there's a ton of things that need checking over before the bike will likely run 'well', but as a starter for ten I was expecting for it at least to attempt to fire up...It's turning over but it's not even trying to splutter into life :/

Status so far:

FUEL SYSTEM:
- Carbs were gummed and locked up.  Following advice on here I left them in hot water to loosen, then stripped and cleaned them with carb cleaner, including jets etc. Replaced all O-Rings along the way.
-  On reassembly the bowls leaked badly.  I've bought a rebuild kit (non-genuine) and replaced the Float Valves and pins, but left all the other parts as the OEM ones at the moment.  On reassembly (3rd/4th time lucky!) now only one of them leaks.
- Tank cleaned, new petcock, fuel hose, in-line mini filter and some fresh fuel.
- The carbs are roughly synced on the bench, but not balanced properly, just rebuilt as they were.  I have not put the airbox or filter back on.

ELECTRICAL:
- Checked Continuity across the starter circuit.  Clutch switch is duff so I have bypassed it with a jumper in the headlamp for the time being, now cranks on the electric starter perfectly fine.
- Checked continuity of Ground side of Coils and Engine Stop Switch circuit.
- Both Coils input sides appear to have a resistance of ~ 5.2 Ohms.  A couple of the HT leads havd kneckered ends so I trimmed them a little and refitted the Caps.
- Battery is new but admittedly undersized as I was planning on relocating it.  Its an AGM Fireblade battery, I have it sat on an optimate so it has full charge.
- Brand new spark plugs fitted.  All four are getting a visible spark when I crank with teh plugs lying on the head. 

My feeling at the moment is that no fuel is getting into the engine, I can't see any fuel on the plugs.  However, I've tried cranking it with some easystart into the carbs and not even a splutter.


TO DO:
- A 'proper' compression check, adaptor for my compression tester is ordered.
- Check static timing, although I cant see why this would be out.

Other things to check?
- Valve clearances, will this make a difference at this stage of things?
- Pull the carbs, clean again and replace idle jets etc with those from the rebuild kit?
- Anything else to check on the ignition system?

Dave

7
CB350/400 / CB400F - Rear tank mount
« on: November 06, 2014, 04:49:31 PM »
Hi guys, it's my first post (after intro thread! so go gentle ;)

For ref, the bike is a 1976 CB400F.

Does anyone have any, or can take, some detailed pictures of the rear tank mount/clamp arrangement?

The bike came with the Tank, but loose, with no Seat unit, Rear mudguard etc.

I haven't settled on a definite plan yet but I'm considering making a custom seat unit for it.  Before I do that I want to understand how the OEM set-up clamps the rear of the tank so I can either replicate it, or come up with something else.

It's not clear from this at all:


And the seat pan itself doesn't appear to have any specific mouldings or features?


Thanks,

David

8
New Member Introductions / '76 CB400F in SW London
« on: November 06, 2014, 01:23:22 PM »
Hello all!  I'm Dave, based in South West London....I've copied this over from http://forums.sohc4.net/!

I thought I'd register as I've just bought a '76 CB400F that will likely need a lot of work to get it back on the road...so I'll probably be loitering around the tech sections asking stupid questions...

My small fleet current consists of my '10 Street Triple R and a Turbo charged NA MX5 (Miata).   If I want to hit the track or go quick they do the job nicely so I'll admit this project is not about speed or performance, but more about having something fun I can get road worthy over winter and potter about London on.

So, the bike. It's a 1976 CB400F, it hasn't been run in over 10 years (likely more), missing a few bits but mechanically 'mostly' there.

It turned on the kick start but other than that I didn't dig into it too much, looks to be an 'honest' unused bike.  I'll admit this is a bit of a gamble as I have no clue of it's mechanical condition...but where's the fun in that?

So I've done a cheeky service to get started.  New smaller format AGM battery, plugs, oil and filter.  Happily it still had all it's oil, albeit ancient.  I've cranked it over a bit to get the fresh oil around the system and seems to turn over fine.

Nothing spectacular to see so far...carb O-ring kit and Fuel petcock on the way so I can hook up the tank and give it a start attempt.

As it came (Tank not shown):


A quick wipe over and basic service:


And the Street R:


:)

David

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