T120v Shed Find

It should already have a single-lipped roller bearing main on the drive side.Get the 3-piece double-lipped roller for the timing side,instead of the ball bearing.Both roller bearings will be CN internal clearance.

Siezed spark plugs aren't much fun,and sometimes never come out without taking all the threads in the head with them.Cut it off above the hex,punch out the centre electode,then drill the body with a 1/2" drill.You should be able to peel out the remaining thread like a helicoil.Use anti-sieze next time.

Weld a bar onto the crankcase plug and grind it off after you loosen the plug.Removing the plug is not a normal service issue,and can even cause return oil pump failure.It's best left alone for the life of the engine after you do the rebuild.

cheers for that.
Got the clutch off tonight.


old BMW timing sprockets are handy.

72Combat said:

Got the clutch off tonight.........old BMW timing sprockets are handy.

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Great thread, thanks for posting. Looks like you're making really good progress. Cj

Ditto :

Stator & Timing cover OF , lift the ends of the crank , before splitting the cases .
You can feel if theres a slight clunk, if any . Or 20 + thou. slack in the Ball races , :mrgreen:

The olde story was the things ran smoother with ball races , as the accomodated the crank whip better . But the ball races wore sooner .
the TIMEING side ran a open end roller , to accomodate the expansion . thus the DRIVE side bearing Locates the Crank , and the primary in line .
With Dual Ball races , for higher output - you get a bit of shuffle as the bering shifts in the case on the right- as it heats up . Can lead to spinning but Not Likely IF the bearing / case clearance is correct .

Theres likely a shim between the crank shaft one of the Main bearings , there . If theres no slack or pitting in the mains - Im not sure Id mess with them . Theyre fairly long lived if its been looked after .

SO theres a end float requirement in the timing side bearing . Wondering if theres a Superblend Barreled roller compatable for the best of both worlds . Setting the end float correct , of course .
This would likely smooth the unit which hace a harder burr to ' The Vibes ' than the more flexable pre Units , whichll rev freer with the Ball races and Single Run Primary . :lol: MORE H. P. 8) :twisted:

You need to carefully drill the peen mark on the sump plug, NOT the crank cheek. Welding on a cheater bar is a great idea, I weld on a large washer (on the I.D.) then weld a large nut onto the washer; works a treat.

Go back in with a new allen head plug, even though the greatest likelihood is that you'll never be back in there in your lifetime.

One more thing to be careful of is mistake in the 650 manual,regarding conrod bolt torque.The torque figure was revised in June 1969 to 22 ft-lbs (dry threads) ,with the introduction of UNF threads on rod bolts.This new torque figure never made it into the manual,and the old figure of 28 ft-lbs was not revised.There was a dealer bulletin 317 in July '69 about the new rod bolt torque.
You can always use the elastic bolt stretch to get it right (0.004"-0.005"),which will work even with lubricated threads.

It's not worth changing rod bolts,unless you upgrade to ARP bolts.Everything else is suspect,and not up to original quality.

First light to fall on timing gears since 1972.


Look Ma no case screws!!!??

Crank out, bearings good.

A productive afternoon at Mates saw the valve guides K-lined, the sparkplugs snapped off...and drilled out to about 1mm wall left.

Got a file and made the wall a bit thinner then used special tool and a hammer....

ran a tap thru the hole and its 'usable' , going to get that sorted.
Gearbox looks ok at first glance
was pretty sludgy.

Munted it getting it out.

The sump plug refused to budge, have to think about
that one,time for a beer.
Got sidetracked helping my Son take the Alternator out of his Toyota Levin......its at the back of the motor and it looks like you have to drop the axle off to get it out.....I hate working on cars.

I'd tap the correct socket onto that plug, then use an impact driver to remove it, or take a breaker bar to it and smack it smartly with a steel hammer.

grandpaul said:

I'd tap the correct socket onto that plug, then use an impact driver to remove it, or take a breaker bar to it and smack it smartly with a steel hammer.

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That and a bit of heat ( and swearing) did the trick. :mrgreen:
Measured up big ends, like new.
crankcase was 1/2 full of oil and mains look like new too.
no lip on bore and pistons are good, clearances are good.
Head needs two inserts and some guides.
Looking good.

I hope they're exhaust valve seat inserts,because intake seats aren't much fun.
You'll also need the larger diameter washers on th headbolts inside the rockerboxes,as mentioned in the link I gave.The small diameter washers may have already crushed into the head (which reduces bolt tension,time after time),and could require some spot facing on the head (especially on the exhaust side).

I would remove the engine from the frame. Don't force anything by smacking it. I used this method on my basket case 72 Commando:

Remove the cylinder head,drain any oil that may be left in the sump or gear box.

Obtain a propane torch that is used by "roofers" to adhere melt down roofs. These usually have a wide "rosebud tip"

Heat the jug using the torch getting even heat all around. While the jug is hot take a candle and melt candle wax around the circumference of the pistons.The candle wax in liquid form will penetrate better than any solvent.... This is an old machinist trick.

Repeat this heating process a few times.

Then with the jug hot use a heavy hammer and a block of wood as a drift you should be able to break the pistons free.

When the process is done you will see how the wax has penetrated and coated the pistons sides.

Best of luck with your bike,I love those "Euro" tanks fitted to home market bikes.........PhillySkip

Interesting how some like the US tank and others like the Euro ( breadbox) one.
Got the head back , mate fitted K liners to guides, head shop supplied new exhaust valves as one was bent.... and reseated the valves and slight resurface on the face.
Cylinder bore is good but one piston is more worn than other, looking at the Hepolite ( made in Taiwan or China) ones on offer $ 200 NZ.....its $80 just for rings.
Gave the rear suspension and swingarm a clean and grease, front hub is a PITA as I need a 1 1/8" socket to take the brake plate off :evil:
Looking at some of the repro fork sliders, Andover Norton has some pics of bent ones saying beware.

72Combat said:

Interesting how some like the US tank and others like the Euro ( breadbox) one.
Got the head back , mate fitted K liners to guides, head shop supplied new exhaust valves as one was bent.... and reseated the valves and slight resurface on the face.
- - - - - - - - - - - - - - - - - - - - - - - - - -
Looking at some of the repro fork sliders, Andover Norton has some pics of bent ones saying beware.

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They'll tell you never to mill a head on a Triumph twin.It creates problems with pushrod tube seal crush (which should be 0.030"-0.040") and increases the chance of bending the head if PRT seal crush is excessive.Heads can be straightened,but it's usually not necessary if the bow is less than 0.010" from flat.

Are you replacing the cast aluminium sliders or the stanchions?Replacement stanchions sometimes need the threads relieved a little at the start,so the nuts screw fully in.

X-file said:

They'll tell you never to mill a head on a Triumph twin.It creates problems with pushrod tube seal crush (which should be 0.030"-0.040") and increases the chance of bending the head if PRT seal crush is excessive.Heads can be straightened,but it's usually not necessary if the bow is less than 0.010" from flat..

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That is true, however over the years sometimes ham fisted owners do warp the head and milling flat is necessary. To overcome the crush on the tube seals, standard copper head gaskets are .050" and there is an oversize available at .080" (2mm). There is a slight drop in compression ratio, but the thicker gasket does the job.

If you can find a crank with the heavy flywheel, I'd buy it and get it reground and fit it with new bearings. The light flywheel is less desirable - the bike never seems to be as good. The light flywheels came out with the Triumph Saint 650 - did not perform. Somewhere you need to fit a pc valve so there is a vacuum created in the crankcases at least at low revs. Otherwise you will have to be very good to stop it from pissing oil. You will probably find the inlet cam will be part no. E3134. There is the same grind available on the exhaust cam with the points extension - not a bad way to go. The E3134 cams were the T100 race kit cam of about 1954 and two were used in the 1959 T120 Bonneville. Unit motors came out with an E3275 grind or similar on the exhaust. The race exhaust cam gives a real performance boost in a 650 or 750 and makes for a lovely ride.

acotrel said:

E3134 cams......two were used in the 1959 T120 Bonneville.

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Are you sure?

Didn't Bonnevilles up to around 1967 have E3325 profile on the exhaust cam?

Update, moved it on to my race mate who is a real Triumph fan. :lol:

Triumph cam PART numbers, PROFILE numbers, CASTING numbers, and STAMPED numbers varied and cause confusion more often than not. SOMETIMES one or more numbers happen to correspond, NOT ALWAYS.

There is a good, comprehensive list that covers most of what is known about all of these various numbers. Sorry, forget where the link is; if you google it, you'll find it.

Try using an air impact on the plugs dialed down to a lower air pressure. Let it hammer the plug a little, it should remove it. My also have to use a little heat the help expand the threads in the head with WD40. Good luck, and don't over do it.

Kind of small in the bottom of this photo, but here's a similar Triumph to what you found. I took this photo in 1975 at Hahn Air Base in Germany....outside my barracks window.