Topic: Advice about a seized engine.

[Hotwheelbill]

So, my 1972 CB750 is still seized. I have pumped fork oil, transmission fluid, diesel fuel, and much Aero Kroil into the spark plug holes. I tried to rock it with the points nut and broke off a tooth on that washer. I have tried the kick-start and have put more that I am comfortable with pressure on it. What other leverage points can I use? There is no chain on the bike Right now.

[DV Red Herring]

How long has it been soaking?

[ekpent]

 Pull the alternator cover off the left and use a breaker bar on the bolt head in there inside the rotor..

[Stev-o]

Pull the alternator cover off the left and use a breaker bar on the bolt head in there inside the rotor..

+1 try turning the crank on the stator end, never the points side.

Even better is to rock the entire bike while in third gear with the plugs out.

Can make a nice shooter when she frees, I have the record - 17'!

[Hotwheelbill]

How long has it been soaking?

One day.

[Hotwheelbill]

Will do. Thanks for the advice. I have no choice but to let it sit a few days as I will not be able to be back at it until later in the week.

[MikeSimon]

Why would you want to "unlock" a seized motor without taking it out of the bike and remove the head? You will have to look at the cylinders and rework them anyway. If a piece of ring brakes off and you fire the engine, you do more damage.

[DV Red Herring]

Acetone and Trans Fluid is a better concoction. It may well take more than a few days to get it to unlock, especially if you can’t get a lot of fluid into the motor.

I had a motor that I literally soaked on and off for 6 months and never got it to unlock. Had to pull the head and BBQ the pistons, AND STILL use a breaker bar.

That's one way to get them hot!!!

[Stev-o]

Why would you want to "unlock" a seized motor..

A "stuck" motor is typically the rings rusted to the cylinder. It will be a lot easier to remove the cylinders if the motor is freed up.

Trust me, I've been there.  A stuck cylinder can be a real bear to get off without damage.

[seanbarney41]

Why would you want to "unlock" a seized motor..

A "stuck" motor is typically the rings rusted to the cylinder. It will be a lot easier to remove the cylinders if the motor is freed up.

Trust me, I've been there.  A stuck cylinder can be a real bear to get off without damage.

not to mention that it's surprisingly common for these engines to run fine after getting the rings freed up

[Cormz02]

Marvels mystery oil worked for me, I let it soak maybe 4 hrs and then slowly worked it and it came free.


Sent from my iPhone using Tapatalk

[Terry in Australia]

Why would you want to "unlock" a seized motor..

A "stuck" motor is typically the rings rusted to the cylinder. It will be a lot easier to remove the cylinders if the motor is freed up.

Trust me, I've been there.  A stuck cylinder can be a real bear to get off without damage.

not to mention that it's surprisingly common for these engines to run fine after getting the rings freed up

Yep, the F engine I initially used in my K2 "Bitsa" came out of a Seeley that sat for many years, and was locked up when the new owner bought it, and from what I'm told it took a lot of effort to un-stick, but runs fine now. Don't pull them apart unless it's absolutely necessary!

[carnivorous chicken]

not to mention that it's surprisingly common for these engines to run fine after getting the rings freed up

I'll third that...

[setdog]

How long has it been soaking?

One day.

Unless youre in a hurry, just let them soak for several more days at a minimum.  Maybe even until next weekend. 

I would just try bumping it every few days. 

whatever you do, DO NOT be hasty, heard many stories of people bumping the rings free and then not having to rebuild

so please, take your time. 

[754]

It depends what you want to do with it.
 If you are parting it out, you may want to sel, it in one lump.
 I think that one had bad fins on the head.

[Yamahawk]

Acetone and Trans Fluid is a better concoction. It may well take more than a few days to get it to unlock, especially if you can’t get a lot of fluid into the motor.

I had a motor that I literally soaked on and off for 6 months and never got it to unlock. Had to pull the head and BBQ the pistons, AND STILL use a breaker bar.

...looks like a hot spot to bbq a filet mignon wrapped in bacon... and the drippings might act like a penetrating oil! Yeah... that's it... penetrating oil.
Charlie

[gwallis]

Marinade in Marvel's Miracle Oil for several days... preferably with some kind of Hot Plate under the engine... then rock back and forth in 2nd or 3rd gear.

That's what has worked for me in the past.

[b52bombardier1]

Use some 1000 watt heat gun heat or a propane torch kept moving around the heads to speed things up a little.

But never be in a hurry. Let the chemistry and heat work for you.

Rick

Sent from my SAMSUNG-SM-N900A using Tapatalk

[ekpent]

+1 on the heat. Can't hurt and might get a little metal moving around and better seepage. Did the heat gun on a 350 Kaw Triple along with some soak and believe it helped. Ports on a two stroke make it hard to 'fill' the cylinder depending on where the piston is situated.
  Its pretty much dependent on how a bike was stored if a seized engine will live again. All tucked away in a nice dry pole barn or garage good chance maybe. Stored outside in the elements for a long time with open carbs etc--good luck but probably should come apart. Another cause for a seize could be a torn up top end. An oil drain or sump pan inspection for debri can give those clues as well as seeing if water is in there.

[PeWe]

Engine stucked after years of mo care. Give the chemicsls a week to penetrate. Heat the cylinder block witj a heat gun until you’ll smell burnt oil, an hour or more. Too much physical force will harm the engine.

[Duke McDukiedook]

Acetone and Trans Fluid is a better concoction. It may well take more than a few days to get it to unlock, especially if you can’t get a lot of fluid into the motor.

I had a motor that I literally soaked on and off for 6 months and never got it to unlock. Had to pull the head and BBQ the pistons, AND STILL use a breaker bar.

50/50 blend to be exact. Don't try and hurry the results too much or you might break more than what was already broken.

[Don R]

 I have a 10,000 mile engine that had 10 oil changes then left in a barn for years with the carbs off. I had a strap wrench on the rotor and a ratchet strap holding tension on it while heating it lol. It's still stuck, the cylinders that had open valves were full of rodent waste. When I decide I have time to clean it up I'll split the cases, hopefully the trans and bottom end are OK.
  I have another one that was leaned against a clothes line pole for years outside with no carbs, the ports were stuffed with shopping bags and it was as clean as a whistle inside. You never know. I hope yours is like this one.

[Hotwheelbill]

Pull the alternator cover off the left and use a breaker bar on the bolt head in there inside the rotor..

So, I got around to that today and turning it counter clockwise like I should only loosened the bolt. Put some arm on it in the clockwise but just really tightened the bolt......Don't want to break anything.