S1 li125 engine upgrades

[Livi- Graeme]

My brother has a early s1 li125engine. The one with the petrol lubrication of the flywheel crank bearing. What upgrades can be done if any to increase performance a little. Will a 150 top end fit. Will it have to be a s1 150 top end ? Cheers Graeme

[kevspeed]

Personally i would change the crank/bearings/mag housing for the later items,purely for the reliability side of things!,a 150 or a 175 cc barrel/piston/head will fit straight on with no problems (providing you use a 175 'conversion' piston if you choose that size,as the original TV piston uses a different con rod length),then upjet your carb to suit!

[Livi- Graeme]

Thanks for the reply. To clarify are you saying that a s3 mag housing will fit allowing me to fit a gp crank and therefore whatever top end I wish. Orr have I got the wrong end of the stick.graeme

[bristolmod]

you will also need the correct Head Cowling as well- the S1 one is shorter.

Chris

[kevspeed]

Thanks for the reply. To clarify are you saying that a s3 mag housing will fit allowing me to fit a gp crank and therefore whatever top end I wish. Orr have I got the wrong end of the stick.graeme

Yes,a series 3/GP mag housing will fit,along with a GP crankshaft,and any series 1/2/3/GP 125/150/175 top end,but as Bristolmod said,you will need a different head cowling,as the series 1 type are shorter

[Livi- Graeme]

Perfect. Means I can put 12volt electrics as well cheers for the info. Graeme