CB750 froze up

[whataulooknat]

My cousin has an old 76 CB750 in his garage that hasn't ran since 1998. It ran when he parked it. The reason he quit riding it was the clutch was going out of it and he didn't have the money to replace it and lost interest. Well we decided to take it out and tinker with it the other day and we tried to kick it and the engine will not turn over at all. It is completely froze up from sitting. It was rained on multiple times before it was moved into the garage so I'm thinking thats what caused it. Any ideas if this bike could possibly run again? Where should we start?

 

[Bullit]

First thing you need to do, is take the spark plugs out and put some PBA Blaster in it or any penetrating fluid. Let it sit for a couple days and put it in second gear and try to bump it loose. Also take off the left side cover where your stator or alternator is and see if it is froze to the rotor. Drain the oil and look at it, metal in it, water and so on. Some people have used different things in the crankcase to loosen it up. I am assuming if it had oil in it, even old oil would be better than nothing. It is probably the rings rusted to the cylinders. So try the penetrating fluid first and see what it does.


Good luck and keep us advised.


Bullit

 

[whataulooknat]

Ok i'll keep you all up to date. The bike does have Oil in it still. Its pretty thick and old but it is oil at least. We haven't drained it and checked it for metal yet we just tried kicking it to see if the engine would still turn over. The bike did in fact run when it was parked though. It actually ran very well the clutch was just going out of it so he parked it.

 

[Curtis]

Drain the oil, add fresh, pull out all the plugs and just fill the holes with diesel fuel.

Let it sit for a few days - a week.

Take it to the top of a good sized hill, run with it, jump on, clutch in kick into second and dump the clutch quickly, it should free the motor with the quick snap

 

[whataulooknat]

the clutch is out on the bike

 

[Curtis]

Missing all together?

If not try and get some adjustment on it at the clutch actuator and then at the lever.

 

[whataulooknat]

no its not missing but it doesn't hold hardly at all that was the whole reason he quit riding the bike. I'll give it a try though. No harm in trying. Do you guys think that we could break it loose with the kickstarter after soaking the engine a few days if the clutch won't hold?

 

[surffly]

dont try and force everything....thats just a good way to damage things more then you started.

half acetone and half ATF is great. or marvel mystery.
let is sit for a week or so.

you can try using the kicker but if not take the covers off and turn right from the crank.
If you start running down hills and such you run the risk of breaking a ring or something.

honestly though if its been locked for 5+ years you are going to have to rebuild at the very least the top end so getting it turning over is really not alot of the battle to get the bike on the road