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RB 250 Set Up
Posted: Thu Jul 19, 2012 3:02 pm
by Lamaddict
Gearing - I've already got a standard Li125 gearbox, later type which I'd like to possibily use, just because I've got one in the garage. I can get to 4.6-4.8 with the sprokets but any comments on how it may perform?
Crank - I've already got a 58 SIL webbed 110 Yam rod which I'd like to use with packers to get it all lined up, any comments?
Piston and head - I'm thinking of an MB Racetour piston and cylinder head to suit?
Re: RB 250 Set Up
Posted: Thu Jul 19, 2012 4:00 pm
by Yanker
Lamaddict wrote:
Crank - I've already got a 58 SIL webbed 110 Yam rod which I'd like to use with packers to get it all lined up, any comments?
Piston and head - I'm thinking of an MB Racetour piston and cylinder head to suit?
Hi, the 250 is designed arround 60mm stroke crank. you would need to use the port timing calculator to see if you can get desired/reasonable timings with that crank, using the port heights in the barrel.
The RB 250 piston is forged with 1mm wire rings: therefor the same spec as the MB pistons.
AF do a selection of heads with different compression ratios for this kit.
Re: RB 250 Set Up
Posted: Fri Jul 20, 2012 2:56 pm
by Lamaddict
Yes I'll be knocking the CC's down.
I didn't realise AF offered head options. Thinking back I think MB and AF have had differing views on cylinder heads?
RB 250 Set Up
Posted: Fri Jul 20, 2012 2:58 pm
by jonashford
Afs are testing the Avanti head on the rb at the moment
Re: RB 250 Set Up
Posted: Tue Jul 24, 2012 10:34 pm
by Terrible Taff
Lamaddict wrote:Yes I'll be knocking the CC's down.
I didn't realise AF offered head options. Thinking back I think MB and AF have had differing views on cylinder heads?
At Taffspeed I have used the 10.5 high comp head AF option then machined it so no head gasket is used & dowelled central with the squish 1.5mm recessed into the head.
I have used 5.8 to 1 corrected compression ratio.
This allows for the use of 95 octane unleaded With 4% oil mix to keep the crank lubed.
17' btdc ignition advance, Franspeed JL race exhaust, 34mm Dellorto VHSB.
BR8ES or 240 degree C heat range spark plug this gapped @ 0.020" (0.5mm)
Gearing set for 80mph max sitting upright solo riding so that the scooter performs over a wide speed range.
The RB250's that I have built up are all over 30bhp @ rear wheel 21 ft/lbs torque @ 7,000 rpm.
Hope this info has helped those tuning their RB motors!
Regards
Ian Frankland
Taffspeed
07794 003276