Honda CB400F2 Restoration Part Five
Series originally printed in Mechanics in 1994

Getting It Back Together

I had one final go at cleaning the crankcase halves, then went through all the threaded holes with greased 6 and 8mm taps to clear blasting residue from the threads. The cam chain tensioner had been attacked at its pivot by the chain, so I relieved the damage with needle files until it operated smoothly. The plunger was also a little stiff, so it and its bore were deburred and polished.

The cylinder head and rocker cover came in for the same clean up, prior to assembly. The valves were fitted with new springs and went back in with minimal swearing. I hate jiggling all those little collets into place. Before it was too late, I noticed that I'd put two of the rockers in back to front, so that the cam follower pads were poking out of the inspection caps.

Having run out of little jobs to defer the final big moment, it was time to start putting the engine back together.

The top crankcase was laid upside-down on the bench, and all of the innards dropped uneventfully into place. OK, I did have one thrust washer left over, but a scan through the Honda parts book located where the little blighter had escaped from. Of course, when I pulled off the appropriate caged needle roller, it jumped out of my hand into a dusty corner. With the bearing cleaned and re-oiled it all went back together.

With the crankcases torqued down, I pondered the problem of getting four sets of piston rings into the barrel. I tried using a set of Jubilee clips as ring compressors, but they got in the way. Fortunately, the pistons are tiny compared with the space between them, leaving plenty of finger room. By rocking the cylinder, I was able to get the two outside pistons in their bores one by one. The middle two pistons were then eased into the generous lead-in at the bottom of each bore by rotating the crank with one hand as the pistons were guided in with the other. The whole job was over in about 3 minutes, leaving me wondering what all the fuss was about. Special tools? Bah, who needs em!

Assembly came to a halt when I found that I had forgotten to put two of the crankcase bolts in. Guess what? They have to go in before the barrel is lowered. With a little experimentation, I found that I could raise the block just enough to jiggle the bolts into place.

With gaskets in place, the head was lowered on and torqued down. Once the cam chain tensioner blades were in place, I slackened the tensioner clamp bolt. The rear blade shot up like a Jack in the box, so I am fairly confident that it will do its job.

During the warm weather, work continued on the petrol tank. Yellow is an unfortunate colour for outdoor spraying as it attracts all manner of insects. I got tired of rubbing down trapped bugs, so the finishing coat of yellow was applied on a damp morning before they had woken up! The paint was left to harden for several weeks before masking up for the stripes. If the paint isn't hardened, masking tape will mark the surface. I used 3M fine lining tape to mask up, and small touch-up tins to paint in the stripes. The finish on the wider stripe is not brilliant but looks OK from a distance. Spraying would have given a better finish, but the extra masking up is such a palaver. With the stripes done, the tank was finished off with a set of fifteen year old transfers bought from John Skellern, and several coats of clear lacquer.

The front brake calliper was seized solid, but I managed to persuade the piston out with heat and judicious blows with a copper hammer. The bleed nipple snapped off when I tried to undo it. While I managed to drill it out, the taper seating got damaged in the process. I bought another calliper for £15 and gave it a good roasting with my butane torch before attempting to remove the nipple. This time some of the aluminium thread came out with the corroded nipple. Not to be outdone, I cleaned up the thread with an M7 tap and made myself a slightly oversize nipple from a piece of stainless. It took most of a rainy Saturday with Father in Law's lathe and milling machine, but I was happy that I had saved the ú75 for a new calliper. I already have a new piston, so all it needs is a seal and a coat of satin black.

The front fork tubes were badly pitted. Regrinding and hard chroming would cost £75 + VAT, the pair, new tubes from David Silver, £40 + VAT each. I opted for a new set.

A couple of years ago, David Silver was selling complete CB400F wheels for about £35 each, so I treated myself. They were covered in dust & needed a good clean, but were indeed brand new. With a set of new Dunlops from Norman Storer, they were ready to roll.

For reuniting engine and frame I laid the motor on its side, then lowered the frame over it. This way there is less chance of knocking paint off the frame and only one pair of hands is needed. With the bolts in, the whole bike was lifted up to rest on the centre stand. The front end was propped up with the freshly assembled forks running in a set of taper roller head bearings. A shiny new front wheel and mudguard prevented the plot falling over. A set of Koni 'dial a ride' shocks at the rear completed the rolling chassis which I can now wheel around at will.

I am off on my holidays next week, but with all the dirty jobs out of the way it will be simply a matter of hanging all the remaining parts onto the frame. I shouldn't say this in case Bob gets excited, but the whole project will be finished for next month!

Graham Curtis 30th August 1998

Thanks to the following suppliers who helped with the project

Tippetts Motors (Surbiton) Ltd
312-320 Ewel Road,
Tolworth,
Surbiton
Surrey KT8 7AW

Mick Bull Motorcycles
Unit 2,
36 Canal Street
Derby DE1 2RJ
Tel 01332 367470

David Silver Spares
Unit 14,
Masterlord Ind Estate
Station Road
Leiston
Suffolk
IP16 4JD
Tel 01728 833020

Derby Plating Services Ltd
148 Abbey Street
Derby
DE22 3SS
Tel 01332 382408