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Beginner question on le mans 1 engine and frame

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Mingh View Drop Down
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    Posted: 10 Feb 2019 at 17:21
Hi all, 
Apart from specific engine and frame numbers, what are the differences between a stock 850 t3 and a lemans engine? Different crank, pistons, cams? 

Frame wise i was told that the dimensions of a standard t3 frame is the same. Is this correct?
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Ianboydsnr Quote  Post ReplyReply Direct Link To This Post Posted: 10 Feb 2019 at 18:02
pistons, camshaft, valves, heads, as far as I know. Frame is nearly the same, most of the models of the time used the same frame, some used a different bottom rail, with sidestand, the bottom rail is bolt on.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mingh Quote  Post ReplyReply Direct Link To This Post Posted: 10 Feb 2019 at 21:45
Thanks.
So how do i recognize legitimate LM parts from the regulars? Any external clues or does it mean opening up and checking everything?

Jan.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ReggieV Quote  Post ReplyReply Direct Link To This Post Posted: 10 Feb 2019 at 21:48
Engine wise, higher compression pistons, different cylinder heads including bigger inlet and exhaust valves with different (wider) inlet tracts, 36mm Dellorto PHF carbs as opposed to 30mm Dellorto's, 3,300 gr flywheel as opposed to 4250 gr and different variation of the distributor (slightly different advance curve).
 
The camshaft, crankshaft, bearings gearbox, final drive etc are the same.
 
Hope this helps.


Edited by ReggieV - 10 Feb 2019 at 21:53
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ReggieV Quote  Post ReplyReply Direct Link To This Post Posted: 10 Feb 2019 at 22:02
The cylinder heads should have 3 x 6mm mounting allen bolts where the inlet manifolds mount on an LM1 and LM2, whereas the T3 etc had 3 x 8mm mounting allen bolts.
The carbs can be seen. The flywheel would need checking visually and the distributor would need checking for it's number which would have stamped on its base, "S 311 A " as opposed to "S 311 B" on other models. It would be a Marelli.


Edited by ReggieV - 10 Feb 2019 at 22:07
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ken-Guzzibear Quote  Post ReplyReply Direct Link To This Post Posted: 11 Feb 2019 at 11:47
The inlet mountings on T5 heads are the 6mm ones buddy any of the later bikes fitted with the round carbs will be 6mm however they will mostly be the square cylinders, it is very difficult to tell a Le Mans engine from a "cooking" T3 externally Just as a basic bike can be made to look exactly like a T3 California ......in fact not too long ago a bike paper ran pictures of what looked like a T3 Cali the tester remarked how much go it seemed to have and the top end. A look at the photo's showed why there were tell tales that it was in fact a V1000 G5 with a Cali seat and Cali badges on the side panels but lots of clues that it was NO T3 Cali.....Same goes with a Le Mans check frame and engine numbers, owners who have had them some time keep all the paperwork as a rule ...Remember there are more T3 Calis and Le Mans out there than Guzzi actually manufactured!!!
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Mingh View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mingh Quote  Post ReplyReply Direct Link To This Post Posted: 11 Feb 2019 at 21:08
Mine is not a standard bike and it was never sold as a genuine lm. I didn't pay the sticker price either. But i am very curious and am interested to understand how much work it would take to bring it close to the true lm riding experience. But tooling flywheels and rummaging with advace curves aren't the sort of stuff i'll start doing myself.

Story on the genuine lm numbers sounds very much like Laverda Jotas. On the outside there are more slater jotas than regular 3cl laverdas . But you need to go as deep as pistons to really know what you got. Even worse with sfc replicas.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Chris950s Quote  Post ReplyReply Direct Link To This Post Posted: 12 Feb 2019 at 10:18
It has always been thus with Guzzis as  parts from most models are interchangeable. My bike started off as an 850T and now looks like a 750s. 
Chris and Karen - Essex
2011 Stelvio NTX, 1974 950S (750S replica still in bits), 1966 Triumph T100SS 52 years young this year!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jpc Quote  Post ReplyReply Direct Link To This Post Posted: 12 Feb 2019 at 11:08
Originally posted by Mingh Mingh wrote:

  how much work it would take to bring it close to the true lm riding experience.  

As you've mentioned elsewhere that it's intended for commuter use, and yours is a region of 70 kmh blanket speed limit and wall to wall radar surveillance, I would think a nice T3 might prove better.

In my experience the T3 greatly benefits from the big bore kit and an even lighter flywheel. The big valves, big carbs and high compression of the LM don't do much for the everyday riding experience IMHO.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mike H Quote  Post ReplyReply Direct Link To This Post Posted: 13 Feb 2019 at 19:17
Originally posted by Mingh Mingh wrote:

Thanks.
So how do i recognize legitimate LM parts from the regulars? Any external clues


Just to confirm the above, visually, the big PHF 36mm pumper Dell Orto carbs with NO air filters, just open intake trumpets, should be the most obvious.  AND rubber couplings attaching the carbs to the head. Also the inlet manifolds have a shallower bend in compared to the other models, so the carbs point almost rearwards. And, as said, the Allen screws that hold the intake stubs onto the heads are M6 not M8.

Carbs should also have the right angled crank tops as in the below picture. I.e. the cables exit forwards from levers at the sides, not out the tops of the carbs. These carb tops are now unobtanium of course. Big smile

HTH






Edited by Mike H - 13 Feb 2019 at 19:22
"Chicken nuggets don't dance on a Tuesday."
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Post Options Post Options   Thanks (0) Thanks(0)   Quote GuzziPaul Quote  Post ReplyReply Direct Link To This Post Posted: 14 Feb 2019 at 13:14
The 6mm manifold bolts was always a quick and easy check. The harder bit is telling the difference between a late LM and an early LMII rather than a T3 I would have thought. Especially as the bikes are over 40 years old by now and lots of bits will have been upgraded or replaced. My LM has a different flywheel (lightend) and air filters (I've kept the bellmouths). but I've kept the original switchgear on as I reckon if you were doining a homarge you would bother spending £400 on crappy switchgear when you could spend a lot less to "upgrade" even on a MKII.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Chris950s Quote  Post ReplyReply Direct Link To This Post Posted: 14 Feb 2019 at 16:36
Originally posted by Mike H Mike H wrote:

Originally posted by Mingh Mingh wrote:

Thanks.
So how do i recognize legitimate LM parts from the regulars? Any external clues
. These carb tops are now unobtanium of course. Big smile
Eurocarbs list these carb tops.
Chris and Karen - Essex
2011 Stelvio NTX, 1974 950S (750S replica still in bits), 1966 Triumph T100SS 52 years young this year!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote TheWrongTrousers Quote  Post ReplyReply Direct Link To This Post Posted: 14 Feb 2019 at 19:05
I would not be surprised if Ducati Paddy did them too. He has all sorts - like an aladdin cave it is.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mike H Quote  Post ReplyReply Direct Link To This Post Posted: 14 Feb 2019 at 23:20
Originally posted by Chris950s Chris950s wrote:

Originally posted by Mike H Mike H wrote:

Originally posted by Mingh Mingh wrote:

Thanks.
So how do i recognize legitimate LM parts from the regulars? Any external clues
. These carb tops are now unobtanium of course. Big smile
Eurocarbs list these carb tops.


Not according to their page here. I did look before I posted. That's also where the drawing came from. Big smile

https://www.dellorto.co.uk/shop/dellorto-motorcycle-carburettors-parts/carburettor-parts/phf-parts/phf-top-casting-lower-discontinued/

Those are for Laverda, 8820 "discontinued", 8822 "phone us for stock check"

"NO LONGER AVAILABLE For the PHF36BS Independently cable operated variations we no longer have the lower castings."

Which I believe is the variation LM's use.

All  search results for “phf 36” -

https://www.dellorto.co.uk/?s=phf+36&post_type=product

No sign of the top covers that go on the RA pull carb tops either. Ouch


"Chicken nuggets don't dance on a Tuesday."
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