Great vid Mark had a purple one myself I raced mine up didn't have an expansion chamber but it did fly 65 down hill went to Southend and back Reg Number HLA 62N don't know if it still going amazing machine
How in hell those engines managed to take all of the tune-up tweaks etc to get a few more HP without exploding is a testament to how well Japanese 2-strokes were built.Brilliant fun
The mod that real does the most to increase power after all the usual porting, jetting up blueprinting etc is to remove a certain amount off the trailing edge of the fibre disc valve. easy job and gets more fuel charge into the combustion chamber. it ups the rev range and compliments the raised exhaust port mod. 55-60+ mph is certainly possible then. use only the very best synthetic racing two stroke oil. actually with one "experiment" my friend did back in the day was such extreme exhaust/disc valve mods were tried that the bike was revving to 15000+ rpm that with its small cast iron barrel it was overheating and seizing so he tried "Castrol R" Racing mineral oil and vollia. no more seizing.
Castrol R - either R30 (recall buying this many years ago) or R40 - is Castor-based. It does tend to help “marginal” or highly stressed engines last, though. Needs substantial and frequent maintenance to deal with the carbon and gum. R30 tends to be hard to find. R40 tends to be a bit more available in much of the world.
Class whatever you had - I had a Fantic SuperT - went well....then, at 17, I went and got an RD250 Air-cooled - expansion pipes, Silver with Red stripes - doing the most mental things on it - only knew one position for the throttle - I wonder to myself 'what do the poor young f__ks have today????' cos I think they've got nothing apart from mobile phones, electric scooters and Mandbags .....it really is pretty sad - you have to feel for them - they'll be nothing and they'll have done nothing and you can't just say "it'll work itself out" as my Dad said and it did ... cos it won't
