Author Topic: CB400F Engine Rebuild  (Read 14000 times)

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Offline jakec

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Re: CB400F Engine Rebuild
« Reply #100 on: June 10, 2020, 11:39:33 AM »


Engine has been sitting in the bike for 2 months while I waited for piston rings. I got the rings last week and i plan to install the cylinder on the engine after work today. Can anyone with experience confirm assembly?

In between case & cylinder:

1x Base gasket
2x large dowel
4x cylinder sleeve O ring

In between cylinder & head:

1x head gasket
2x oil jet with O ring
2x large dowel with O ring
2x large dowel

Nothing goes in the non-circular holes at the front corners? What is the point of the oil holes there? It seems like there is not corresponding hole on the underside of the head.
1970 CB750 K0
1977 CB750 Chop
1997 XR650L

Offline bryanj

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Re: CB400F Engine Rebuild
« Reply #101 on: June 10, 2020, 10:50:23 PM »
Should be O rings in the base where oil feeds up
Semi Geriatric ex-Honda mechanic and MOT tester (UK version of annual inspection). Garage full of "projects" mostly 500/4 from pre 73 (no road tax in UK).

Remember "Its always in the last place you look" COURSE IT IS YOU STOP LOOKIN THEN!

Offline jakec

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Re: CB400F Engine Rebuild
« Reply #102 on: June 11, 2020, 10:02:41 AM »
So the two dowels at the base get O rings? Am I missing anything here? THank you
1970 CB750 K0
1977 CB750 Chop
1997 XR650L

Offline jakec

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Re: CB400F Engine Rebuild
« Reply #103 on: June 12, 2020, 09:53:49 AM »
Head bolts torqued last night and feeling really good about it. I was very careful to consult multiple videos, posts here, and the manual to be sure that I didn't miss anything.

Since I'm building the top end in the frame I thought about putting the pistons in the cylinder first then installing wrist pin clips afterward... but once I had it  mocked up in the frame it was too hard to get to the pins. So I took the pistons back out. But it was a good practice to see what it feels like to compress the rings. Strong taper on the sleeves meant it was pretty easy (at least on the bench).



Very very carefully (very streddful and sweaty) installed the cylinders on pistons. Successfully! I know there are two large dowels missing in the photo.



Here's where I'm at now. Cam shaft and guides are in. Waiting 24 hours to retorque head. Then I set cam timing and tensioner. Question about the tensioner - I couldn't see #$%* obviously since the engine is in the frame, but I inserted both into the channel and they both seemed to find their spot rather easily. The tensioner guide (rear) I'm certain went into the horse shoe because I could lift the horse shoe up and down by moving it. The front guide, I inserted and it seemed to go into its recess because now I can't pull it out.. haha. I did spin the engine and it seems to be in the right place relative to the chain.

1970 CB750 K0
1977 CB750 Chop
1997 XR650L

Offline minimo

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  • 1977 CB550F 1975 CB400F 1959 Ducati 200 Americano
Re: CB400F Engine Rebuild
« Reply #104 on: June 12, 2020, 09:55:23 AM »
Almost there. Looking fantastic!


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