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Knowledge wrote:Dickie,
I was not aware that the 125 Special was noticeably different in performance than a standard 125. Thanks for the pointer. How do I spot the difference?
The carb is already 20mm.
Mick,
So you are suggesting that I blueprint the engine? Now that is a pretty sensible idea.
Perhaps I should combine these ideas from Mick and Dickie.
lofty wrote:If i remember rightly LI 125 had tiny transfers anyway..
centre squish head (gp125?) no head gasket, open ports to match manifolds..
and enjoy the scenery..
otherwise, get an autisa barrel & 54 crank
Warkton Tornado No.1 wrote:lofty wrote:If i remember rightly LI 125 had tiny transfers anyway..
centre squish head (gp125?) no head gasket, open ports to match manifolds..
and enjoy the scenery..
otherwise, get an autisa barrel & 54 crank
Did Autisa make a small bore barrel with the stud fixings for a small block? I am aware of the '125 conversion' alloy, large fin spacings for large block cases as I have one that somebody had altered for a reed valve inlet & intended fitting the liners that came with it. I rather wish it had not been altered, as the quality looks to have been spot on......
Just to add my two penny worth, if the scooter in question was owned by somebody I knew, I would see how they fare, & then, when they can 'cope' with all of that power they had(!) & gnashing @ the teeth for more, embark on an engine build with another case with components determined by budget, scope of 'project' & rider ability.
We are all guilty of having pre-conceived ideas when it comes to Lambretta modifications, but the truth is, I have seen many riders with a riding ability that borders on incompetent. It's always a good test to look @ the tyres of anybody that claims to be a 'hot' rider.
Just sayin'.....
Warkton Tornado No.1 wrote:lofty wrote:.... otherwise, get an autisa barrel & 54 crank
Did Autisa make a small bore barrel with the stud fixings for a small block?
Knowledge wrote:[I can work the squish on my new lathe and improve the flow of the ports following DT’s principles and see where I get to.
Knowledge wrote:Thanks Colin.
I did watch Dan’s “wasted tuning” video on YouTube and I did bear that in mind when starting my thoughts about the 125. Thank-you for highlighting it here.
It is well worth the watch (if a tad too long) if anyone hasn’t seen it.
I might pop up to see you with the engine and try your barrel on and measure it with the Buzzwangle.
Knowledge wrote:Warkton Tornado No.1 wrote:lofty wrote:.... otherwise, get an autisa barrel & 54 crank
Did Autisa make a small bore barrel with the stud fixings for a small block?
Yes, Autisa did make an alloy barrel that worked with a 200 casing and a 54mm crank, but due to their rarity , I thought it best to stick with the standard 52x58 configuration. If someone wants to start a separate thread about that kit, please do and I will contribute.
WT1,your other comments are valid, but I was assuming that the standard kit made 5.5bhp, so tuning it to hit a mighty 7.5bhp should not scare the new owner too much. However, that was before I learnt that the later 125 iron barrels made around 7bhp already.
Anyway, I have learnt that the engine concerned may have a GP125 barrel already. I can work the squish on my new lathe and improve the flow of the ports following DT’s principles and see where I get to. The crank is GP and the carb is SH20. I would like to keep the original exhaust, though I am not averse to altering it. I have no idea about the gearbox, but I hope to get my hands on it by the weekend.
Any more thoughts guys?
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