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

[Seabeowner]

Very interesting to see the 400 in so much detail. Thanks for posting. And interesting it's completely different to the 500/550, where not only are the restrictors at the base, but oil is fed to under the camshaft surfaces only and the cam faces are dipped in a bath. Honda either had teams working in pretty much isolation or they were doing a lot of experimentation and we were the guinea pigs.

[hairygit]

My feeling is that the 400/4 was a later idea/development than the 750/500/550 fours, and experience from the earlier motors led the the cam spraying idea. Done from the design stage they probably hoped it would reduce problems and warranty claims and improve reliability. It would have been prohibitively expensive and disruptive to modify the heads of the earlier models in this way. Just my take on it.

[Johnwebley]

My feeling is that the 400/4 was a later idea/development than the 750/500/550 fours, and experience from the earlier motors led the the cam spraying idea. Done from the design stage they probably hoped it would reduce problems and warranty claims and improve reliability. It would have been prohibitively expensive and disruptive to modify the heads of the earlier models in this way. Just my take on it.

 I like the 500 cam lubrication,with pressure feed to the journels and oil dip/bath for the lobes and followers ,how does the spray
 work better ?
BUT. very interesting ,love these threads

[hairygit]

The 500/550 oil bath works okay, but when the cam is turning at 4000+ rpm at high engine  speeds, centrifugal force will obviously decrease the amount of oil that can cling to the cam lobes compared to a constant spray like the 400 gets, as I said, just my take on Honda's thinking at the time. After all, the 400 system would increase production costs per unit, so they obviously thought it was worth the cost.

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[Laverda Dave]

John,
There is an oil bath of sorts in the 400 head directly below the camshaft. From memory I think only the cam lobes themselves dip into the oil in the bath as the cam spins.
As the oil sprays out of the drillings from the spray bar over the cam it collects in the oil bath to a certain level. When the level is reached the oil runs back down into the engine. Maybe Julie has a photo of the top of the cylinder head to demonstrate the theory?

[Laverda Dave]

Here's a photo of the cylinder head from my engine. The 'oil bath's sit between the cam bearings either side of the cam chain tunnel.

[Nurse Julie]

Here's a photo of the cylinder head from my engine. The 'oil bath's sit between the cam bearings either side of the cam chain tunnel.

Same pic as I would have posted but, such a glorious day here, i have been out for a lovely long, fast ride, looooooovely 😊😊😊

[Bryanj]

I do hope you were not exceeding the speed limit Julie! As a truck driver VOSA have just decided that they can do us for "Historic" offences up to a month old from a tachograph printout

[Nurse Julie]

I do hope you were not exceeding the speed limit Julie! As a truck driver VOSA have just decided that they can do us for "Historic" offences up to a month old from a tachograph printout

Moi, break the speed limit Bryan, never  I only ever ride as fast as the road conditions and traffic volume allow. Today, the road conditions were perfect and there was no traffic on the roads.....the perfect combination to blow the cobwebs out 

[Johnwebley]

I do hope you were not exceeding the speed limit Julie! As a truck driver VOSA have just decided that they can do us for "Historic" offences up to a month old from a tachograph printout

Moi, break the speed limit Bryan, never  I only ever ride as fast as the road conditions and traffic volume allow. Today, the road conditions were perfect and there was no traffic on the roads.....the perfect combination to blow the cobwebs out 

   I agree,been perfect here,and a nice blast at just over 7,000 rpm for about 4 miles cleared the pipes,cobwebs and me out !!!

 mid october and still warm and sunny !! long may it continue !!

[Woodside]

me too took my old fireblade for an mot this morning...les than a mile from my house just got in and ive clocked up 110 miles....i have been thinking of selling it now im thinking perhaps not

[Nurse Julie]

me too took my old fireblade for an mot this morning...les than a mile from my house just got in and ive clocked up 110 miles....

So you were out for just over 5 minutes then Jason 

[Woodside]

hhmm awol 3 hours
almost ended up in brighton

[Nurse Julie]

John,
There is an oil bath of sorts in the 400 head directly below the camshaft. From memory I think only the cam lobes themselves dip into the oil in the bath as the cam spins.
As the oil sprays out of the drillings from the spray bar over the cam it collects in the oil bath to a certain level. When the level is reached the oil runs back down into the engine. Maybe Julie has a photo of the top of the cylinder head to demonstrate the theory?

I have just put the camshaft back in place to see if I can get any further insight into this. It was impossible to photograph the underside of the lobes in their 'fully down' position and impossible to measure also. To me it looks like there is about 10mm clearance under the lobe to the bottom of the 'bath'. What I did see though is a definite 'tide mark' around the edge of the bath which would suggest that what Laverda120 says is correct, that the cam lobes dip in the oil bath on each revolution and possibly the tip of some of the lobes may sit in oil when the engine is not running (obviously depending on where the cam stops) . What I can't find though is any drain holes out of the baths, so where would the excess oil that is sprayed from the oil arms go when the bath is full?.

Tide mark
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And again
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[hairygit]

Most of it goes down the camchain tunnel.

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