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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

View attachment 756081
Hello Alex, those studs are 5/16” UNF, most of the 5/16 bolts on your bike should be that thread, but goodness knows this far down the line!
 

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Hi Alex, Checking my stud remover, it’s too fat to reach the stud deep enough to get good grip. The collet removers would be similar. So your back to double nutting or the like.

The thread is 5/16-24. That is certain unless someone has custom cut threads. I just removed my by double nutting. Of course head was off.

The coupling nuts sold here are 7/16 hex. Here is one compared to the head nut. Threads in head nut is same length as coupling nut. You could use the head nut & grab it with mole grips to loosen. I see even on UK eBay coupling nuts are quite costly. $4 each at my local hardware store. We are lucky as they have good stock of Course & fine threads, plus metric. I don't know if a local bolt supplier in UK would stock 5/16-24 nuts. I don't know if you can buy SAE thread fasteners locally or not.

The front fender lower strut bolt at axle cap is correct thread. I don't know if long enough to reach past hex in head nut??

One thing you must own is UNC. SAE thread tap/die set.

If you can get 5/16 bolt locally with enough thread you can make a thread cleaner by cutting 3 lengthwise slots in threads. Then run a nut over to deburr. I've made many. Actually just used them on my bike recently. I use cutoff wheel in Dremel to cut. One thing for sure. It takes a lot of tools to work on a Triumph....

It may be the unwinding of stud will allow it to release & the rotational friction will be less & can unwind out of corrosion.

You'd have to be much better than me to drill the stud out. I'd make a drilling guide from 2" thick steel. I have a good workshop, most don't I get that 100%.
If cylinder will lift out of studs you could remove motor & split cases with cyl/head intact. Unscrew rod caps. The T140 doesn't have the 2 hidden screws at cyl base area. A machine shop could mount cyl in mill & drill the stud without damaging head.

I'd do some careful online research on chemicals that may dissolve corrosion. Is the stud magnetic? Mine are non magnetic stainless. However if studs age from high heat they can become partly magnetic. 2 of mine did that. They will be replaced.

I know white vinegar works very well for me cleaning corroded carbs.

If you split cases & removed rods/cyl, once you got head off, you could press pistons out. What about rust remover chemicals to remove rust, then press out or push out? I don't know, just thinking out loud.
Don
 

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I saw a tv prog where to release an engine they heated a pan of oil over a stove until it was boiling and poured it through the plug hole. Obviously this needs care in both the heating, transport and pouring of a pint or so of boiling oil.
My central bolts are allen type?
If you can get the pistons to move then shoving rope down the plug hole can help break a bond between head and cylinder
 

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Hi Alex,
The cylinder centre bolts should look like this:
756138


There is something else that is strange:


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.
If you have removed the cylinder base studs at the bottom of the barrel, and the pistons are stuck when you lift the barrel the cylinder should lift by at least the 130mm that the pistons are down the barrel. As you lift the crankshaft should turn (you have confirmed the pistons are not at TDC (13cm down). When the crankshaft turns, the barrels should lift. I would conclude from this that there is something else preventing the crankshaft from turning.
I would remove the primary cover and the timing cover to investigate this futher.
Regards
Peg.
 

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Discussion Starter · #25 ·
Hello Peg.
My central studs are like that, have removed the tall hex nuts. It's the studs that need taking out.
Every thing in primary case looks almost new. No movement. The clutch cover moves out very slightly when trying to turn back wheel
Alex
IMG_20210527_105741538_HDR_crop_39.jpg
 

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Discussion Starter · #26 ·
Just to add, primary cog moves freely in neutral.
Clutch seized, have handlebar lever tied to bars for couple of weeks, hoping it might release.
 

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Don't hold your breath for that to happen . However there's only the 3 screws that have to be removed to allow access to all the plates , remove ,
separate , clean and reassemble . Peter
 

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Discussion Starter · #28 ·
Ok, thanks Peter.

Update in trying to remove center studs:
Long nut and bolt wouldn't grip tight enough. Drilled hole through tall hex nut into stud. Stuck drill bit in. Used long ratchet--stud very firm. Hex nut snapped in half.
Now going to buy some red locktite, use in other hex bolt and stud, see if it holds when attempting to unscrew stud.
 

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You will need to double nut it if you want it to work . As much as I love red loctite for "never fall off again fasteners" it isn't strong enough
to allow you to remove a seized stud with a single nut locked to it . Peter
 

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Discussion Starter · #30 ·

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Thread a compression tester fitting into a spark plug hole and hook that to an air compressor. A real air compressor not some little weenie one. Stand the heck back when you do it. Either the head will go up or the piston will go down.
 

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If the nuts are off, why do you need to remove the studs. Kroil and lots of heat should get the head off. Hit the studs while lifting head.
 

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Discussion Starter · #34 ·
If the nuts are off, why do you need to remove the studs. Kroil and lots of heat should get the head off. Hit the studs while lifting head.
I've heated cylinders until ATF is boiling, whacked with a mallet. Tied to frame and pulled down using back wheel. It's totally stuck
 

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Discussion Starter · #35 ·
Here's an update. Took two days, 1mm up 1/2 mm down. Now got barrel off, using back wheel and Peg's idea of wood posts.
What shall I do now? Split engine? Still can't access pistons to whack or take off. Head still stuck.
Good news is, all the back wheel tugging has separated the clutch plates
IMG_20210529_132434438_HDR_crop_97.jpg
IMG_20210529_132434438_HDR_crop_97.jpg
IMG_20210529_132402695_HDR.jpg
 

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Discussion Starter · #36 ·
I thought maybe take ATF out if cylinders and pour acid in.? Pistons will be ruined, but can put towel underneath to stop acid dripping into crankcase, now it's lifted clear. Might free cylinders, although I'm expecting not
 

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You're going to hate me for saying this, but I would bolt down (loosely) the barrels again and keep working on that head the way you were. It will come, just need the patience of a saint.
 

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Discussion Starter · #38 ·
Ooo, I hate you!
Ok I'll try it. Might go back on, and off easier now-- there were a couple of shims around the studs I'll remove.
Not today, I'm done for today
 

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The "shims" should be locating dowels which are part of the studs.
Acid is likely to ruin other things besides the pistons, I would avoid it.
If you put the cylinder back down with the nuts just engaging so the cylinder can move slightly on the studs, put a wrench on the generator nut and work it back and forth. The play on the cylinder studs should let you get a little travel on the wrench.
Or you could let the head/cylinder hang from the straps and use the generator nut to lift/drop the cylinder to jerk on the pistons.
 
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