Topic: 1976 super sport cb750

[oldschoolrides]

Picked up a 1976 super sport 750 with an 836 but no proof of it. Well test road and it ran great. When to go on a longer ride on after all the paper work was handled and done.... Starts running like garbage and spewing oil on the left side of the head and out the tail pipe. So im guessing a head gasket let loose or and O ring. My question is how to do I identify if it does indeed have the 836 kit?  I would think I would need a head gasket for 836 if it also. Any thoughts or suggestions would be awesome. I do have a line on another motor for 100! Least thats a plus.

[ekpent]

Well obviously a tear down will tell you right away when engine is removed. Sometimes you can peek down a spark plug hole with a bright light and look for a domed piston if it has a 10.5 to 1 kit in it. I have a cheap snake scope for that kind of stuff. Correct head gasket should be used.

[oldschoolrides]

Well I took a an led pen and looked down throw the plug whole. It looks to domed pistons. I got the motor out last night. Rather easy with jack stands an bar trick, took 15 min.

The bike blew some pretty good smoke on rev and was smoking rather well from crank vent and leaking good from the head gasket. So Im going to tear it down an see what looks to be going on. Im new to diagnostics for oil burning problems. My thoughts are possible the head gasket aloud it, valve stem seals or rings? I imagine rings I would see some oil build up on the skirts? I plan on replacing the stem seals and lapping the valves.

I also wanted to say I have learned so much valuable information from this site. Thank you to everyone that shares there knowledge.

[oldschoolrides]

Also since this motor has been taken apart already should I replace the head studs? I've read they stretch over time an ti replace them with APE studs.

[goldarrow]

Also since this motor has been taken apart already should I replace the head studs? I've read they stretch over time an ti replace them with APE studs.

If this is your reasoning to replace parts, might as well replace the whole bike with 2015 models.....

[calj737]

It's never a bad idea to replace the studs with APEs and the nuts.

Here's a very good thread for you when reassembling the top end:
http://forums.sohc4.net/index.php?topic=107040.0

[oldschoolrides]

Well I tore into the motor today... what a mess.. Cam sprocket bolts were about to fall out being finger tight. Head bolts not tight... and I found some weird things on the lower jugs around the bolts with the orange rtv. looks like there is a rescues for an o ring but the sleeve are so big that wouldn't be possible. I checked another jug i have an there aren't any rescues like that. So im not sure whats thats about. The head gasket defiantly was leaking oil in pretty good. An found cam bearing chewed up. From what I've found on the net those look like 836 pistons. Lucky the bores look to be in great shape.

[Vinhead1957]

Is that a big gash in the cylinder wall too?

[Oldtech]

What the hell is going on with the valve pockets? Are those pistons in backwards?

[ekpent]

Is the cam stock or not. Look for an R number on it and if you see one probably stock. Looking at that cam cap the cam may be in trouble also. That orange goop can be an engine killer by blocking top end ports. Good thing you ripped into it, hopefully all is good with your higher compression pistons and sleeves though those pockets do look weird.

[oldschoolrides]

Man thats that what I thinking also. I've never seen them ground like that. The valves themselves show no evidence of collisions. Im thinking the other complete stock motor I got is going to be better off. The cam says Andrews with a K next to it and on the middle section EP-13 made in usa.

Seems like a briar got ahold of the motor... lucky me they didn't touch the rest of the bike... ha

[oldschoolrides]

Is that a big gash in the cylinder wall too?

I was a piece of RTV... Whoever put it together loved high temp and blue RTV ha.

[Vinhead1957]

Bad choice I wonder if it is the cause of oil starvation in the cam journals

[oldschoolrides]

Bad choice I wonder if it is the cause of oil starvation in the cam journals

I would have to agree that would have been the case. Even though most of the oil was leaking into the cylinder through the gasket ha... I cant imagine was the rest of the lower case an trans looks like.

[ekpent]

You can take the guess work out and remove your oil pan and see what is in/on there and also stuck to the oil filter screen 

[oldschoolrides]

You can take the guess work out and remove your oil pan and see what is in/on there and also stuck to the oil filter screen 

Haha right! Im sure it looks great. I will post pictures tonight when I open it up.

[750cafe]

What do the other cam bearings, caps and camshafts look like?      Those pistons must be installed backwards. 

Eric

[oldschoolrides]

What do the other cam bearings, caps and camshafts look like?      Those pistons must be installed backwards. 

Eric

Arrows are pointed to the exhaust they henry 900cc pistons. Im pretty sure the motor is a loss. The piston sleeves have alot scaring on the lower end of the bores.

[750cafe]

Where are you located? I could use a good titled frame.

Eric

[goldarrow]

I'm riding along with 750cafe, if you part out the bike I could use the wheels front and rear

[oldschoolrides]

I'm riding along with 750cafe, if you part out the bike I could use the wheels front and rear

I don't think im going to. The bike its self is in great shape!


More carnage.

[oldschoolrides]

Well I tore in the calipers last week also. Found my rear was seized up. Used the grease gun method to push out the pistons worked amazing! Then tried locating seals for the pistons rather expensive. But I had remembered my old 1990 volvo 240 i rebuild the rears with new seals and they were 38mm... well they are same as honda's. Bought four of rock auto for 10 bucks! Now I just need to figure out the size for the o-ring between the caliper halves for the rear. Anyone have a size? I know regular rubber won't hold up to brake fluid I need one made of EPDM material.

[Don R]

 It sounds like you will be fine. Looks like a nice bike and you're making good decisions.