Houston ....we have a problem ...

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Chris in Margate
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Mon Jun 11, 2018 11:01 am

Bristol Mod is absolutely correct. Take it from me; we're both pensioners and have been here since Noah and Innocenti.
Enlarge a hole in the manifold thus allowing you to pivot it away. Trust me; it works.

johnny650
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Mon Jun 11, 2018 12:27 pm

]OK......
thank you everyone for your patience, information and suggestions .

I have now had the opportunity to measure all the dimensions of the 3x engines that I have and have finally worked out what the problem is. It is the 200cc barrel or more accurately it is the inaccuracy of the bored and tapped holes for the inlet manifold which on my barrel are about 5mm closer to the engine mount than a cast iron OEM 150 barrel....

As Bristle says....... the LiS crankcase uses the late style engine mount with the long bolt .
The diameter is the same diameter as a standard series 3 mount 70mm except S3 TV and LiS were painted white .
Neither have 3x holes but are listed as 'silent mount' by many sellers
.
GP and later mounts have 3x holes and are also erroneously called 'silent mount' which is a bit confusing as I thought it was the holes that created the cushioning effect .

So my options now are
1. extend the manifold length
2. fit offset cones
3. fit a different carb
4. modify the inlet manifold by welding/brazing
4. fit a different engine

The aluminium barrel is a very crude casting with barely sufficient depth of thread insertion for the inlet and exhaust .
Due to the crude porting there is insufficient material left around the ports to drill the inlet manifold and swivel it to gain sufficient clearance for the carb.

If anyone is considering buying an Indian small block kit all I can say based on my experience is DON'T
The supplied cylinder head is a standard 175cc head with no clearance for a 200cc piston. The porting on this barrel must have been carried out by a blind man with a grinder , it is appallingly poor and the manifolds barely cover the edge of the ports.
None of the ports have been deburred within the barrel which would wreck a piston in minutes but I guess that would be something you'd need to do on any after-market barrel. Just don't go there ;)

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HxPaul
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Mon Jun 11, 2018 2:28 pm

These are the standard Li silent blocks.Used on standard series 3 and all series 2 models Li 125/150.They measure 35mm in diameter.https://www.ebay.co.uk/itm/Lambretta-Li ... Sw7GNar2cK
And these are the silent blocks that are used on the rest of the series 3 motors.They measure 50mm in diameter.
https://www.ebay.co.uk/itm/Lambretta-ca ... Sw~AVYwBbC

johnny650
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Mon Jun 11, 2018 2:35 pm

Chris in Margate wrote:
Mon Jun 11, 2018 11:01 am
Bristol Mod is absolutely correct. Take it from me; we're both pensioners and have been here since Noah and Innocenti.
Enlarge a hole in the manifold thus allowing you to pivot it away. Trust me; it works.
Chris I didn't doubt for one moment what BM said and I don't know what I have written in this thread that makes you think so ??
...I just haven't had the opportunity to respond to his last post until this morning. ;) ;)

I am also a pensioner and probably as old if not older than both of you. I had my first Li150 series 2 & series 3 in 1966 . Age has nothing to do with anything in my experience . I've spent 52 years restoring and repairing cars bikes and scoots often rectifying other peoples bodging and mistakes.

Sometimes it is not possible to convey precisely what you wish to in a few words on a forum and everything that is said is often misinterpreted by some who jump too readily to their own conclusions and don't bother to read a whole thread or ask relevant questions to ascertain all the facts and for clarification.

The clearance problem in this case is due to a combination of inaccurately drilled and tapped inlet threads and an over large inlet port in the barrel which didn't occur to me immediately..... hence the question about diameter of engine mounts.

johnny650
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Mon Jun 11, 2018 2:54 pm

HxPaul wrote:
Mon Jun 11, 2018 2:28 pm
These are the standard Li silent blocks.Used on standard series 3 and all series 2 models Li 125/150.They measure 35mm in diameter.https://www.ebay.co.uk/itm/Lambretta-Li ... Sw7GNar2cK
And these are the silent blocks that are used on the rest of the series 3 motors.They measure 50mm in diameter.
https://www.ebay.co.uk/itm/Lambretta-ca ... Sw~AVYwBbC
yes of course ...thank you Paul that should read 50mm not 70mm :roll: I must have hit the wrong key and not noticed ..... groan........ :oops:
I measured them this morning and both my LiS150 and the late series 3 are identical 50mm diameter mounts.

However I have to disagree with you about the rest of the series 3 cases using the 3x hole 50mm mounts though because I thought the 3x hole mounts were only available later than 1964 .

If you study the mounts on my 64 special you will see that although they are the 50mm series 3 white painted mounts they are non 3x hole mounts . As far as I am aware fitted exclusively on the early series 3 TV175 and the LiS150

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HxPaul
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Mon Jun 11, 2018 3:01 pm

I'm not concerned with the ammount of holes.These links are just an example of the sizes.

bristolmod
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Mon Jun 11, 2018 4:03 pm

HxPaul wrote:
Mon Jun 11, 2018 3:01 pm
I'm not concerned with the ammount of holes.These links are just an example of the sizes.
well I am .......but it does depend what sort of night club I'm in and how much I've had to drink......
Scootering since 1968.

bristolmod
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Mon Jun 11, 2018 4:21 pm

"I have now had the opportunity to measure all the dimensions of the 3x engines that I have and have finally worked out what the problem is. It is the 200cc barrel or more accurately it is the inaccuracy of the bored and tapped holes for the inlet manifold which on my barrel are about 5mm closer to the engine mount than a cast iron OEM 150 barrel.."

Are you possibly trying to fix a "150" inlet to a "200" inlet manifold stud spacing? The two inlets have different stud spacing dependant on original cc- the "150" type studs are closer together than "200" type.
Scootering since 1968.

johnny650
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Sun Jun 17, 2018 12:01 am

bristolmod wrote:
Mon Jun 11, 2018 4:21 pm


Are you possibly trying to fix a "150" inlet to a "200" inlet manifold stud spacing? The two inlets have different stud spacing dependant on original cc- the "150" type studs are closer together than "200" type.
not sure what you are talking about now ................

You cannot fit a small block inlet manifold to a big block cylinder nor can you fit a 200cc big block barrel to a small block crankcase unless the crankcase has been modified. ???

If you had read my posts you'll see that I have fitted a 200cc small block engine kit to a Li150 small block crankcase and the inlet that I have fitted therefore has to be a small block inlet doesn't it :roll:

Anyway I have posted the source of the problem and the various options available to me to resolve it ..........so this thread is now closed as far as I am concerned .

bristolmod
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Wed Jun 20, 2018 4:38 pm

johnny650 wrote:
Sun Jun 17, 2018 12:01 am
bristolmod wrote:
Mon Jun 11, 2018 4:21 pm


Are you possibly trying to fix a "150" inlet to a "200" inlet manifold stud spacing? The two inlets have different stud spacing dependant on original cc- the "150" type studs are closer together than "200" type.
not sure what you are talking about now ................

You cannot fit a small block inlet manifold to a big block cylinder nor can you fit a 200cc big block barrel to a small block crankcase unless the crankcase has been modified. ???

If you had read my posts you'll see that I have fitted a 200cc small block engine kit to a Li150 small block crankcase and the inlet that I have fitted therefore has to be a small block inlet doesn't it :roll:

Anyway I have posted the source of the problem and the various options available to me to resolve it ..........so this thread is now closed as far as I am concerned .
well I'm glad we could all collectively help you.....
Scootering since 1968.

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