Les Harris T140 crank balance

In October this year I bought a "Les Harris" Triumph T140. The previous owner was my friend from France who passed away a couple of years ago and his son offered it to me to purchase. The bike hasn't been run since about 1999 and there was a lot of rust in the tank and evidence of many oil leaks, so I have completely stripped it to make sure all is well.

It is now more or less ready for re-assembly, but there is one problem that I can't make my mind up on. The Les Harris Bonneville's had the TSS crank fitted which in it's original state was a much more rigid design than the original having bigger big end journals and is fully machined and also heavier and I understand reduced vibration, but when fitted to the L.H. Bonneville's, was modified by having the big end journals reduced to the same diameter as the standard 650/750 but was otherwise left as the TSS, i.e. heavier.

I don't know if this bike vibration-wise is smooth or vibrates a lot? I never asked my friend, who obviously is unable to tell me now and I haven't run it at all since purchasing it as there were several issues with it and after purchasingI immediately stripped it down.

So my quandary is whether to get the crankshaft balanced or not, and if so, to what percentage as it is heavier than a standard T140 crank. I contacted Basset Down who are a well know balancing company in the UK and they confirmed that they have never balanced one of these cranks from the L/H Bonneville so has no feedback as to what works etc. Another person I know had theirs balanced to 81% and wasn't happy with it.

So should I;
1. Reassemble as is and see what it's like hoping for the best and if it's bad strip it down and send off for balancing with the known data?
2. Get it balanced leaving the balance factor as it is, but remove any "rocking couple?"
3. Any other suggestions.

I am tempted to re-build leaving it as it is, but to strip it down again is quite a bit of work.

Offending item is below.

Triumph did a supplement for the workshop manual for the TSS. I'm pretty sure it states the balance factor in there. TMS will sell you the supplement, they might even know the balance factor.
Basset Down did my TSS crank a few years ago. As I recall, I sent them the crank and rods and asked them to dynamically balance it to whatever factor it currently was!
I did it this way cos he TSS was so smooth prior to the re-build, but a I wanted 'to be sure'.
I would call them and ask if they are able to determine the factor from your components if you send them to them and work from there.
They are good strong, stiff cranks, but neither Meriden or Harris dynamically balanced them as ar as I am aware, so it would be wise to do so whilst its down IMHO.

Thanks for the advice Nigel.

I have emailed Bassett Down a few days ago, and they said they haven't balanced one of these (L/Harris T140) cranks before and that if I could tell them where the vibration problem was that they could probably work something out to improve it, but as you know, I don't know if there is a problem yet.

I did re-email B/Down about would there be any advantage in just getting the crank balanced to eliminate any rocking couple and they didn't reply, but as you say, they won't have been dynamically balanced so it will be wise to get this done and probably retain the existing balance factor for now.

Darrell from Rockerbox at Farnham has had his L/Harris T140 crank balanced to 81% and says it is quite vibratory, certainly not an improvement on what ??it was before.

OK, that's what I'll do. Thanks for consolidating my dithering.

Well I've got the crank back. There's a lot of holes in it! :shock: :shock: :shock: It looks like a piece of swiss cheese. :lol:

I asked Andy at Basset Down to balance my crank with a view "to remove any rocking couple" and "consider leaving the balance factor as it was, but I would trust him to do what was necessary," as my friend/acquaintance who was the previous owner and is now deceased so I couldn't determine if this engine vibrated badly or not, and as it was a none-runner when I got it, I also couldn't determine this either.

Andy has balanced it at 80% and says it was approximately at 75% when he started and I'm sure it will run well based on his experience. I'm slightly concerned that somebody I know has had his Les/Harris T140 balanced to 81% and was not overly impressed but Andy assures me it will good so I suppose the only way to find out now is to build it and see how it goes.

Fingers crossed :|

Before



After

Strewth !!

Is that I hole plugged on one side, looks like they started drilling on the wrong side and had to fill the hole back in, was it there before or did Basset plug the hole.

Hi Kommando, the hole that you are referring to is, and I quote from the invoice; "1 x 1/2" of tungsten to achieve balance." As I'm sure you will know, tungsten is very heavy.

As I have already said, I'm yet to ride this bike and wonder, based on the amount of drilling that's occurred either how bad was it prior to my ownership, or how bad will it be based on the amount of metal removed? :lol: :lol: I know somebody else who bought a Les Harris Bonneville at the end of last year, and he says it's smoother than his Moto Guzzi......but maybe Basset Down had already balanced that one :lol:

A couple of years ago there were complaints about balancing from Basset, one was on the A10 forum and another on the b50.org forum. Seems the expert balancer left and set up shop himself, after 2 years you would hope they are back up to speed.

Come on Martin, hurry up and nail it back together, we're all dying to see how this pans out...!

Fast Eddie wrote;

Come on Martin, hurry up and nail it back together, we're all dying to see how this pans out...!

Click to expand...

I had some problems with the main bearings which hasn't hastened things. The C2 drive side and CN timing three piece didn't fit as in, the inners wouldn't run in the outers when the outers were fitted. So I've gone CN drive side and still had to take approx 0.0004" more off the outer bearing to get the inner to fit satisfactorily, by fitting it in the lathe and dressing with 120 grit the outside for 5 minutes at a time, refit remove and try again. I did this four times until the inner clunked all the way into it's outer. A C3 bearing sorted the timing side.

Tonight I'm just checking the valve timing and have just made a bracket to sit my dial gauge holder on as they won't attach to the barrels as they are all alloy.

I'm going as fast as I can.......honest ! The gearbox is built

Anyway, how's your Norton coming on? Has the head arrived back at Blighty yet?

Kommando wrote;

A couple of years ago there were complaints about balancing from Basset,

Click to expand...

That's quite disappointing to hear, as I was talking to a longstanding dealer in the south of England prior to sending my crank to B/Down, who wasn't overly impressed with his (Les Harris T140) crank balancing done at Basset Down and described his crank as looking like Swiss cheese.....so a bit like mine and not any smoother, but as I'd had my Moto Guzzi crank balanced there three years ago and that is so smooth you can hardly feel the engine running, I thought I'd give them the benefit of the doubt but now I'm beginning to wonder if it was a good decision?

As I said, I'll know when I get it running.

Head hasn't landed yet Martin but its on its way. Barrels now being bored to suit the new pistons. I'm then gonna get them carbide impregnated.

Am just contemplating stripping the bottom end whilst its down this far, just to have a look... and possibly fit a lightweight Maney crank...

When I was at Steve's premises in January, there were some of his crankshafts on a shelf looking very alluring. I would've bought one myself before now if I didn't want to keep the electric leg that mine has. I asked him if he would, or had ever had considered making a left hand side crank cheek for the mk3 but he doesn't want to make them.......shame!

After a Maney crank on yours, that just leaves a TTI gearbox. Then you can let me know if a TTI is worth it :lol: :lol: :lol: