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Discussion Starter · #1 ·
Alright, i'm looking for opinions.
1973 tiger tr7rv...750cc.

Motor was taken apart due to hollow tin tin top end noises ...mainly on left side. I have no vertical wrist pin wear and no lower end bearing wear...both stated from physical feel not visual or measured observations. Cylinders look pretty good... i'm used to 2 stroke honda 125 motorcycles... Pictures say a thousand words... should i..

a. hone cylinders, put new pistons and rings
b. bring to well repuitable shop for an estimated $1500 complete rebuild bottom up.

I do love the bike and don't plan on selling it... the $1500 is steep and i would rather rebuild the top end only... but i also want to make the right decision and not have to take this thing apart in a short time.










Thank You
Zach
 

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I'd just do the pistons. If there is no play in the rods, etc. why fix what's not broken? If you are sure of the miles and the past engine work, I'd keep the coin.
 

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It really isn't much more work to pull the cases apart and refresh the bearings.
Ask yourself: Where did all the metal from the pistons scraping the cylinder walls go?
 

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I would mike the bores see if they need a rebore if not hone them and fit new pistons and rings and go for it. The bore may be worn and the pistons rocking in the bore, $1500 for a top end job is highway robbery. Gearhead
 

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Discussion Starter · #6 ·
$1500 was the quote to rebuild the entire engine. So is this what we are leaning too.... i have not mic'd the cylinders yet..i plan to after work today..hmmmm
 

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$1500 was the quote to rebuild the entire engine. So is this what we are leaning too.... i have not mic'd the cylinders yet..i plan to after work today..hmmmm

$1,500 for top and bottom rebuild? Definately on the low end from the limited information Ive seen on rebuild costs. May I ask what shop quoted you that and what that includes. E.g. is that for a basic rebuild and may have to add on depending on what they find once they look?
Keep us posted -- ill be looking to do something similar soon.
Cheers.
 

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$1,500 for top and bottom rebuild? Definately on the low end from the limited information Ive seen on rebuild costs. May I ask what shop quoted you that and what that includes. E.g. is that for a basic rebuild and may have to add on depending on what they find once they look?
Keep us posted -- ill be looking to do something similar soon.
Cheers.

Back in the UK look to spend £4000+ :eek: for a full rebuild by top name company. Did have 4 pages of A4 listing the parts replaced/upgraded though.

Badger.
 

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Discussion Starter · #9 ·
Ok... i need assistance... obviously i do not want to drop the big $$ on the motor if i don't need to.

I have taken each piston off and made an attempt to get mic'd numbers off of them...i have put them skirt first into the bottom of the cylinder and find a good amount of play...

Now i have attached some more pics... i'm trying to figure out if these are suposed to be standard bore pistons or if they are oversize....the only markings i can find on the pistons are "T1176" and a number #1 under one piston and a #5 under the other..

I have an old Clymer manual... and do not find it user friendly

thanks







 

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that's just the casting # , normally the pistons are marked on the crown , the top , under all that carbon they should be stamped .
 

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Discussion Starter · #11 ·
Piston (left) 2.930-2.940...this was the noisy side
Piston (right) 2.986..+

i found my pdf manual with the specs...
 

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Imp88 , measure the pistons at the top just above the top ring . the bottom of the pistons are oval . sorry i don't have the specs for a 750 at hand .
 

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Do the whole thing. You'll probably need pistons by the look of it. That way you won't be recycling the dirt and scratching up the new parts. There's alot of scratching on those pistons. I'd want to clean the sludge and check the rod bearings to be happy.
 

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Please let me know who is doing complete engine overhauls on Triumph big twins for $1,500.00 with any kind of guarantee; I need to start sending them all my client engines so I can basically make 100% profit on the labor cost.

I cannot do a thorough engine overhaul for $1,500 in PARTS ALONE, at my cost!

Something ain't quite right with this picture.
 

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This just brought a question to mind for me:
Regarding special tools, specialized knowledge (or knowledge that is available but still hard to pick up) I wondering if I had a 60's Bonnie, where would my money/time best be spent?

I'm thinking contracting out the engine bottom end reubild is a good way to go. The top end I could get bored out locally and setup myself and all the other components to a restore, e.g. wiring, frame coating, wheels, all other bits, I could do myself or farm out locally.

But, as far as having to buy new tools and watch videos AND MAKE SURE I DONT SCREW IT UP then a bottom end rebuild done by an expert is probably a good way to spend your money.

Any opinions? Cheers.
 

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Please let me know who is doing complete engine overhauls on Triumph big twins for $1,500.00 with any kind of guarantee; I need to start sending them all my client engines so I can basically make 100% profit on the labor cost.

I cannot do a thorough engine overhaul for $1,500 in PARTS ALONE, at my cost!

Something ain't quite right with this picture.
Paul: what does your engine overhaul consist of? I looked at you websit but it was pretty general in terms of details.

P.S. Im not trying to advertise Pauls work. If its a problem just PM me the details. Thanks!
 

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Typical engine overhaul:

LABOR
Teardown & inspection
Rework crankshaft/lower end
Replace sludge trap
Rework pistons & cylinders
Rework head, valves, guides
Rework primary/clutch
Rework transmission
Overhaul carbs
Sandblasting, washing, cleaning
Polish Case covers (primary, timing, tranny & rockerboxes)
Re-assembly
Test & tune (install in frame)

PARTS
OIL SEALS & GASKETS
SLUDGE TRAP
ROD BEARINGS
MAIN BEARINGS
TRANSMISSION BEARINGS
CLUTCH PLATES & SPRINGS
CARB KITS
MISC. RUBBER PARTS
SPARK PLUGS
MISC NUTS, BOLTS, WASHERS
PISTONS & RINGS
PRIMARY CHAIN & TENSIONER
COUNTERSHAFT SPROCKET
ENGINE COVER SCREW SET
PATENT PLATE & PINS

Typically, where the crank journals don't need grinding and the valves & guides are okay, $2,500 is typical (parts & labor). If some core parts are shot, (valves & guides, clutch basket, rods, oil pump) it can go higher.
 

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By what I'm seeing from your photo's I believe I would go over the entire engine. Lots of wear on those parts. Do the rebuild and sleep easy knowing all is well inside your engine. Sure it will cost you some money but it will only cost you more if your engine grenades. Kind of one of those, "pay me now or pay me later" things.
 

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Just had a similar job with my 650.
Pistons had 0.013" taper, right piston is chipped, pistons scored.
But not as bad as your pictures.
Ring gaps are 0.019".
The bores were measured (not accurately) with inside caliper and mic.
As far as I was able to see, the left pot has average clearance WRT the piston of 0.009", the right 0.006".
Compression is 60psi...very low.
Just ordered new pots, pistons and rings. May do small-ends.
Hopefully the innards are OK.

In your case, I would like to be sure the bottom end and camshafts, etc are OK.
 
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