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RB20 fitting problem!!

Posted: Sat Mar 08, 2014 9:53 am
by kevspeed
Helping a mate out,putting together an RB20 engine,anyone had problems fitting this kit??
Problem 1,The barrel wont slide all the way down onto the gasket face,even tried on a different set of cases,it stops about 10mm short.
Problem 2,Cant get the piston into the bore much past the rings.The Piston is marked 65.79,is this correct?
Problem 3,The centre of the 'cassette' clutch doesnt seem to want to fit in its hole,any ideas?
Just thought i would ask here first before contacting the dealer and being told '''we've never heard of this problem before''.

Re: RB20 fitting problem!!

Posted: Sat Mar 08, 2014 10:02 am
by 10 inch Terror
http://scooterotica.org/forum/viewtopic.php?t=28920
This may help with the tight barrel issue.

Re: RB20 fitting problem!!

Posted: Sat Mar 08, 2014 8:10 pm
by kevspeed
Thanks for that,problem sorted,i just have to find out why the piston wont go in the barrel properly!!
This is as far as i can get the piston in!!
Image

Re: RB20 fitting problem!!

Posted: Sat Mar 08, 2014 9:30 pm
by Spanish Fly
kevspeed wrote:i just have to find out why the piston wont go in the barrel properly!!
This is as far as i can get the piston in!!
Will the piston go into the cylinder when unassembled? i.e. just the piston and the cylinder? No rings, no con rod, no crankcase.

SF

Re: RB20 fitting problem!!

Posted: Sun Mar 09, 2014 9:12 pm
by kevspeed
Yep,just way too tight with the rings fitted!,rings on their own,no problem,piston on its own no problem!

Re: RB20 fitting problem!!

Posted: Sun Mar 09, 2014 9:20 pm
by fairspares
have you put the rings in the barrel and checked they have the correct clearance?

http://www.lambrettaspares.com/info/set ... -+163.html

Re: RB20 fitting problem!!

Posted: Mon Mar 10, 2014 12:32 am
by carlos fandango
I've posted on lcgb for you.......
Basically the rings will catch on the fingers of the boost ports

Re: RB20 fitting problem!!

Posted: Mon Mar 10, 2014 9:11 am
by kevspeed
fairspares wrote:have you put the rings in the barrel and checked they have the correct clearance?

http://www.lambrettaspares.com/info/set ... -+163.html
Got to be fair!,that link was a very interesting read,we will be having another go at the RB in the week,with the info in that link taken on board!

Re: RB20 fitting problem!!

Posted: Mon Mar 10, 2014 11:02 pm
by soosh
kevspeed wrote:Thanks for that,problem sorted,i just have to find out why the piston wont go in the barrel properly!!
This is as far as i can get the piston in!!
Image
So the studs were causing the barrel not to slide down fully?

Re: RB20 fitting problem!!

Posted: Tue Mar 11, 2014 8:57 pm
by kevspeed
DONE!!,basically a combination of odd thin/fat studs,and the stud holes catching on the last couple of threads.Ive now drilled out the bottom of the barrel stud holes to 9mm.