Triumph Rat Motorcycle Forums banner
41 - 60 of 115 Posts

·
Registered
Joined
·
8,700 Posts
I’ll change all the bearings while I’m there anyway. I would have thought even the daftest person would have sandblasted the pistons out of the bike and cleaned them. The other bore is in good condition so hopefully that’s not the problem but we’ll see. This could be getting expensive.
The sand would have embedded into the alloy, hence all the scoring. The pistons would have been away from the engine alright but should never have been blasted. The whole engine and all its parts will need many washes to make sure all the grit is gone. It is a recently built engine and just look at all those vertical scores on pistons and bores. Fascinating to see how someone can do so much damage during a rebuild.
 

·
Registered
Joined
·
123 Posts
Discussion Starter · #43 ·
Well hopefully I’ll do it it right this time. On a side note are Conrods usually changed on a rebuild. I’m presuming they are the original ones. And what’s required for the cylinder head.
 

·
Super Moderator
Joined
·
13,823 Posts
Well hopefully I’ll do it it right this time. On a side note are Conrods usually changed on a rebuild. I’m presuming they are the original ones. And what’s required for the cylinder head.
Conrods need to be checked for roundness on the big ends with the shells removed and the nuts snugged. If there's no slop in them, they're PROBABLY good. No need to replace if they round at the bottom and have no nicks or deep scratches.

Cylinder head LOOKS reasonably clean, compared to MOST of the heads I've had to overhaul. You can use your dial guage and check the slop, I know the book has a spec for that. Use a magnifier and look closely at the valve seats after you scrub them up. If not nicked, gouged, or scored, not likely you'd have to replace, just lap with coarse, then fine lapping compound.
 

·
Registered
Joined
·
123 Posts
Discussion Starter · #45 ·
Just waiting for the clutch tool to arrive and then the investigation can continue.
 

·
Registered
Joined
·
962 Posts
Ah, Notlob, for those who remember Monty Python, 'fraid I'm near Princes Risborough in South Bucks, not exactly close!
 

·
Registered
Joined
·
8,700 Posts
I was thinking of loaning the engine tools but too far away. That pinion puller is very expensive and possibly not use it again for many years. Clutch tool and clutch locking tool is something you will often use. The small end bushes can be removed with something you make up easily.
I have never had to replace con rods on a bike just used on the road sensibly. Not even had to replace valve guides on any bike i have owned long term. Just check it all as you take it apart.
next surprise could be the crank journals if sand blasting grit has got in.
 

·
Registered
Joined
·
123 Posts
Discussion Starter · #50 ·
I was thinking of loaning the engine tools but too far away. That pinion puller is very expensive and possibly not use it again for many years. Clutch tool and clutch locking tool is something you will often use. The small end bushes can be removed with something you make up easily.
I have never had to replace con rods on a bike just used on the road sensibly. Not even had to replace valve guides on any bike i have owned long term. Just check it all as you take it apart.
next surprise could be the crank journals if sand blasting grit has got in.
I’ve ordered the clutch tools see if I can get round the pinion puller when I’ve split the cases. It’s fingers crossed at the moment just have to see what I’m dealing with.
 

·
Registered
Joined
·
123 Posts
Discussion Starter · #51 ·
Yes Stuart I’ll ask advice on what to check when I get the cases apart.
 

·
Registered
Joined
·
960 Posts
Where are you in the UK, I’ve got lots of stove enamelled barrels with mostly new pistons sitting on the shelf - ask Alex The Biker!
There's not a square inch of free worktop down at Mick's place. Goodies everywhere.

Unfortunately, Mick, I stripped that ultra-seized and mega-rusty T140 to the very last but one bolt; never managed to get sludge-trap cap off, can't hold crank from moving. It's in boxes upstairs.

Still, lovely cylinders!
 

·
Registered
Joined
·
1,711 Posts
Do it right your looking at a good 30-40k miles of trouble free service
If you ride in a conservative manner, yes..If you enjoy a sporting ride ,tearing up the back roads, you engine life will be less depending on the build quality.
 

·
Registered
Joined
·
962 Posts
There's not a square inch of free worktop down at Mick's place. Goodies everywhere.

Unfortunately, Mick, I stripped that ultra-seized and mega-rusty T140 to the very last but one bolt; never managed to get sludge-trap cap off, can't hold crank from moving. It's in boxes upstairs.

Still, lovely cylinders!
If you are over this way, I can get that plug out in minutes in my fly press, but don’t even think about bringing it on the back of the bike!
Or stuff it in a strong box and send it! (No, not the bike)
 

·
Registered
Joined
·
2,811 Posts
Well hopefully I’ll do it it right this time. On a side note are Conrods usually changed on a rebuild. I’m presuming they are the original ones. And what’s required for the cylinder head.
I always replace the rods with the superb billet connecting rods made by Thunder engineering.
the alloy is at least 40 years old

However, there is an argument that if the big ends measure round and the big ends and little ends are parallel and the rods are polished free of stress riser nicks and scratches and it is not a race engine you are building, then the con rods might be acceptable to reuse.
I will always replace, but maybe that is overkill on very expensive items.
After thorough inspection, you will be able to evaluate whether it is worth it to you.
One thing that is worth doing, is matching the piston weights, and the con rods, not only for absolute weight but for end over end. It costs a little time and care.

There is a fine line between an engine that is a delight or purgatory to live with. Now you have the cases open, you have the opportunity to decide which side of the line you want to be on.

Good Luck
peg
 

·
Registered
Joined
·
962 Posts
The T140 rods are much stronger than the 650 ones, the Lightning ones are too beautiful to put inside a dirty oily engine. Best put pride of place on a sideboard (or other favourite furniture), but as Peg says, some balancing is well worthwhile.
 

·
Registered
Joined
·
123 Posts
Discussion Starter · #58 ·
Thunder engineering look like a good setup. When I inspect the conrods the decision might be made for me with the way it’s going so far.
 

·
Registered
Joined
·
2,811 Posts
Hi
Good stuff, but WAY over the top for a typical classic bike that won't be thrashed constantly.
Hi Gpz,
Not over the top for me.
The original alloy rods do get affected by age, I have a (maybe unjustified) mistrust of the old items with unknown history, so I would rather change them.
A standard replacement pair of con rods in the UK are roughly £270 to £300. For a connecting rod with traceability back to the retailer.
This means I have no idea of what it is i’ve bought, I have no Idea of the materials used, the machines it is produced on, the skill of the engineer, the CNC programming used, or the country of origin.

The Thunder Engineering rods are more expensive maybe £100-£150.
But I get traceability back to the manufacturer, within 2 hours ride I can be talking to the guy who makes them (Steve is great guy). He uses the highest quality appropriate materials, a proven very strong design, high skill levels and I know where the origin is, because I can see them being made.
I know they will be perfectly weight matched, and end to end balanced.

Most importantly I am supporting a local British, high quality business- we need businesses like this to survive.
There is a value here to "Made in Britain’ the same as "American Made’ for the USA. Knowing my purchase will put tax money back into the education and health services of the country that I live in, is a comfort.


I get complete peace of mind that they are not going to break and I get to admire them, before they are hidden away in the engine.


regards
Peg.
 
  • Like
Reactions: rambo

·
Registered
Joined
·
8,700 Posts
If i were to ever buy conrods, i would buy the Thunder Engineering too.
 
41 - 60 of 115 Posts
Top