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Discussion Starter · #1 ·
Thanks in advance for replies. I'm bringing back a T140 from the grave. It is seriously rusted. Inlet ports blocked from carbs blocked with white substance, aluminium corrosion I think.

Good news is, with heat and penetrating oil so far removed any nuts needed. Have partially stripped spark plug threads, but lucky to get them out.
However, now stuck. The pistons are seized, and cylinder head won't come off. Have raised cylinder block slightly, so crank isn't seized
I've removed all bolts and nuts on cylinder head except two central bolts that had extended hex nuts. Have banged head with mallet, heated with blow torch
Cylinder barrel filled with ATF and acetone, although didn't mix well. Heated barrels until atf is boiling. Wacker with mallet. Put in gear and ticked to and fro
Can't hit pistons directly because head on. Can't raise head using pistons because they are seized. What to do? ATF been in about two weeks
 

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Undo the two central cylinder head bolts to free the head from the cylinder.
 

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Hi Alex, Sounds like a tough case.
I know what you mean by not enough thread for 2 nuts.
There is stud remover that looked like deep socket with 3 roller bearings that grab stud. That might get enough grip.
There is also stud remover that is a threaded tapered collet that screws onto stud. Tapered sleeve squeezes tool to threads. Will unscrew it or break the stud.
You can buy what we call coupling nuts here. A hex nut about 3-4 times longer than normal nut. Screw it on 50%. Then screw hex bolt into top half. Tighten as much as you dare. Then turn both out using 1 or 2 wrenches. Whatever will work.
Similar to double nutting in concept.
Very well could be it can’t hold tight enough as double nuts sometimes can’t
There is huge difference in penetrating oils. Kroil is amazing. Liquid wrench is decent. PB Blaster is just ok. It could take 3 weeks to soak in. A tough case for sure with all you’ve done.
I always thought about a head puller that screwed into rocker box area.
Would probably bend the head, or pull the threads??

My ‘73 studs are stainless from factory. There’s a fair amount of exposed threads above cylinder. Gives corroding alloy a good grip. Good luck. I hope someone has better ideas than me.
Don
 

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No, not really any better ideas...I never had much success with any penetrating oil on seriously corroed parts as we see here in the northeast. Sometimes spent a lot of time on freeing up a vintage bike or auto engine to find it's beyond repair...
OP you gotta keep at it, oil and some real carefull prying and maybe the cylinder will break free...On WW2 aircraft piston engines grease is often pumped into the cylinders to free them...Real messy but if you alternate side to side you may get the head or cylinder to move..Of couse its all to easy to bend something...
 

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^ As in fitting a grease fitting to a bolt that threads into the spark plug threads ? Peter , (of course that'll only work if it's on compression)
I've had something similar for seized disc brake pistons .
 

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If all the head bolts are out except the two middle ones, try using a drift on them, hitting them sideways from all directions to break out any corrosion between them and the head.
If the engine is out if the frame you could try drilling them with a left hand drill bit. Centre drill first to locate the drill bit.
 

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Discussion Starter · #8 ·
Thanks for replies. Can't use grease gun, one valve snapped due to build up of the white corrosion-tapped it try and break some of it away.

I've accepted cylinder barrel needs replacing. The exhaust headers rusted through and debris is in the bores, feel rusted running screw driver down them.

Although badly rusted, there's a few surprises. Although little paint and chrome left, inside of tank is as new. The cylinder bolts I have taken out were not too difficult and without corrosion.

TRV7RVman-the hex bolt extractor sounds hopeful. Do you have a link to one?
1622011561332.jpg
 

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Often on an engine in that state, the main bearings will have rusted so strip it right down even if the crank does turn easily. I made that mistake once and left the main bearings. Started up to a lot of rumble and stripped it to find one ball had lost its surface coat. That bike will be an expensive build with all that rusted chromework.
 

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Discussion Starter · #11 ·
There's no gasket in the crankcases. Must have rotted away! So definitely have to take a look. My first project, so bitten off a lot.
I have/had another 3,000 mile T140, suffered catastrophic fire after backfire, so have most of chrome in mint condition
 

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I have always found Plus Gas to be a good releasing fluid. Old fashioned stuff, but it works well. Available in aerosol or cans. Worth a try before more dramatic methods are used.
 

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Discussion Starter · #14 ·
I've got a can of Plus Gas. Used it in the rusted nuts, although might be blow torch was most help.
But it's pricy, so was too stingy to pour it in cylinders. Being debris in them, would've needed a lot. Maybe time to lay bike on side, drain ATF, flush with petrol, and pour in Gas Plus!
 

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Just another thought, the long nuts that Don spoke about only seem to be available in UNC in the UK (they are called coupling nuts), you can get them in the USA, but not a lot of help there. However, the 21-2177 long nut used on the outer cylinder base of a T140 may well do the same trick. That's assuming that the 5/16" head studs have not been put in upside down with the plain bit sticking up.
HTH
 

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Hi Alex,
You do have a task ahead. It is going to be trial and error or a combination of things that work for you.
When the engine stopped it is likely to have stopped on compression of one cylinder, so there is a chance that the engine settled at or near top dead centre. It is a useful position for the engine to stop as you can then pull against the crankshaft without it turning.
Can you confirm the engine is at or near tdc?

I can see the pictures of the bike when you got it, but do you have pictures of it now, it would be interesting to see if the engine is still in the frame. If the engine is still installed you can use the frame to apply load.

you say that you have the nuts and bolts out of the head, this means that you must have taken the rocker assemblies off to remove the hidden inner head nuts under the rocker assemblies.

When the engine stopped it is likely that one or more valves were open on one cylinder and the valves were closed on the other. Damp air gets in through the open valves (more with the exhaust) so it is likely that one cylinder is seized worse than the other.

When you took the rocker assemblies off did all the valves close, and did they seal. You said that you have the spark plugs out. If you can pressurise the cylinders with air, then 100 psi on both cylinders will give 1400 pounds downforce, 150 psi will give 2100 pounds downforce. This could move the pistons or assist with other measures- rocking the crank/heat, etc. But you must have all of the cylinder head bolts in and tight (otherwise you will blow the head gasket and the rocker boxes off (otherwise one set of valves will open). If the pistons do not move it still might help in forcing the penetrating oils past the stuck piston rings, increasing their effectiveness. You have to be careful with compressed air though, it’s a lot of stored energy, when things free up they tend to fly. As already mentioned grease is often used, being incompressible any pressure dissipates instantly without being explosive.

As you have not broken any fins off of the barrel or head, We can assume that you already know that any levering of the barrel/head will very easily damage them.

with the exhaust and carbs removed, short lengths of thick wooden dowel jammed in the inlet and exhaust ports provide reasonably strong anchor points to apply force to, without risking damage.

ratchet straps around the frame (if engine is still fitted) looped around the above mentioned wooden dowels, could provide enough force or an assistive force along with other measures to either:
A) Remove the head, take out all cylinder head fixings and leave the cylinder base nuts on.
If the engine is at or near TDC.
B) Refit and tighten the cylinder head fixings and remove the cylinder base nuts.

I have added extra force before when removing a barrel when the pistons are at or near tdc, by placing plastic or wooden blocks on top of the cylinder base nut to spread the load, and evenly undoing the cylinder base nuts so the wood (or plastic) jambs between the nut and bottom fin. Be careful though.

if all else fails
If the engine is not at tdc, you might be able to remove the cylinder base nuts and turn the engine enough so that the barrel clears the the base studs. You should be able to split the crankcases with the head barrel still attached, it will be awkward. There is a hidden large diameter dowel in the front engine. mounting that needs to be removed, and a hidden bolt under the outer gearbox cover. The crankshaft head barrel pistons should be removable as one unit. Once this is done the big end caps can be removed leaving the head, barrel, pistons and con rods. Other measures could be taken from here (penetrating fluid on the underside of the pistons, precision mounting of the head/barrel in a mill to remove the centre bolts, etc)

good luck
Peg
 

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Hi, regarding the two middle cylinder head studs.

I once removed a stuck through-cylinder block bolt on a Honda 1100. It was locked by corrosion between aluminium and steel, thus locking the block to the crankcase. No hammering or oil/solvent allowed me to get it loose.

To get the job done, the engine needed to be removed from the frame.

What I did was:
  • With a dremel, cut the bolt close to the aluminium top surface.
  • Punched the bolt with a center punch and started drilling it away to just a little bit below the aluminium surface.
  • Took a suitable bit of steel tube and made it (very) thin walled to fit inside the hole in the block, and also to fit the outside diameter of the bolt.
  • With the drill bit, removed a few mm of the bolt with the tube as support. The tube prevented the drill from removing aluminium from the block.
  • Removed the drill bit and tube and cleaned up the hole to allow for the tube to be inserted deeper.
  • Continued until the enough of the bolt was removed, so I could remove the cylinder (in your case, the cylinder head).

The problem I had hopefully would apply to your cylinder head as well. Quite a bit of work, I know. Since in my case the cylinder block was stuck to the crankcase, this saved me from scrapping the engine.

Helge.
 

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Discussion Starter · #18 ·
What a day. I'd be far more despondent if you weren't here, offering advice and encouragement

Mick, great idea! The long but fits. Tried every bolt I took off bike, none fit. Do you know the spec of these two central bolts?

Peg; thanks for the detailed reply. ATF leaks out of the exhaust ports, so pressure won't work
The pistons are a long way down. I ripped in 750cc of ATF/acetone. Sticking a screwdriver in, from top of plug thread to back of piston is about 13cm.
I've cut up two curtain poles, done as you suggested. So far not budged, but can relax knowing there constant pressure applied.

I'll try splitting crankcases in a couple of weeks if no joy. Almost embarrassing to say, so far can't get cylinder barrel higher than about 8mm at back,4mm at front. Problem for another day

Alex

IMG_20210526_155143669_HDR_crop_37.jpg
 

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Another suggestion now that you've got upward pressure on the head , try putting the 2 central head nuts you removed
back onto the studs and thread down around 1/2 way . Then smack them sharply with a hammer and continue adding
as much upward force as possible with the straps and continue . Worth a try :) Peter
 

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Discussion Starter · #20 ·
Ok, I'll give them a smack. Well deserved, too

I was wondering, maybe I could permanently glue the original tall hex heads onto the studs. Would mean buying new studs, small price to pay. Does anyone know what I could use. It would need to withstand a lot of torque, as other studs were relatively easy to get out. Relative to other deep rusted nuts.
 
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