Seven Fifty cafe-racer. Engine assembling, part 4.

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Engine looked mostly assembled but in fact there were still a lot of parts to install.  Like oil system pipes.

Or Seven Fifty OEM exhaust studs.

Luckily, 7mm nuts were available in one of shops on local car parts market.

Then I installed last routine parts like 20mm sealing bolts or intake manifolds.

And then was time for more interesting work.  Honda CBX750 valves are larger than CB750 Seven Fifty  valves but both engines equipped with the same hydraulic tappets. And these tappets need to be checked and cleaned. The procedure itself is simple: you just put hydraulic tappet in can with clean kerosene and pump it until no sign of mud  left. You also must check that tappet work is smooth and after it’s free play after procedure it is in a service limit. The only minor obstacle is that you need special bleeder for that.

But, as I found out, it  might be replaced by 1.8mm drill bit. You have to insert blunt end into the hole in the top of hydraulic tappet and then, without any force applying, feel the deepening inside of tappet and put the end into it.  After that hydraulic tappet could be pumped with bare hand.

 I checked all tappets and cleaned them. I changed kerosene continuously and pumped all tappets three times until reached satisfactory result.

 So it was time to put all cylinder head’ insides back on their places and to align camshafts. Sounds easy if don’t mention large quantity of parts. Here is so called exploded view of parts I had to assemble and install:

I had to do everything properly and it was around midnight when I finished, so I had no time for photo shooting. The only exception was this photo of new dowel pins for camshaft holders.

So here is view of all components installed and camshafts properly aligned:

And a couple of assembled engine photos. I’ll install  electrical components later, as well as covers, after I’ll polish them.

Looks like the end of engine assembling story. Didn’t I forget something? Oh yes, there was the last task. I had to shove together and  remove huge pile of parts packages:-)

The end.

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  1. Youri de Vor


    I’ve scrolled through your posts and I haven’t been able to find which pistons and rods you used. I saw some info about the pistons but nothing about the rods other than they came from ebay.
    Could you please share which you used?

    1. gazzz (Post author)


      I used 70mm pistons from Honda VFR750 RC36 and connecting rods from Honda CB700 Nighthawk 1984-1986.

      Kind regards,

  2. Dave

    Outstanding blog and build gaz!!!

    Am I correct in saying a CBX750 head will fit the CB750 engine with no problems? Would this result alone in the extra hp gain between them… 75hp to 93hp?


    1. gazzz (Post author)

      Thank you!

      Difference between CBX750 and CB750 engines is not only in cylinder head but also in camshafts. And yes, the CBX750 head will fit the CB750 engine. I used a CBX750 cylinder head, camshafts and ignition system (along with all wiring) in my CBX/CB mix. Also, CBX750 exhaust header pipes have larger inner diameter than those from cb750. It’s also a significant difference.

      Kind regards,

      1. Dave

        That’s great! Do you have to have the CBX750 exhaust header to fit the CBX750 head? Or will the CB750 headers work it just that they are smaller inner diameter?

        Is the ignition system different too?

        Thanks for your help! Much appreciated

        1. gazzz (Post author)

          I run a modified  free flow aftermarket CB750  exhaust header  (ceramic coated).

          Ignition system is different, however ignition coils are interchangeable.


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