Steel flywheels

Information relating to the Matchless G2 or AJS Model 14 250cc Lightweight
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Roderick
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Steel flywheels

Post by Roderick »

I wonder is it possible to use 350 (G5/Model 8) steel flywheels in a 250 cc Lightweight engine rebuild? The part Nos. are different for the 250 & 350 L/W steel flywheels. Is the balance factor different or something else? Has anyone tried it?

Rod
John Jarrett
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Re: Steel flywheels

Post by John Jarrett »

The stroke is different so you will have problems using them in a 250... the piston will pop out of the top of the 250 barrel. Hence the reason that the 350 barrel in taller than the 250.
Roderick
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Re: Steel flywheels

Post by Roderick »

I was hoping you could use a 250 conrod assuming the 350 bigend is the same as in the later 250 engine.
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clanger9
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Re: Steel flywheels

Post by clanger9 »

Nope, stroke is much longer: 85.5mm (350) versus 64.84mm (250).
1989 Moto Morini Dart 350
1993 Ducati 750SS
Roderick
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Re: Steel flywheels

Post by Roderick »

OK, thanks folks.

Rod
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spitfire
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Re: Steel flywheels

Post by spitfire »

You can use the 250 conrod on 350 flywheels the big end in the 350 is the same as the csr 250.
The 350 has a longer conrod to get the extra stroke plus a taller barrel
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clive
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Re: Steel flywheels

Post by clive »

spitfire wrote: Sun Oct 31, 2021 4:51 pm You can use the 250 conrod on 350 flywheels the big end in the 350 is the same as the csr 250.
The 350 has a longer conrod to get the extra stroke plus a taller barrel
I struggle to get my head around these sorts of issues but is the length of the stroke not determined by where the big end is placed in the flywheel rather than the length of the conrod? If you fitted a shorter conrod (21mm?) would you not have a problem with the skirt of the piston hitting the flywheels at bottom dead centre?
clive
if it ain't broke don't fix
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spitfire
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Re: Steel flywheels

Post by spitfire »

The pistons are alsp different, the 250 pistons do run very close to the flywheels
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