suzook12
Well-Known Member
I can only think it's for if the magneto stops turning it doesn't damage the engine, nothing else comes to mind
TR6- And So It Begins
- Thread starter suzook12
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Lordmac
Well-Known Member
LUCAS! I mean, who else? Fiber-epoxy/bakelight/plastic gears. Makes TOTAL sense.
Reminds me of the timing gear on my 1971 Saab Sonett 3. Some type of fiber composite, I could never imagine such would be put in any critical spot in in an engine!
Yeah, some engineering reason for sure.
suzook12
Well-Known Member
I guess maybe they thought the mag was more prone to seizing, especially as it wasn't lubed, and figured best to rip the teeth of the mag gear than the cam gear and start bending stuff? That's all I can can think of
suzook12
Well-Known Member
Couldn't possibly be because the gear broke up all by it's little self could it?
suzook12
Well-Known Member
Ok, had a house clearance to sort over last couple of weeks so had very little time for this. Had a quick butchers today after finally getting to fit the lathe levelling feet and some sort of level on the lathe.....
So something that caught my eye a while back was the angle of the swingarm looks incorrect. Shocks are 325mm between centres, which as far as I can find are the correct length? There also seems to be little in the way of ground clearance, so something clearly going on.
Thoughts?
Also turned the motor over with the timing cover off. Doesn't seem to pump much oil, something else to look at
Hoping to get on with this very soon, get the motor and box out and front and rear out so can get the frame looked at...
More soon
So something that caught my eye a while back was the angle of the swingarm looks incorrect. Shocks are 325mm between centres, which as far as I can find are the correct length? There also seems to be little in the way of ground clearance, so something clearly going on.
Thoughts?
Also turned the motor over with the timing cover off. Doesn't seem to pump much oil, something else to look at
Hoping to get on with this very soon, get the motor and box out and front and rear out so can get the frame looked at...
More soon
suzook12
Well-Known Member
Little to update as been full on with other stuff.
Did happen across a complete alternator setup from a honda G5, so thats gone in the "possible" box, possibly also sourced a proper tank for it. Getting an idea of where I want to go with this now.
Anybody know if the 750 pistons fit the rods, thats another possibility
Did happen across a complete alternator setup from a honda G5, so thats gone in the "possible" box, possibly also sourced a proper tank for it. Getting an idea of where I want to go with this now.
Anybody know if the 750 pistons fit the rods, thats another possibility
There are 750 kits (block and pistons) for the unit 650, the unit 650 kept the same bore spacing and stroke as the pre unit.
73 on 750 have shorter rods and shorter block, to reduce the engine installation problems in the oif.
suzook12
Well-Known Member
Ok cheers, from what I can find the 750 pistons are 76mm and PU 650's 71mm? What I can't seem to find anywhere is the wrist pin sizes. I suppose new rod bushes taken out to new size would solve the problem anyway
Basically ...
All 650 (except the '82 TR65), pre unit and unit, are 71 mm bore.
Early 73 "750" are 75 mm bore (724 cc), most are 76 mm bore (744 cc).
All 650's (except the '82 TR65) - pre unit and unit - and all 750's are 82 mm stroke.
All 750 made by Meriden have a reduced height block (one less fin than 650 blocks) and shorter rods.
The Aerco/Velocette "750" kit that fits certainly unit 650 is just a block with bigger holes and bigger pistons, not shorter block/rods.
The above applies to 4 valve twins. Meriden made an 8 valve twin (82/83 TSS) that is a lot different.
Rare and earlier, Rickman also marketed 8 valve top ends, made by Weslake iirc.
Last bushed 650 rods were 72, still the same E1511 as the pre units.
Check with a long time dealer like TMS?
suzook12
Well-Known Member
Cheers Rudie,
Some useful info there.
Effectively, with the longer rod, the 650 will make a better 750 as crank angle is better, and effectively, if crank spacing is the same, then theoretically an 850 should be possible.
I wonder how far these engines got pushed back in the day? I know a mate of mine used to run a methanol burning supercharged triumph in drag iirc, it was sat in another mates lock up back in the 80;s
speedrattle
Member
people still push them.
^^^this one goes 175 on nitromethane
a friend of mine built this double. still needs development, but it went 142 on its first run.
both of these are naturally aspirated, but the original intent for the double was nitrous. it would be good for 180 to 200mph with a bottle
^^^this one goes 175 on nitromethane
a friend of mine built this double. still needs development, but it went 142 on its first run.
both of these are naturally aspirated, but the original intent for the double was nitrous. it would be good for 180 to 200mph with a bottle
suzook12
Well-Known Member
Had some spare time today, so got the spanners out....
Now I would assume the clever bods at meriden would have sat the engine centrally in the frame? Really struggled to get a couple of rocker box bolts out without fouling the frame.
Got there eventually..... As for the no compression mystery, I think it's fair to say that's no solved....... Valves look ok, valve train moving ok, no brocken rockers etc, but valve timing about a week out!! There is also quite a bit of piston crown damage to one piston, the piston crowns look different heights and I caught someone trying to drive a bus between the pistons and bore.....
Isn't it fun trying to undo stuff that has had 200 years of wringing off and burring over
Now as this is a TR6 motor, I assume it should be alloy head and barrels, 8 stud? If so, as it looks like I have to buy pistons etc anyway, may as well get a new top end for it as well or is there not much in it between them? Will be ordering the cam tools shortly, so should hopefully have the bottom out and split fairly soon, then can start rebuilding
Now I would assume the clever bods at meriden would have sat the engine centrally in the frame? Really struggled to get a couple of rocker box bolts out without fouling the frame.
Got there eventually..... As for the no compression mystery, I think it's fair to say that's no solved....... Valves look ok, valve train moving ok, no brocken rockers etc, but valve timing about a week out!! There is also quite a bit of piston crown damage to one piston, the piston crowns look different heights and I caught someone trying to drive a bus between the pistons and bore.....
Isn't it fun trying to undo stuff that has had 200 years of wringing off and burring over
Now as this is a TR6 motor, I assume it should be alloy head and barrels, 8 stud? If so, as it looks like I have to buy pistons etc anyway, may as well get a new top end for it as well or is there not much in it between them? Will be ordering the cam tools shortly, so should hopefully have the bottom out and split fairly soon, then can start rebuilding
suzook12
Well-Known Member
Got a little bit more done today.
View: https://youtu.be/SzcQJDRmZS8
Just gotta figure how the clutch comes apart so can get the primary case off, then engine out.......
View: https://youtu.be/SzcQJDRmZS8
Just gotta figure how the clutch comes apart so can get the primary case off, then engine out.......
Unit 650, Triumph added a ninth bolt through the head into the block between the cylinders on the exhaust side. 750 upgrade kits have the thread in the block for this.
73 on 750, Triumph added a tenth bolt through the head into the block between the cylinders on the inlet side.
Afaik, increasing a Triumph twin's capacity beyond 750 is not done by increasing the bore i.d.:-
. early 73 750 are 75 mm bore, barrel casting thickness is increased near the base to allow 76 mm;
. practically, increasing a Triumph twin's capacity beyond 750 is done with a Norton 89 mm stroke crank.
suzook12
Well-Known Member
Cam gear tool/s ordered today.
Will fashion a couple of clutch tools today hopefully and have primary case off and engine out. Least thats the plan. That will be the end of engine for now, Will be looking to get the frame stripped and jigged and ultimately repaired and cleaned up. Then starts the long road of rebuilding
Will fashion a couple of clutch tools today hopefully and have primary case off and engine out. Least thats the plan. That will be the end of engine for now, Will be looking to get the frame stripped and jigged and ultimately repaired and cleaned up. Then starts the long road of rebuilding
