Best way to unseize my engine????

Hey fellas, just picked an 83 xj750 that has been sitting for the last 21 yrs and is in decent shape, accept the power plant is seized. The bike has less the 10k on it. Now What would be the best way to get her unstuck, rather that pulling it out and doing a complete tear down??? Any thoughts, suggestions or random cursing welcome !

C

 

First off, if it's really siezed, and you break it loose and run it, you could ruin pistons that would otherwise be salvageable in a tear-down.

But here-goes- - spray PB-Blaster , B-12 Chemtool , or Dextron tranny fluid , or Marvel mystery oil into the plug holes, let sit 1-2 days to penetrate rings, then put it in 5 TH gear, and push with a helper.
Pop the clutch a few times. If it's really bound up, the tire will just skid.

Engines can be had for about $200. A good rebuild that replaces guides and timing chain, and does everything the right way is about $800, with you doing all the labor, and errand running.

I hope you get lucky, and welcome to XJBikes !!!

 

Apparently, acetone mixed with atf outperformed many different types of commercially available penetrating oils. Never tried it myself, but I hear of good results with straight ATF, Marvel Mystery Oil or diesel oil left to soak. At least with ATF you know you won't bugger up the engine if it gets in the crankcase.

 

My friend and his nova can attest that WD40 is not the right solvent for this job.

 

For what it's worth, I recently aquirred a '77 XS750 that had been sitting for 27 years and was locked up as well. I was able to pull 2 of the plugs out but the 3rd (#2) broke off clean after working it back and forth using penetrating oil on it. I had popped out the ceramic center and shot PB into the cylinder as well as the other 2. Using the rear wheel in 5th gear I started to roll it forward and back a bit each day. 4th day it finally broke loose and I tore it down as I figured I could then get the cylinders off of the pistons. Problem was that half of the Valves had sat open and allowed moisture to get into the cylinder and on the valve, stem and seat. I was kinda of glad I didn't start it as it would have torn up the valve guides as badly rusted the valve stems were, not to mention the valve seats. I removed the valves, cleaned the head and lapped the valves. I was fortunate enough to get a full gasket set which had the valve seals in it which I'll replace. when I put it back together. I found the Rings were completely rusted to the cylinder and thats why it was locked up. I'll probably go ahead and replace the rings while I'm in there. I did get the broken plug out by working it from the cylinder side using my dremel and a drift punch. This bike only has 5433 miles on it, and for the $150 I paid for it, I figure it's worthy of a rebuild.

 

Also remember that all rubber parts internal to the engine are now over 25 years old, which is reason enough to do a complete rebuild as they would probably leak and provide unsatisfactory sealing.

 

21 years, you may not have any rings left in there
so many things in there could be rusted you would have a better chance of hitting the lottery

 

Welcome Greaser!
As you have heard from the choir, you would be better served pulling the engine and going through it. A used engine would be an excellent idea. That will give you time to go through said engine and take care of it properly. Best of luck in your efforts.

 

At the risk of being shot, I can tell you that the engine on my 900 Seca was seized when I bought it. I broke it free by rolling down a parking garage incline and dumping the clutch in first gear. I then proceeded to run the bike for about 3 weeks with the old oil in it. When it was drained, it came out looking like hot chocolate. LOTS of rust. Having said that, no other signs of wear ever manifested themselves in the following 2 years of ownership, which included many miles of WOT 130mph riding. I don't recommend it, but sometimes you get lucky.

 

MacMcMacmac :
i hear ya, but 21 years, thats a long time do you have any idea how long yours sat idle ? just curious
i wonder how long it takes one to seize up?

 

I finally got the cylinders off of the XS750 and 2 of the 3 pistons had broken rings. If I had ran it like that I'm sure I would be looking for more than a set of rings and a full gasket set...

 

Twenty-one years is way too long to expect not to have some Cylinder and Valve issues.
But, those 21-years were unkind to other parts and systems; too.

You shouldn't be thinking about getting this bike on-the-road anytime soon.
You've got a shopping list of things to do before the bike would be in any condition to ride ... I am quite sure.

I've seen ruined headset bearings after two years of sitting.
Brakes.
Cleaning-up and cleaning-out after creatures and insects.
Seals.
Did I mention Seals?

Sometimes you get very lucky and a sit-a-rounder just needs the Carbs pulled and cleaned.
Other times you aren't so blessed and every fastener you undo snaps-off and you get behind the Eight Ball ... in a hurry.

If the Bike is "Clean enough" ... you might consider a Cardiac Transplant.
Put a used Engine in it and take your own sweet time looking into rebuilding the one that seized.

However this works-out ... Good Luck and welcome to where we'll be to offer you a Tool to borrow or a shoulder to cry on.
Hopefully, this adventure will have a happy ending.

Welcome to XJ-Bikes.
I hope we're talking tuning some day.
Right now, we're talking restoration.

A long and winding path a few of us, in here, know ... by heart!

Ah hopes yeh gots yer Mo-Jo woikin' ... 'cuz you be needin' id 'bout now!

 

Hey fellas, took your advice and pulled the engine out and tore her down. Found that number 1 and 2 pistons seized solid in the bores. So now i'm gonna look for a used motor (cheap hopefully) and drop her in. I tried to beat the pistons out of the cylinders, but they're stuck incredibly well. I had a 5lb sledge and a 2x4 and they would not budge, they were even soaking of the past few days in a mixture ATF, diesel, and some sort of super penetrator. Oh well, how much more work it to get the crank out? Do I have to split the case?
I'm new to bikes, my forte is diesel....
Thanks for the help.

 

That bike had sat in an unheated garage for 13 years.

 

There is a product called Mouse Milk that will eat rings and not harm the aluminum pistons. http://www.mousemilk.com/

 

OKay, pulled the case apart today for inspection. All the rings on number one and fused into the piston, gonna try to let em soak in atf over the next few days to see if they free up, but most likely gonna need a new set. Amazingly after 21 yrs of sitting, the internals are in immaculate condition. No signs of wear on anything ( not kidding ). Although I need to get a timing chain, Had to cut to remove head, but other than that, all i have to do is clean the crap out of the carbs And I can begin reassembly, (after I get a manual for torque pecs).Oh I should probably inspect the oil pump to eh?

 

would you have been able to take the chain loose if you would have taken the sprockets and cams loose. then worked the chain around to get to the chain link?