CB400/4 ENGINE STRIP, ASSESSMENT AND REBUILD BY JULIE - NOW COMPLETE

[Nurse Julie]

LINK TO THE CB400/4 DETONATION THREAD
http://www.sohc.co.uk/index.php/topic,14609.msg122071/topicseen.html#new

OK, here goes

XMD650T.
A bit of history. 1978 ‘T’ Honda CB400/4 F2.  Name ‘ Hettie’. Owned by myself  for just over 3 years and ridden regularly. Clock shows 46,838 miles, I don’t know if this is genuine mileage or not. It looks like the engine has been apart before sometime in its life. I have done about 4,400 miles on her since purchase. She has been regularly serviced at about 1000 mile intervals. She had a leaky oil pump which was due to brittle ‘O’ rings, so new rubber parts fitted. Sump gasket changed twice as I originally thought it was the gasket leaking. Had a problem with rising revs when the engine was hot which has been resolved by fitting non resisted spark plugs in place of the resisted plugs Dave Silver says are correct for this bike.

Last year she had a rattle develop somewhere in the engine, to me it sounded at the top end possibly on the left side. The rattle only lasted a few miles and then disappeared and did not return all last year. This year, half way through this summer, the rattle returned, intermittently, both under load and de accelerating. The rattle stopped if I kept her under about 5,000 rpm but still very intermittent as she would go for weeks without any undue noises. As I have plenty of other bikes to ride I took her off the road at this point.

She has always burnt a bit of oil and smokes a small amount under load but no more than any other old bike and I have oil vapour blowing back into the air box.
Everything else on the engine sounds fine, no knocking noises or clunking and the clutch and gearbox are great. She starts first time, every time. I do not pussy foot around on this bike. I ride her quite hard and she performs really well for a CB400/4.

So, now to the plan.

Engine out, strip and assess and rebuild replacing any parts that need to be and having any machine work done that is necessary. Engine casings will go for acid stripping and then she will be prepared and repainted using Triggers tried and tested methods.
At the same time, I will be having the clocks refurbished with new clock faces and I need to drop the forks out and give them a good looking at as they bottom out and get ‘stuck’ sometimes.
I am aiming to do the strip, assessment and rebuild of the engine myself and Trigger will do any machine work that is needed but, I would like to do as much of it as I possibly can.

Hettie is now on the ramp and I will start unbolting the exhaust, carbs and ancillaries tomorrow. I plan to remove the top end whilst the engine is still in the frame and then lift the engine out. I will post updates and pictures as I progress. I will not be offended if no one comments throughout the process as I know for many of you, engine strip and rebuilds are old hat but, for me it’s the first time for doing a 4 cylinder engine. I have taken the top ends off my old Brit bikes in the past but that is the extent of my engine experience.




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[kevski]

I will watch this with interest, i have never stripped one of these tiddlers so it's also a first for me, think it will be a few years before my 350/4 will get this treatment as she only has 5 and 1/2 k miles on her, as for the rattle my Z1000 has an intermittent rattle but i know what it is, end float on the cams quite a frequent problem on gs's as well, so plenty of pictures please.

[Johnwebley]

I shall enjoy this thread,

  always willing to learn from the experts

[Laverda Dave]

Good luck with the rebuild Julie. If you need a new cam or the rockers redressed I can recommend Newman Cams.
Don't touch the carbs!!! 

[hondarc166]

I will watch with interests and learn more

[Rozabikes Tim]

Think we are all watching this one! No pressure then Julie.  Best of British  (or is that Japanese)

[Nurse Julie]

Thanks Tim and everyone else............now, where is the BIG hammer 

[kevski]

 

[Nurse Julie]

Found this one!! Oops, 2 by the looks of it 

[mike the bike]

I hope you don't think it was me that made off with your sidepanel.

[Nurse Julie]

I hope you don't think it was me that made off with your sidepanel.

No Mike, I know it wasn't you ( although I saw you eyeing it up). I have the panel off because I have nicked the battery temporarily for my CB550 project 

[Orcade-Ian]

Having just about finished my engine, I'll watch with great interest. They really are lovely little units - built like a Swiss watch.  Agreed, there are some bits which cause headaches but nothing compared with this single cylinder Norton which occupied my bench for far too long.  Still not quite finished but I'd had enough and wanted to do some interesting stuff. Don't know what you intend doing about the cam chain horseshoe but if it's buggered like most, I'll gladly make you a new pivot pin and dress the marks out - unless that's what Trig would do anyway.
I also strip the head and barrels off in the frame and build up the same way - it's much more manageable that way and everything added on is on a solid platform.

Ian

[Nurse Julie]

Thanks Ian.
I had given thought to the horseshoe and luckily a very good original genuine one was available to me and another very kind forum member gave me some really good 2nd hand blades.

[hairygit]

Just a thought here, but everyone moans that Dave Silver recommends incorrect spark plugs. But, when these old Hondas were new, they had those dreadful metal shrouded plug caps, which to me suggest it was some kind of shielding for electrical interference. I've never tested the resistance of one of the original plug caps, but there is every possibility that they had far lower resistance than the NGK resistor caps that are available today, which would explain the recommendation of resistor plugs, but obviously with the modern caps there is an issue with resisted plugs as well. I know a couple of members have some of the old style shrouded caps, how about measuring the resistance of them? (Ash?)

Sent from my X6pro using Tapatalk

[Nurse Julie]

Agree 100% with what your saying about the old metal caps  Hairy but Mr.DS advertises resisted plug caps and resisted plugs for the CB400/4.