rapido race 200
Hi , Darren here from Lambretta club of South Australia ,what sort of HP should i expect out of this tune ,Race Rapido 200 ,all ports matched and polished, 34 mil mikuni carb ,mugello center squish head ,jl4 pipe ,variatronic,24 deg ,li 150 gears
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Knowledge
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There are two castings: the Classic and the Race.
The rapido seems to be a very strange kit, with a number of problems, especially for people wishing to keep within the regulations of British racing. It also has some challenges for the road user as well.
As most racers have now moved onto newer kits for group four racing (that is, piston ported 200cc engines), there aren't many secrets left in the rapido, so I'll spill a few poorly kept secrets.
First, the primary transfers are too close to the exhaust port and can easily short-circuit, meaning that fresh fuel disappears out of the exhaust port without doing any useful work. The "race" spec barrel is, if anything, slightly worse. You need to do a lot of work in very awkward places to get these to flow in the right direction.
The inlet varies in cross sectional area along it's entire length. This affects the the velocity of the incoming charge, which should, in a good engine, be constant. In the rapido, it slows and speeds up. The engine seems very sensitive to inlet timing caused by piston skirt length.
The shape of the exhaust port is upside down, and the studs are offset as a result.
Having said all that, some tuners have got around 30bhp out of a race engine, but I'm not sure that you should be looking at attaining these heady figures. The barrel is better for creating an engine of about 18bhp for road use, and given a choice, I'd start from a Rapido classic barrel.
Try JB Tuning at Southend. He's put a lot of development into Rapido barrels and he can help you.
The rapido seems to be a very strange kit, with a number of problems, especially for people wishing to keep within the regulations of British racing. It also has some challenges for the road user as well.
As most racers have now moved onto newer kits for group four racing (that is, piston ported 200cc engines), there aren't many secrets left in the rapido, so I'll spill a few poorly kept secrets.
First, the primary transfers are too close to the exhaust port and can easily short-circuit, meaning that fresh fuel disappears out of the exhaust port without doing any useful work. The "race" spec barrel is, if anything, slightly worse. You need to do a lot of work in very awkward places to get these to flow in the right direction.
The inlet varies in cross sectional area along it's entire length. This affects the the velocity of the incoming charge, which should, in a good engine, be constant. In the rapido, it slows and speeds up. The engine seems very sensitive to inlet timing caused by piston skirt length.
The shape of the exhaust port is upside down, and the studs are offset as a result.
Having said all that, some tuners have got around 30bhp out of a race engine, but I'm not sure that you should be looking at attaining these heady figures. The barrel is better for creating an engine of about 18bhp for road use, and given a choice, I'd start from a Rapido classic barrel.
Try JB Tuning at Southend. He's put a lot of development into Rapido barrels and he can help you.
Martin
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paulmgreen
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- Main scooter: Lambretta Group 4 Race 200
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You could also try Chalky White at Replay in Rothwell.
He has done the barrel work on my race engine - using a Rapido....
Here is Dyno Chart 31.5 HP
He has done the barrel work on my race engine - using a Rapido....
Here is Dyno Chart 31.5 HP
YouTuve Vlog channel - https://www.youtube.com/channel/UCEhrgL ... vY_4Px2WTg
www.JPPLambretta.co.uk
Sponsors Replay Scooters JPPLambretta
www.JPPLambretta.co.uk
Sponsors Replay Scooters JPPLambretta
Darren here from lambretta Club of South Australia,I have always tuned my own cylinders ,jap piston conversions etc,I always intended to use a suzi pe 250 piston and ape rod with this kit but ended up using it as it is ,the more i mess with it [ports] the better it gets ,i am getting very concerned about the asso piston ,this kit pulls very very well through the gears[its as fast as my stage 6 230] when it hits 60 mph it pulls like f k to 80 mph ,i have changed transfer angle in cylinder and it runs better ,problem is nobody seems to be doing this sort of thing over here ,[just bolt on kits] but i do know it is faster than a ts1 225 in a straight line ,i am still undecided wether to fit a 60 stroke crank ,[regarding other post kit is race 200 not 225 ] cheers .
RAP 200 wrote:Darren here from lambretta Club of South Australia,I have always tuned my own cylinders ,jap piston conversions etc,I always intended to use a suzi pe 250 piston and ape rod with this kit but ended up using it as it is ,the more i mess with it [ports] the better it gets ,i am getting very concerned about the asso piston ,this kit pulls very very well through the gears[its as fast as my stage 6 230] when it hits 60 mph it pulls like f k to 80 mph ,i have changed transfer angle in cylinder and it runs better ,problem is nobody seems to be doing this sort of thing over here ,[just bolt on kits] but i do know it is faster than a ts1 225 in a straight line ,i am still undecided wether to fit a 60 stroke crank ,[regarding other post kit is race 200 not 225 ] cheers .
Hi Darren.
can you please explain what kind of tune you have done to the barrel ?? which transfere angles have you changed and how much ?? have you some pics of the barrel ??
fishi