GT 240 Options

Anything related to Lambrettas... ask tech questions, post helpful info, or just read and learn.
MickBH
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Main scooter: Lambretta Series 2
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Leo wrote: Sat Mar 06, 2021 10:34 pm
wintermod65 wrote: Thu Mar 04, 2021 1:45 am
Leo wrote: Wed Mar 03, 2021 11:11 pm I had a CST3 on my GT240 and it was very nice.




didnt you have seizure issues with your GT 240 as well ? did you ever sort it or did you go with another top end

i looked into the underkickstart pipe from chiselspeed for my gt240 but they recommended the cst 7

after a few more setbacks i think il follow dan from scooterings example an go for a TS1 build .

im just wondering on the feasability of using a 65mm crank to give 250cc ive got GT casings im told theyll accept 64mm cranks without additional work so hopefully a 65 will go in . im pretty sure darrell taylor does a 65mm crank after watching the TType engine video on youtube so might have to get some advice regarding this set up.
im wondering whats the biggest cc i could go up too with a 70mm TS1 barrel using any of the currennt big casings and cranks available ?

.pipe wise im looking at a ron moss ex box st as soon as they return to stock at dealers .

as for the GT kit thats destined for ebay when i can get the scooter back from its temporary home for the last 15 months over in worcestershire
I gave up in the end and swapped the top end.
So are you running a different cylinder on the GT 62mm crank?
Leo
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MickBH wrote: Sun Mar 07, 2021 2:20 am
Leo wrote: Sat Mar 06, 2021 10:34 pm
wintermod65 wrote: Thu Mar 04, 2021 1:45 am





didnt you have seizure issues with your GT 240 as well ? did you ever sort it or did you go with another top end

i looked into the underkickstart pipe from chiselspeed for my gt240 but they recommended the cst 7

after a few more setbacks i think il follow dan from scooterings example an go for a TS1 build .

im just wondering on the feasability of using a 65mm crank to give 250cc ive got GT casings im told theyll accept 64mm cranks without additional work so hopefully a 65 will go in . im pretty sure darrell taylor does a 65mm crank after watching the TType engine video on youtube so might have to get some advice regarding this set up.
im wondering whats the biggest cc i could go up too with a 70mm TS1 barrel using any of the currennt big casings and cranks available ?

.pipe wise im looking at a ron moss ex box st as soon as they return to stock at dealers .

as for the GT kit thats destined for ebay when i can get the scooter back from its temporary home for the last 15 months over in worcestershire
I gave up in the end and swapped the top end.
So are you running a different cylinder on the GT 62mm crank?

Yes, I got a Monza 225 for a good price and tuned, set port timings to achieve nice low end power rather than the hi revs they are known for. With the longer stroke I could set the transfer ports low enough and easily fiddle with the exhaust port height until I was happy. I checked the crank for true before I used it with the Monza. Not had much chance to ride it this last year due to Covid etc. but its done maybe 3-400 miles and I like it. Makes similar power (24 hp) to what the GT240 did.
eden
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wintermod65 wrote: Thu Mar 04, 2021 1:45 am
Leo wrote: Wed Mar 03, 2021 11:11 pm I had a CST3 on my GT240 and it was very nice.




didnt you have seizure issues with your GT 240 as well ? did you ever sort it or did you go with another top end

i looked into the underkickstart pipe from chiselspeed for my gt240 but they recommended the cst 7

after a few more setbacks i think il follow dan from scooterings example an go for a TS1 build .

im just wondering on the feasability of using a 65mm crank to give 250cc ive got GT casings im told theyll accept 64mm cranks without additional work so hopefully a 65 will go in . im pretty sure darrell taylor does a 65mm crank after watching the TType engine video on youtube so might have to get some advice regarding this set up.
im wondering whats the biggest cc i could go up too with a 70mm TS1 barrel using any of the currennt big casings and cranks available ?

.pipe wise im looking at a ron moss ex box st as soon as they return to stock at dealers .

as for the GT kit thats destined for ebay when i can get the scooter back from its temporary home for the last 15 months over in worcestershire
A kit sold on ebay not long ago and from the images it had been built using a head gasket, I'm presuming that was your kit?
The 240 is designed to not run with a head gasket, the barrel fits onto a GT casting with a single base gasket and no head gasket which gives 1.25 squish.... if that was yours with the head gasket it's no wonder it never ran well.
I'm interested to hear if it was built with that from new from Dez or if you fitted it later?
wintermod65
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Joined: Mon Apr 02, 2018 8:06 pm
Main scooter: winter model
Location: Suffolk
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[/quote]

A kit sold on ebay not long ago and from the images it had been built using a head gasket, I'm presuming that was your kit?
The 240 is designed to not run with a head gasket, the barrel fits onto a GT casting with a single base gasket and no head gasket which gives 1.25 squish.... if that was yours with the head gasket it's no wonder it never ran well.
I'm interested to hear if it was built with that from new from Dez or if you fitted it later?
[/quote]


It wasnt mine , scooter is still over at dezs waiting for them to get smiths conversion they did to work

once i get it back its going in for a ts1240 to be fitted at another shop so it will be a while yet before my gt kit goes on sale not sure what the one you saw went for but dont suppose thetes much return on 2nd kits even if come with new piston
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