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41
A7 & A10 Engine / Re: Engine oil blow out
« Last post by limeyrob on 16.10. 2024 11:53 »
Unless something is loose the serious vibration will be from the pistons and crank. Piston weights vary quite a bit between makers and I'm not persuaded that the "basic" balance set is the best.  I bought an A65 new and while it was smooth at low revs it vibrated a lot at high revs and being a over square engine it needed revs.  I later built it with high comp pistons that were significantly lighter and I was expecting problems.  It was much smoother so my conclusion was that BSA were not optimizing the balance.
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Other BSAs, Other Bikes, Cars, Machinery & Tools / Re: Over reving a Trihard T120R
« Last post by limeyrob on 16.10. 2024 11:46 »
Those don't look like 9:1, i could be wrong, but are you sure?
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A7 & A10 Engine / Re: Engine oil blow out
« Last post by Craigy on 16.10. 2024 11:13 »
…..and it really does vibrate - rattles your eyeballs 😳

I haven’t been able to work it out yet, it’s ok when it’s pulling but on constant revs/deceleration it really vibrates.

I’ve had a feel around different parts while I’m riding but can’t seem to trace it. I know the drive chain really shakes at certain revs during tick over, so I’ve played around with that and the primary chain but it didn’t seem to make and divergence to the initial vibration …..just another problem 🤔
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Other BSAs, Other Bikes, Cars, Machinery & Tools / Re: Over reving a Trihard T120R
« Last post by muskrat on 16.10. 2024 11:10 »
G'day Fellas.
I've got onto a set of barrels that are std but need to go out to +20 for $200. I'd already ordered +60 so will try to sell them.
I doubt very much that I would have used "no name" pistons (9:1), I haven't checked the clearance (will after dinner). I have flushed out the cases, oil tank and hoses. Tomorrow I'll pull the oil pump and have a good look.
I asked Rossco if he'd topped up the oil in the primary. He hadn't as he only did a few hundred miles since he got it. The primary was overfilled by about 1200ml  *eek* I'd better check the g/box. There wasn't much in the oil tank (oil in frame) either *ex*
Now to find a reputable borer, my fella died a few years ago.
OK piston to bore 0.005", filter on the sump plug had a little swarf, oil pump all good. Looks like the timing side hadn't been touched as my green gasket was there.
Rear tyre is on backwards and 15 years old as is the front. Scotsman. See what I find tomorrow.
Cheers
45
A7 & A10 Engine / Re: Engine oil blow out
« Last post by Swarfcut on 16.10. 2024 09:23 »
 Craigy....If you have ordered a new feed pipe complete, better to leave it in one piece for now and ensure it is well supported, as suggested by Rob. Split small bore rubber tube lengthways as a cushion under P Clips or similar, you can always substitute a flexy
 if and when the quality part purchased eventually fail. The trick is to damp out vibration to the pipe as much as you can.

 Swarfy.

 
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A7 & A10 Engine / Re: Engine oil blow out
« Last post by limeyrob on 16.10. 2024 08:29 »
For reliability you don't want more than about 3"- 4" of unsupported copper pipe or any where its supporting anything.  Its the high frequency vibration that does for it.  If you can clip it back (put a rubber sleeve in the clip) that works too.
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Other BSAs, Other Bikes, Cars, Machinery & Tools / Re: Over reving a Trihard T120R
« Last post by limeyrob on 16.10. 2024 08:26 »
Do we know the comp ratio of those pistons?  Look like 10 - 10 1/2?  If the engine is tuned like that and being pushed it would need racing type clearances and be like a bag of nails cold.  I had a 73 T140 and it wasn't a fast bike.  The Bonnevilles of that period are around 50-55 hp and the Honda 4s are around 65+.  Within months of the CB750 going on sale in the States the roads were littered with blown up Triumphs. *sad2*
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Other BSAs, Other Bikes, Cars, Machinery & Tools / Re: Over reving a Trihard T120R
« Last post by groily on 16.10. 2024 08:03 »
Reckon that has to be a 'down to the last little washer' rebuild Musky. Nipped up?? That's a polite way of putting it!
Wonder how many flakes of 'inferior piston' are in the oilways?
If those aren't the pistons you put in it 30 years back, who knows if the skirt clearances were correct for whatever they are - looks rather as if they were inadequate or there was a lack of lube?
Presumably this'll be a new liners job now, or find a better set of barrels (and a person who can bore on centre)  . . . expensive, as you say, whichever way one goes.
Glad it's not mine. Quite enough hassle with that sort of thing this year already round here!

Playing games with Honda 4s and similar only ever worked for me, a bit, sometimes, on bendy roads, and even then  . . .  brakes - argh!
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A7 & A10 Engine / Re: Engine oil blow out
« Last post by Craigy on 16.10. 2024 07:46 »
I’ve stuck my order in for the parts, thanks for all the help and guidance.

I’m I right in thinking the the oil feed pipe 67-0450 is the one your talking about cutting and replacing with rubber to stop chance of fractures

Cheers……now just the long wait ☹️
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Other BSAs, Other Bikes, Cars, Machinery & Tools / Re: Over reving a Trihard T120R
« Last post by limeyrob on 15.10. 2024 21:47 »
"Those who fail to learn from history are doomed to repeat it"
In the 1970's chasing Honda 4's was the primary means of destruction for Triumphs
Tell your mate he's living history *smile*
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