Engine tuning under development

 

 

Dave's RB250 Sprinter

Change of plan from christmas.Still using the a AF RB barrel but with alot more work done to the barrel.current work load as slowed the origanal idea down.So building a something different to bring out later in year.

 

Speck is to follow and is only been shown to a few at present.-

RB250 roadscooter

AFRAYSPEED'S RB250 mark1 barrel,2mm machined of base,transfer's and exhaust port matched.

Port timing's ended up at exhaust= 186 deg,trans = 132 deg.Exhaust made for kit (road/race pipe)

Reading's from dyno are 25.5bhp at 17 torque

This is a bolt on kit with no extra tuning to case's,barrel,piston extra.

Indian 200-225cc alloy kits

Several ports added to(3 max)these kits.Alot of work required to clean them up.

225cc with 2 ports road rally tuned producing 17bhp at 15 pound of torque.

225cc with 3 ports producing around 18-21.5bhp with high torque.

Only had one piston fail so far,this due to poor rings.

Advise changing rings for AF type or simalar and replacing cylinder Head for AF or simalar.Also if using this set up with extra ports the slide will need to be richer.

Currently testing a new 210cc kit with jap piston using standard crank extra.2 ports at rear of barrel,with 9mm machined of the barrel.Very good results so far.

 

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

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

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.

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 the RB's at 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 this year are as follows

Rapido 250cc as per the 225 road/race kit.Have also spare rb 240cc to try later.

6-Plate clutch

Change of gearbox, not sure at present.

 

 

Daz's 100mph Scooter