One of only 5 sand-cast test prototypes
Here’s a news item gathered at the recent Rabbit 24-hour race in Italy.
BFA-FRT 165 and 180cc kit for Piaggio/SIP smallframe engine cases
It seems that the market for large-capacity low-rpm smallframe kits for road use is bigger than anyone anticipated.
It’s all very well having a 30+hp smallframe motor, but if it runs at over 10,000rpm and sounds like a MotoGP 125, then it will always attract the attention of the boys in blue.
Eugenio from FRT is working together with partners BFA on an aluminium large-capacity kit for road use, which fits onto Piaggio or SIP engine casings. Not needing new casings should make this large-capacity conversion more affordable than swapping to high-end casings.
You can see where the cylinder stud passes through the massive transfer feeds
Option 1 is the 165cc; achieved using a standard 51mm stroke crankshaft with a 105mm con-rod. The cylinder has a bore bigger than the hole in the casings for the cylinder spigot, so you must open out the first 6mm of the crankcase mouth to 69mm to accommodate the cylinder. Alternatively, you could use an even longer con-rod and open a packing plate to the 69mm cylinder spigot, then the kit would fit without need for any serious casing modifications.
Option 2 will be a 56mm stroke 185 version; which requires the crankcase to be bored to accommodate larger diameter crankshaft webs. The 56mm stroke crank needs to have a 110mm rod. BFA will be producing a specific crankshaft to suit Piaggio and SIP cases; which will be ready for the launch of the kit.
8-point head fixing
The piston for both versions is a 64mm Wossner, designed specifically for this kit; using a 15mm gudgeon pin. Conversion bearings are available if your con-rod normally works with a 16mm pin.
This prototype has three exhaust ports but the design is not yet definitive
Sub-port exits feed into an oval outlet
The barrel is an interesting design because the cylinder studs pass through the transfer ports. At the moment Eugenio from FRT is experimenting with various exhaust port configurations in order to figure out what works best. The example I saw used a triple exhaust port layout, but the position of the cylinder studs necessarily compromised the sub-ports. It could be that a different layout works better. Only testing will find out.
The target is 25-30hp for a 165cc kit and 30-35hp for 185 at moderate revs, using a selection of off-the-shelf exhaust systems; allowing the kit to pull relatively tall gearing.
The kit uses a TM reedblock feeding through a bridged inlet and into Boyesen ports straight to the transfers
The inlet design uses a TM reedblock with a choice of manifolds. There will be S-shaped options for 40mm or 35mm, located in the frame in the usual position. Alternatively, there will be short rubber manifolds, rotatable to different positions if you have a cut frame, or even allowing the cylinder to be mounted reversed, with the carb at the back.
The kit is expected to enter production later this year. Price is not yet set.
FRT Clutch Components
Two interesting clutch parts are shown in the video. The universal clutch cover should fit with every type of performance clutch on the market. It uses rack and pinion (like XL2) to reduce hand strain.
The floating clutch cable bracket should also work to reduce hand strain by ensuring that the clutch outer cable is always at the optimum position with respect to the inner cable no matter which clutch cover you use. The RRP for that is 40 Euros.
FRT also make this tidy smallframe gear linkage set. The cable pulley has two sets of holes, to locate with either smallframe or PK positions and the shaft has space for 2 O-rings to prevent oil leakage.
Words and Images: Sticky
Where to get FRT in the UK
- Green Light Scooters: FRT are supplied in the UK by Adie Horrocks at Green Light Scooters, you can contact him via Facebook here or call him on 07789 763400.
Hornet Racing
- Hornet Racing: FRT are also supplied, fitted and raced by Dave Bristow at Hornet Racing, you can contact him here or call 07950 321404.
