Author Topic: What else to do when resealing top end?  (Read 819 times)

0 Members and 1 Guest are viewing this topic.

Offline ReedNTX

  • Full Member
  • *
  • Posts: 10
What else to do when resealing top end?
« on: April 03, 2018, 06:09:48 PM »
Getting ready to do a reseal on the top end following the "leak free top end" thread pending being able to get ahold of one of 754's weldless kits.

Will be doing a shift cover gasket, starter clutch rebuild, and oil pan gasket as well. Any other things you would recommend to do/check while things are apart? 

Bike is a 78 CB750F of unknown history, but with solid compression and oil pressure, and new looking valve train from what I could see with the valve cover partially off.

Offline HondaMan

  • Someone took this pic of me before I became a
  • Really Old Timer ...
  • *******
  • Posts: 14,019
  • ...not my choice, I was nicknamed...
    • Getting 'em Back on the Road
Re: What else to do when resealing top end?
« Reply #1 on: April 03, 2018, 07:05:50 PM »
Getting ready to do a reseal on the top end following the "leak free top end" thread pending being able to get ahold of one of 754's weldless kits.

Will be doing a shift cover gasket, starter clutch rebuild, and oil pan gasket as well. Any other things you would recommend to do/check while things are apart? 

Bike is a 78 CB750F of unknown history, but with solid compression and oil pressure, and new looking valve train from what I could see with the valve cover partially off.

Maybe get a set of new rubber "pucks" for underneath the cam bearings (rocker towers). You can get the right ones from PartsNmore. This is the #1 cause of oil leaks on these engines, due mostly to age and the years hardening them.

Did you also remove the head? If so, you will need a pair of 2.62x10.77 O-rings (Parker #111) to seal the 2 oil passages at the back of the cylinders, at the head. The standard 2.5x12 or 2.5x12 O-rings will not seal with today's head gaskets, because they are all thicker than OEM.
See SOHC4shop@gmail.com for info about the gadgets I make for these bikes.

The demons are repulsed when a man does good. Use that.
Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
Hondaman's creed: "Bikers are family. Treat them accordingly."

Link to Hondaman Ignition: http://forums.sohc4.net/index.php?topic=67543.0

Link to My CB750 Book: https://www.lulu.com/search?adult_audience_rating=00&page=1&pageSize=10&q=my+cb750+book

Link to website: www.SOHC4shop.com

Offline ReedNTX

  • Full Member
  • *
  • Posts: 10
Re: What else to do when resealing top end?
« Reply #2 on: April 03, 2018, 07:24:25 PM »
Getting ready to do a reseal on the top end following the "leak free top end" thread pending being able to get ahold of one of 754's weldless kits.

Will be doing a shift cover gasket, starter clutch rebuild, and oil pan gasket as well. Any other things you would recommend to do/check while things are apart? 

Bike is a 78 CB750F of unknown history, but with solid compression and oil pressure, and new looking valve train from what I could see with the valve cover partially off.

Maybe get a set of new rubber "pucks" for underneath the cam bearings (rocker towers). You can get the right ones from PartsNmore. This is the #1 cause of oil leaks on these engines, due mostly to age and the years hardening them.

Did you also remove the head? If so, you will need a pair of 2.62x10.77 O-rings (Parker #111) to seal the 2 oil passages at the back of the cylinders, at the head. The standard 2.5x12 or 2.5x12 O-rings will not seal with today's head gaskets, because they are all thicker than OEM.

Thanks for the quick reply. I have not yet taken it apart, as I am waiting to get my hands on a frame kit.

There is a steady drip that I believe to be a puck- it is coming from the fins just above cylinder 1 exhaust, and another that looks to be a head gasket coming from the left front corner of the head to cylinder mating area.

What is the correct thickness for the pucks? I remember reading that many folks were getting sets that were too thin.

I will have to double check the o ring measurements. I ordered a complete overhaul gasket set rather than ordering them piece by piece.