I’ve got my eye on a Mk2 Le Mans. The long term owner replaced the cylinder heads and pistons with those from an 850 T3 to lower the compression and enable the bike to run on unleaded fuel. As a result it has T3 performance not Le Mans performance. He still has the original cylinder heads and pistons, what would be the implications of re-installing these? What other work would be required to enable the bike to run on unleaded?
watching with interest. Curious to learn what there might be in a LM2 head that prevents it from running on lead-free, as is (was) standard. I shan’t even mention running on good stuff vs. not so good stuff (o;
Hope an expert arrives soon.
is he going to include the pistons and heads in with the price, or try to sell them for more money ?
also the rings from the origional pistons, were they swapped over to the new pistons to match the bores
or did he change the barrels as well ?
all seems very odd to me
it is not a big job to have hardened valve seats installed in the LM heads, , new valves and springs at the same time are a good idea
as the T3 was produced at the same time, then unless the heads have been modified, it was not designed to run on unleaded fuel but has a lower compression ratio of 9.5;1 against the LM2 of 10.2;1
‘ is he going to include the pistons and heads in with the price, or try to sell them for more money ?’
- They would need to be part of the deal
‘also the rings from the origional pistons, were they swapped over to the new pistons to match the bores
or did he change the barrels as well ? ‘
- Can’t answer the ring question at the moment
, but the barrels are original LMs2 with cast iron liners.
‘all seems very odd to me’
- a few things to be bottomed out with the seller and the cost of putting the bike into original shape to be factored into any deal. Thanks for the input.
it might be worth checking the chassis and engine numbers as well, to make sure its the real deal
cant recall them off hand, but I think the frame numbers dictate the model, just in case its a Bitza ie a T3 converted
engine numbers do not run concurrent with frame number though but should have the same prefix
frame number should be in inside of this batch ( 1978 to 1980 )
VE 13041 to VE 24086
A series 111 Le Mans starts with VF
An 850 T starts with VC
A T3 to T4 starts with VD
A T5 starts with VR
from memory it should have a small fairing and leg shields , front brake calipers behind the fork legs,
also check the registration book, to make sure frame and engine numbers tally, the old Oh sorry I forgot to update cuts no ice with me, a good clue is how long the seller has owned the machine, and ridden it, lots of old MOTs and service paperwork and parts records, too short a history and he might be a wheeler dealer
they are getting to be silly money these days, so it pays to be careful
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Never heard such nonsense, I had a mk1 lemans back in the day which ran on 5 star, when that became difficult to get the bike started pinking, backed the timing off a couple degrees and it was fine. Still have a mk1 and run it on unleaded but try to put minimal ethanol when I can.
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Oh and what carbs are on it. If it’s the t3 type then I think it’s probably a T3 as a previous poster alluded to
you have never heard such nonsense ?
thank you for your kind words, but coming from a family of engineers, and owning a driving a classic car, I do have some experience of valve seat recession, if you are a sunday Poseur and do the odd ride out to meets, you are unlikely to suffer from valve seat recession for a small while due to lead memory, but it will cause the valve clearances to tighten up
any way I cant be bothered with slanging matches with know it alls, so I will not be returning to this forum, same reason I gave up with the face book one
Rapheal is right regarding the valve seats…I thought the guides had to be changed as well, owing to the lack of lubricity of unleaded fuels.
IIRC, this was quite a hot topic at the time that lead additives were being phased out.
Or am I imagining that?
The nonsense part was not directed at you, it was the sellers reason for allegedly turning a Le Mans into a T3. Apologies if you have been upset.
The problem with all things done electronically is that they can be easily misunderstood.
Looking forward to my Sunday pose 
So. Not to derail this thread (just talk over my head!) - I was thinking about the carbs, and wondering “is this really a LM2, or…?”. Also, I dimly remember the fuss over unleaded and a rush to get heads converted (RaceCo offered a service, I think?), and a receipt in my T3 folder says my heads* were “done”, but then (I also dimly remember, a strong voice from many saying that the valves and seats of regular Guzzis were more than up to the task. But hey, I’m no engineer. And neither can I play the Mandolin, but that’s another story.
Carry on…
- Now irrelevant. I had them changed because… ah I forget. And I replaced the barrels because Chrome… oh! not. What do I do with these shiny Gilardonis now? Meh. Bung them on anyway. Andiamo.