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Messages - Mr-Gear
1
« on: September 05, 2026, 08:45:01 AM »
Thank you all, the responses are appreciated. I am a little on edge because I had a failure (detailed in a previous thread of mine) during a trip in Europe where the bike didn't make it home.
Hopefully this post reaches others who may be wondering the same.
2
« on: September 04, 2026, 09:25:02 PM »
Hi All,
I have a rebuilt CB400F engine where the bores have been machined oversize to 51.25mm paired with 0.25mm oversize pistons/rings (pattern from DSS).
During assembly, ring gaps and piston OD was measured within spec.
Break-in procedure followed as per the Honda shop manual guidance using mineral engine oil, local riding working through the gears at various RPM ranges.
Since the rebuild and subsequent break in, the engine appears to be performing well and compression values are ~150psi evenly across all cylinders after what is now 2000 miles. There have been a few occasions where the engine has been held at at a constant speed on the motorway as I like to travel on the bike (I'd estimate 6-7K RPM for an hour or so).
Out of curiosity, I popped an inspection camera into the bores and saw that cylinder 1 has polished areas (perpendicular to crankshaft) at the bottom portion of the cylinder wall. (see attached picture). This feature appears across all 4 cylinders in the same places to the same extent.
Being magnified by the inspection camera could just be making it look worse than it is. I have not disassembled the engine to investigate further at this stage, as it is all nicely finished with Cerakote and I wouldn't want to risk damaging the finish unnecessarily.
Question:
Is this normal or expected?
If not what could be some suspected causes?
Is this detrimental to the engine?
Thank you.
3
« on: October 31, 2024, 03:07:31 PM »
Hi all, to answer some additional questions 1. My own suspitions similar to others is lean condition and detonation which deteriorated the pistons and ultimately the piston rings. since the top ring is gone on cylinders 2 & 3. Cylinder 3 has damage to the same type and extent as cylinder 2. Cylinders 1 and 4 seem ok and no visible damage but do look like they have been hot. All pistons will be replaced and all cylinders will be inspected and reworked. 2. Thank you for the link K2-K6. I have read that post before and I think even replied to it. I'd like to think I learned from the information provided and It did influence my riding style but perhaps I didn't adjust enough. I try to keep the rev range a bit higher and not roll about on the throttle too much accelerating in high gears. 3. The colour of the smoke was blue, which I guess tracks. 4. The spark plugs used were NGK D8EA, the plug caps were the NGK ones DSS sells. 5. Timing was configured with the help of this video https://www.youtube.com/watch?v=3933ouJ1wrI and I used a timing light. (this isn't to say that I didn't make a mistake of some sort, of course.) 6. I didn't adjust the mixture dependant on the altitude I was at. I can't say I was being that observant about the altitude. a quick google suggests the highest I got was probably about 900m elevation.
4
« on: October 31, 2024, 12:36:15 PM »
Hi All,
Took my CB400F for a trip along the Pyrenees, Bilbao to Barcelona but unfortunately fully complete the return trip.
The route I took meant the bike covered approx 750mi with a mixture of 30mph and 80mph roads - some riding was enthusiastic and some riding was cruising. The fuel I used was whatever standard e10 fuel as "super" wasn't always available.
At some point, the bike began overheating, smoking, had an unstable idle and would not accelerate past 60mph prompting me to cease riding for the remainder of the trip through fear of damage.
The bike was rebuilt some years ago using a mix of OEM/pattern parts (in particular the rings were aftermarket) and has covered approx 12000 miles.
Bike is back home and currently (slowly) in the rebuild process.
On dissassembly, there appears to be some minor damage to the pistons, rings, bores and head. (see the pictures attached). It appears to be localised to cylinders 2 and 3, cylinders 1 and 4 are visually ok and have good compression.
1. Any ideas on what could have happened or some ideas on what might have caused this situation? it would be pointless to rebuild and ignore this as it could happen again.
2. Are any of these components savlageable? The cylinders are actually smooth, can't feel anything by fingernail but there are a couple of dents. Probably due to the piston rings breaking up. Perhaps a rebore to 0.50 and use the DSS aftermarket piston/ring kit again?
As for the head, it does not look like theres damage (on initial look over) to the valves, valve seats or sealing faces - could this damage be removed with a rotary tool and tidied up? or is a replacement head necessary?
3. other misc information
- Engine oil used halfords petrol/diesel oils with a higher zinc content changed at 1200mi intervals.
- So far, it does not appear that theres been oil starvation. It looks like the head has been recieving plenty of oil but further inspection of the pump etc still needs to be done.
- Carbs have genuine jets and parts, no obvious signs of blockages etc.
- Genuine points ignition which appears to be adjusted correctly (via strobe light) and is functioning.
5
« on: December 20, 2017, 12:29:07 PM »
What taysidedragon said.
Good technical content. Thanks for Posting. I'm sure it will have a subconscious affect on the way I ride my 400 from now.
6
« on: December 19, 2017, 03:43:35 PM »
Just to confirm what already has been, I recently stripped my forks down for anodising and my new fork oil seals had a spring on both sides of the seal (CB400F). I installed mine the same orientation as Julie has done. on the first page.
7
« on: September 21, 2017, 04:42:21 PM »
Thanks Ian,
How did you remove them, with heat, penetrating oil and the ol' double nut technique?
8
« on: September 21, 2017, 02:34:13 PM »
Hi,
I'm toying with the idea of anodising the aluminium fork lowers on my cb400f.
Is it possible to safely remove the Studs on the bottom and the one on the side? Are these press fit or threaded?
Thanks
9
« on: September 21, 2017, 02:29:17 PM »
No, Unfortunately my bike didn't come with one when I bought it 
10
« on: September 20, 2017, 05:55:43 PM »
Sorry to bring up this thread,
To close this thread out, I couldn't seem to find what I was after, so I ordered the chain and sprocket set from David Silver Spares and it fits fine.
Thanks
11
« on: September 02, 2017, 11:23:53 AM »
Ok, I'll send this kit back then and let wemoto know that this kit doesn't fit the cb400f as advertised.
I'll grab the sprockets from dss,.
As for the chain, my preference would be to have a coloured chain such as bright or gold finish rather than the self coloured one dss sells. Does anyone have any recommendations?
12
« on: September 02, 2017, 08:26:22 AM »
Hello Ladies and Gents, I am in the process of replacing my Drive Chain and Sprockets on my CB400F. I purchased a Swift o ring / x ring chain and JT Front/Rear Sprockets in this Kit: http://www.wemoto.com/bikes/honda/cb_400_f_f1_400_4/75-77/picture/swift_heavy_duty_gold_sx-ring_chain_and_jt_sprocket_kit/Unfortunately I didn't get my bike with the rear sprocket chain guard but am I missing something here? The old Sprocket was flat on the outward face and had grooves on the inward face which the Sprocket Fastener bolt (Item 355) seemed to sit in and the new JT Sprocket is just flat allowing the Sprocket Fasteners to spin This can been seen in the attached picture comparing the two. Secondly, on the new Sprocket there is a lip which interferes with the flanged nut. Reversing the Sprocket doesn't let it sit any better against the Sprocket Fastener bolts. Regarding the chain, The new chain measures ~25mm width at the pins, the old chain measures ~22mm. Being a wider chain slightly, it appears to be catching on the engine casing, is this expected or normal or is there some sort of adjustment here? would neatly filing the case back on the catch points cause any issues? (See attached) Thanks.
13
« on: March 14, 2017, 06:24:00 PM »
Hi chris,
That sounds good to me. Thanks for taking that measurement.
Regards, Ryan
14
« on: March 14, 2017, 11:05:13 AM »
Hello Good People,
Regarding the CB400F,
Does anyone know or could anyone measure the height of the tool tray lid?
Thanks
15
« on: January 07, 2017, 09:33:16 AM »
I don't know, I think there will always be a market for things like this. People are always drawn in by the fasions and relics of years gone. I'm 25 now, owned my 400f for 2 and a half years I guess and I wanted a 400 for a further few years before that, got swizzed for this one, what i was told was meant to be a light resto turned into replace anything engine related. It's my second bike after my honda xl varadero 125. I wanted this bike as soon as I watched this video of a 350f for some reason: https://www.youtube.com/watch?v=emjPQhb8-ncObviously not because of nostalgia and noone in my family rides bikes other than my grandfather but he gave it all up before I was born. I just loved the look and I wanted to have something I could work on, It's been a pain and I've wanted to watch it burn a few times like anyone with a project but I love riding it, the sound, the smell and I love the look of it (I do wish it was a bit more powerful though...). plenty of my friends like it too and we have apprentices at work that are 16/17 and love it also despite there being lots of newer, nice, bigger and faster bikes in the parking area. A friend of mine younger than me, his first "car" was a Land rover series IIa back when he turned 17. I don't know where he drew his inspiration for that, But it's pretty cool. I guess my point is that fads come and go certainly but I can't see the market for old classic bikes such as the ones on this forum will crashing to the point of worthlessness. I've come to terms with the fact it's not worth anywhere near as much as I've spent.
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