Engine tuning under development

 

 

Dave's RB250 Sprinter

AF-Rayspeed has kindly sold us one of there machined wrong RB250cc kits to play with next season. This will be based on the origanal layout but with iron liner and different piston and conrod length. Different port layout with wider sub exhaust ports.

We are also thinking of setting this scooter to do top speed days alongside another project we have in mind.

 

Speck is as follows-

Piston 98 gram lighter than rapido/rb 250.Dome 2mm lower with 16mm gudgeon pin.

60mm crank fitted with rd350 con rod and 18 big end rollers and welded pin.

New iron liner with 1mm top sprigot for location of head.

Alloy billit centre plug head.

38mm mikuni carb

SES RB Teaser exhaust

 

Petes GP200 Road Scooter

Pete's lambretta was used back in August 2007 for a little play. He brought the gp as per Indian stage 4 standard and for a bet he took it to Santa Pod in 2007 and achieved 53mph at 22.5 seconds. After that he wanted a little more speed but did not want to spend a lot of money. A year later it is achieving 15.98 seconds at 83 mph and is still used daily for work, plus rally going and sprinting.

 

This is the list of his kits used so far with some figures for some of the kits.

STAGE 1

Winter 2007, 2nd hand 30mm phph and scorpion fitted. Crank rebalanced and flywheel welded. Still kept same crank, gearing, clutch and barrel. Tuning work to barrel was tidy all ports and transfers and grind an extra port into barrel fed by piston.

No figues to start but was a lot faster than standard. First sprint meeting was Santa Pod May 2008 achieved 18 sec at 66mph with slipping clutch from go.

STAGE 2

Back into shop and 5 plate surflex clutch fitted with pacemaker box and brand new PM pipe as it was still a rally going scooter.

Results were good, beating a standard Rapido Race 225 and just behind Team nippa's AF tuned Rapido Race 225 at 17.8 sec and 72 mph.

STAGE 3

Pete gets informed at Isles of Wight rally Peter Bourn (Team Nippa) is to turn up at Elvington with a RB225. Pete Newbold has little money to spend and time is short(2 weeks).

Engine is stripped and all parts are found to be in a very good condition to say there Indian and the amount of use over the year.

Fitted 225 indian alloy barrel (3 extra ports machined into bore and fed through piston) and machined head to give comp ratio of 9.2-1. New mecur crank fitted just in case.

Result's against the RB225 were good. RB achieved 15.99 seconds at 83mph and our 225 cheap barrel achieved 16.5 at 77mph. We could see we had room for improvement with carb ect.

STAGE 4

October 2008 last meeting at Elvington, same weekend as Wicksteed parts fair and Team Nippa chose the later.

Fitted Rapido Race 225 and managed to get 2 extra ports into the barrel. Wanted to see what we could achieve from the kit as a road/race kit. Good news was we had just brought the dyno so we could play with the scooter on the Saturday before.

Results on the dyno were quite good, we achieved just under 20bhp with the 30mm dellorto and gained a little more by changing the exhaust for a NK. After Darrel Ward got his way with pinching my 35mm mukini it shot to 25bhp on the dyno.

Elvington was the test and it proved to be good. Pete returned from the first run with a bad time and speed complaining that the clutch was slipping in every gear. A quick strip down and replacing 2 of the thin corks for thick ones he was back out to achieve 15.98 sec at 83mph on par with the RB225 2 weeks before.

NSA OCT 19th, head wind I was to set the bottom end up as he was struggling to get it away. As I am a lot bigger 18 sec at 68mph was my best against Nippas 17.2 sec at 75 and taffspeeds 250 at 17.5 at 72 mph(first time out).once set up it was Pete's turn to give it some into the wind achieving 16.6's at 73mph.

 

Plans for next year are as follows

Rapido 250cc as per the 225 road/race kit.

6-Plate clutch

Change of gearbox, not sure at present.

Weight reduction to scooter, plus gp drop handle bars.

 

 

Daz's 100mph Scooter