Areas of highest risk of piston seizing in Lambretta

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e_9111
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Sun Mar 28, 2010 10:34 pm

Hello friends, On frist moment I like ask Sorrys for me bad enghlis ,SORRY SORRY
I like open this link for konw your opinion.
Have 1 old piston Tarabusi on 3 seizing-points,,,,2 near windows-exit and 1 near windows admision
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On this other photo (piston 70,2 segmets ASSO) I paint 3 areas,,,areas where runing the piston near wall of cilinder.
I like make a hold small on the wall of piston,,,,on this mode this cilinder-area or piston-area is "good-refrigerated" and "good-lubricated",,,on this mode I think,,,,have minus options for seizing.

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This smalls holes no need be more big,,,smalls and no can exit from the line of moviment.
This moviment-line is paint on this 2 photos following.
I like konw your opinion
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== Enrique ==
RapidoRace 225

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Supereibar
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Mon Mar 29, 2010 9:13 am

Enrique, if you need help to translate anything please let me know mate...

Regards,

J.

P.S: I think people might have some trouble understanding what you are trying to deliver here. We had trouble understanding you in the Spanish forum. Possibly explaining to me over there then me translating here? Might work?

J1MS
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Mon Mar 29, 2010 3:57 pm

It seems the hot spots on the piston line up with the cylinder studs. The small drillings that are to be made in the piston are to add lubrication & cooling to these points???

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RinB
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Mon Mar 29, 2010 5:19 pm

Hi Enrique

What you show is very good and is very common to have siezures on the stud line.

Drilling holes in the piston at these point will help lubricate.

But first the Rapido barrel you have with the Asso piston may need attention

1. check bore to piston clearences as some times this can be quite small as low as 1.5thou of an inch.
Id suggest get it honed out to 3-3.5thou of an inch.

2. Make sure all Ports have an angled chamfer on all the edges especialy Transfers and Exhaust.

3. make sure Head has correct combustion chamber size to give 9-9.5 Compression ratio

These kits can give you miles of trouble free scootering


Regards m8

Smiffy
If its made of Metal Fettle it !!

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e_9111
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Mon Mar 29, 2010 8:05 pm

"J1MS",,,, this area yes agree, I look now this,,and the area big also agree :o :o :o
is for "inspected" slowly this date
For this 3 points "Smiffy" I go follow religiously, the piston old is of the lambretta lince from Madrid,,,now is on Valencia on me house and is on process of inspection total,,,,
The piston of 70 mm is for me Rapido-Kit 225, and me idea is check this 3 points you say me,,,and also put
for every corridor where can exit this "seizing " 1 hole small on the piston
-corridor of 15mm put (on the piston) a hole of 5 mm to center lines
-corridor of 20mm put a hole of 10 mm or two of 4 mm
Or put a big X whit the dremell on the piston ,,,X of 5mm without perforating the piston,on this mode have a area whit Oil and gasoline mix,,,this can make similar funtion
What opinion have ???? Regards
== Enrique ==
RapidoRace 225

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RinB
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Mon Mar 29, 2010 9:21 pm

e_9111 wrote:"J1MS",,,, this area yes agree, I look now this,,and the area big also agree :o :o :o
is for "inspected" slowly this date
For this 3 points "Smiffy" I go follow religiously, the piston old is of the lambretta lince from Madrid,,,now is on Valencia on me house and is on process of inspection total,,,,
The piston of 70 mm is for me Rapido-Kit 225, and me idea is check this 3 points you say me,,,and also put
for every corridor where can exit this "seizing " 1 hole small on the piston
-corridor of 15mm put (on the piston) a hole of 5 mm to center lines
-corridor of 20mm put a hole of 10 mm or two of 4 mm
Or put a big X whit the dremell on the piston ,,,X of 5mm without perforating the piston,on this mode have a area whit Oil and gasoline mix,,,this can make similar funtion
What opinion have ???? Regards
Enrique
you shouldnt need to put holes in the piston like you suggest if the clearance are correct.
Certainly not the size you are suggesting, Only really need 1-2 mm
If you feel you need to do something then the X inprint on piston may help


Smiffy
If its made of Metal Fettle it !!

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oldbiker
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Mon Mar 29, 2010 9:43 pm

J1MS wrote:It seems the hot spots on the piston line up with the cylinder studs. The small drillings that are to be made in the piston are to add lubrication & cooling to these points???
On some TZ`s and TDR`s these holes line up with the part of the barrel between transferes and exhaust port. the holes are 1.5 mm in dia.

J1MS
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Mon Mar 29, 2010 9:49 pm

tzr.steve wrote:
J1MS wrote:It seems the hot spots on the piston line up with the cylinder studs. The small drillings that are to be made in the piston are to add lubrication & cooling to these points???
On some TZ`s and TDR`s these holes line up with the part of the barrel between transferes and exhaust port. the holes are 1.5 mm in dia.
I think Smiffy already has the right approach to this with the bore clearance, sort this and the Cylinderhead then maybe the piston mods wont be needed, but 1.5mm holes with an X cut through it would pretty much lube anything thats needed..

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e_9111
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Tue Mar 30, 2010 7:35 am

Oky,,,Here now all we are entry "on heat" whit this this topic of holes
I paint 3 areas,,,A,B and C whit yours mm , the line red is the moviment of this holes make on piston
for me,,,1,5mm is good on diameter,,and how "Worldwide" see correct put this "X",,,now comes "the Tema", ¿How many mm need be the X for area A or B ? and for the area C ? and thickness and depth ??
This tema no end here,,,jejejejee now is very important to maintain a safe distance with each zone boundary lines
Thanks worldwide for suport me,,,,
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== Enrique ==
RapidoRace 225

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