CB750 Crankcase jointing compound

[philward]

Hi Guys
Have just got all the bits for my xmas holiday engine build - verrrrrry expensive! Got the bigbore 836 kit from cruzimage Japan on ebay having done a bit of research on the SOHC forums - service was first class and arrived in a week!
New big ends, mains, bigbore kit, camchain, primary chain and all tensioners.
Its a few years since I've rebuilt an engine - CB1100RB and Phil Read Rep - so reasonably confident except it was about 20 years ago and was wondering what the current thoughts are on what jointing compound to use for upper/lower crankcases?
Also, can anyone recommend a company local to Wigan, Lancashire that can do the rebore for the bigbore kit and cost. I'm not too bothered about having it done quickly provided I get the bottom end completely built up over the xmas break, I'll be pleased.
Any help appreciated.
Thanks
Phil

[mick]

Hi Phil I use Hylomar Blue sparingly you don't want any getting into the oil ways  cheers Mick.

[LesterPiglet]

I've only ever used red Hermatite. Can you still get it?


YES

[philward]

Thanks for replies - I used to use Red Hermertite on previous rebuilds - didn't know its was still available - I'll check ebay. Thanks again

[Bryanj]

NO and a Thousand times NO to the red Hermatite!!! Its an oil way blocker as is Hylomar if too thick.

A VERY thin layer of silicone if you can't get Honda bond or Yamabond ( I think Dave Silver does the Honda one

[mick]

I thought I had put a very thin coating of sealant on when I rebuilt my engine and was surprised how much oozes out both inside and out when the cases are clamped shut  , so what ever you decide to use,  use it sparingly  cheers Mick.

[Bitsa (Ralph Wright - RIP)]

Hi Guys,
I have  been too lean on occasions especially around the extreme outer edges and only to find oil coming down from the crankcase bolts.
Cheers
Bitsa

[LesterPiglet]

I'm afaid I have something against silicone compounds. Too easy to apply too much. At least Hermatite does not solidify.

[fisjon]

Click the link below to see a photo of a CB650Z motor with Blue hylomar on the joints that I built up two years ago.
I put it on with a plastic shringe, placing a tiny bead on the outer edges of the casing, but as you see even a thin bead is probably too much. I looked inside the engine with a torch and could see a few small blobs and removed them, problem is you cant see inside the gearbox once it is sealed so it was crossed fingers after that. As far as I know the motor is still purring.

I think the cases are so well machined that just an even smudge will be enough to form a seal.

http://www.sohc.co.uk/index.php?topic=4964.msg25045#msg25045

[philward]

Thanks for all your replies - seems the key thing whatever I use is using sparingly particularly around oilways - but covering the whole surface.  Sent for some blue hylamar last night after first few posts as need it for time off between Christmas. Just read a bit about Hondabond and that's silicone based too so I'll have a go with the hylamar. I never worried before but being an old git now has turned me into a worrier! My only concern is how long it takes to go off whilst I'm fitting crankcase together - never had that problem with the red hermatite. Know what you mean about the red hermatite being associated with bodges - seen some of them back in the seventies - particularly on oily British bikes!
Thanks for all your help again guys.
Cant see the pics for the last post - must be my settings
Phil

[fisjon]

Humm! no picture, trying to work out why..............!!

Ok put a link in the above message to view photo of motor...sorted

[mick]

You will be ok with the Hylomar it gives you plenty of time to cover the joints and get the cases together  cheers Mick.

[ka-ja]

Hi,
     Never had any real problems with blue hylomar,I would say if it is good enough for Rolls Royce it is good enough for me, the one thing I did find some years on after a 400/4 engine strip was quite an amount of small droplets of it stuck on the oil pump suction screen, which again, reinforces previous advice on quantity used. As for going "off" during use, it should be allowed to dry a little before the halves are joined, but it is not a compound that "sets" hard, one of the reasons why its so good
Mick just beat me to it-----Ken

[Seamus]

Hondabond is recommended. Should be available from Dave Silver or even a Honda dealer. (maybe deamon tweeks or similar, but get grey/silver as it does not show)
If not then Threebond 1194 (in silver/grey) is an equivelent). This can be bought on Ebay