SOHC.co.uk Forums > Project Board
CB750F2 .... silk purse from a sows ear.
Spitfire:
I had a problem getting my F1 barrel off, one of the steel knock pins (corner one) had rusted and was holding the barrels to the crankcases together, it took quite a bit of gentle persuading to shift it without damaging the fins, maybe you are facing something similar, if you are certain that you have all the bolts out that is.
And Nurse Julie is correct that the original Honda head gaskets were extremely sticky and very hard to shift.
Cheers
Dennis
Trigger:
--- Quote from: SumpMagnet on August 15, 2018, 07:42:25 PM ---hell yes.... Julie mentioned it right at the start, and so far I have seen exactly why. The carb rubbers are like steel....the o-rings are brittle, the pucks had to be peeled off the carriers like old chewing gum off the sole of your shoe...
And that's just the top end.
I will be replacing every bit of rubber I possible can, as none of these items will ever seal, and would most likely crumble to dust. I do need to find a source of replacement rubbery bits though. Seen a few sets of 'engione rubbers' ... but no description of what's included. So will need to make a few phone calls before I unlock the credit card.
--- End quote ---
I have a large stock of engine Viton 0'rings, pucks, engine seals and so on. Send me a list of what you require and i will put some prices.
SumpMagnet:
Thanks Trigger 😀
So far, I have o my got halfway down .. but the list is:
8 tappet inspection o rings
6 pucks
4 small ovrings for the oil jets and the other 2 oil holes.
O ring on cam chain tensioner plunger shaft
That's so far .. the list will grow as I haven't reached the cam chain guides, guide wheels, crank oil seals, gearbox oil seals and suchlike
The cam chain tensioner rubber block is pretty rock hard, but I suspect that would mean replacing the whole shaft. The metal plate has very little wear though.
Dennis ...thanks for the tip. I have doused the areas I can with penetrating oil, and will let it sit for a day or two. I have undone all the bolts shown in the picture, so it is just gasket grip or something corroded in place. Could be time to start making some wooden wedges.....
SumpMagnet:
In the red corner........the CB750 lump.
In the blue corner ....... the ameteur mechanic.
After 2 falls and a submission....off with it's head was the cry! Yes....we got it done finally.
As always, these things have good and bad...so lets kick off with the bad.
1) I am not the first guy in here, and there was a little tell tale mark where someone had pried the head off before. Nothing serious...but of note for me.
2) The 4 bolts under the pucks were different. 2 were clearly replacements lacking the cast in washer and being fully threaded rather than a plain shank.
Now...the better stuff.....well...for me anyway!
The bores look really nice. No rust marks, no scoring and no discernable ridge at the top of the bore. I could see the horizontal hone marks but no evidence of vertical scoring or marks that looked anything like wear.
The o-rings around the studs were incredibly shot. One looked like a dead slug, and the others were crunchy. All will obviously want replacing. Going to need to clean out the muck around them too.
With the head on the bench,I did the old seal test.... pour a little fuel into each head..and see if it stays there. 2,3 and 4 were good as gold...but pot number 1 dribbled it's contents out through the exhaust valve. Not a surprise....I was told more than once on here that the exhaust valves were wear prone. The heads were pretty coked up, with quite a bit of carbon on the valves, but underneath things looked pretty good.
The barrels neweded a good clean from the oil I had dripped down there, mixed with some loose carbon...but once cleaned, things look nice. The pistons all look quite carboned up, but it all rubbed off pretty easily. Barrels off next, so I can check the piston skirts for wear. For now...I got some more oil soaking down the studs ready to lift the barrels tomorrow.
Trigger:
--- Quote from: SumpMagnet on August 16, 2018, 09:38:37 AM ---Thanks Trigger 😀
So far, I have o my got halfway down .. but the list is:
8 tappet inspection o rings
6 pucks
4 small ovrings for the oil jets and the other 2 oil holes.
O ring on cam chain tensioner plunger shaft
That's so far .. the list will grow as I haven't reached the cam chain guides, guide wheels, crank oil seals, gearbox oil seals and suchlike
The cam chain tensioner rubber block is pretty rock hard, but I suspect that would mean replacing the whole shaft. The metal plate has very little wear though.
Dennis ...thanks for the tip. I have doused the areas I can with penetrating oil, and will let it sit for a day or two. I have undone all the bolts shown in the picture, so it is just gasket grip or something corroded in place. Could be time to start making some wooden wedges.....
--- End quote ---
No O ring on "O ring on cam chain tensioner plunger shaft". There is a seal in the housing but, DO NOT disturb this as they were not a separate part ;)
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version