My bike: front wheel bearings

Last year when I had my wheels powder coated I re-installed the used wheel bearings just to get by, but always knew that these would need replacing if I wanted to MOT the bike. Now I am pushing to get the bike on the road in time for the two stroke meet at the Sammy Miller motorcycle museum on the 19th July.

Jobs to complete are:

Wheel bearings
Clean carb - fit new needle
Clean petrol tank and replace fuel
New spark plug
Possibly a new battery
MOT

Wheel Bearings

Looking online wheel bearings of the same quality can vary from around £15 pair to £20 each, and to make it worse 'AF1' bearings seem to cost more than RS.

Checking several sites it seems the bearing is the same on both the AF1 and RS (at least MK1), the key information is that you need you need bearing 6004, size OD 42, ID 20, width 12mm. Aprilia part number AP8110044

I ordered a pair of KOYO bearings from TWSR Motorsport on ebay for £13.75 a pair delivered.

OD 42mm, ID 20mm, width 12mm

cleaned, greased and ready for the bearing

The most difficult part of this job is that the bike only has a side stand, so for security I tied a strap over a rafter in the garage and the top yoke, this way the bike wouldn't drop. When I removed the front wheel I placed an axle stand under the fork leg as an added precaution. Once you have drifter the bearings out, cleaned and re-greased I used an old bearing to help seat the new, bearing careful to keep the bearing square and even and not to damage the dust seal on the bearing. Just an observation, the original bearing only had the outside seal and the inside of the bearing was open, the replacement were double sealed.

breath easy, wheel and axle back in

Deep dive, Sintesi 88 - type EH

More than any other generation, the 1988 Sintesi AF1 125 was a huge jump forward and offered the 125cc class features rarely seen on superbikes let alone on learner legal motorcycles. At the time it was compared to the mighty Honda RC30 superbike racer for the road, which is high praise indeed, but again this was a 125cc motorcycle you could ride at 17 (UK) making it even more remarkable.

The updates over the previous Project 108 model were considerable with the new bike featuring all-new bodywork including twin round front headlights, GP inspired radiator openings on the fairing, separate seats for the rider and pillion, with the pillion seat colour coded to give the elusion of a single seat unit. The metal fuel tank hinged upwards to gain access to the spark plug, battery and coolant reservoir. The stock Sintesi gained bold new graphics with a purple colour band which were very much in-tune with the younger generation of the era. For the UK (and export) market we gained the classic Reggiani Replica with striking graphics and the number 6 proudly displayed on the tail piece. This bike featured heavily in the UK media and helped put Aprilia firmly on the map.

Chassis updates include:
All new twin-spar aluminum frame - significantly lighter and stiffer over the steal frame it replaced.
Alloy 'rear set' foot rests for the rider and pillion.
38mm upside-down fork - 4 years ahead of the Japanese
Single-sided swingarm and APS suspension - carry over part from the project 108
New 17" multi spoke wheels - sizes: 100/80-17 front and 130/70-17 rear
New 320mm floating front disc brake with a four-piston calliper

Engine updates include:
The new Rotax 123 replaces its predecessor, the 127, and remains a mainstay of the Aprilia range up until 1994, when it was replaced by the Rotax 122. Here are the most important new features:

New aluminum cylinder with Gilnisil-treated liner
New two-piece cylinder head for improved cooling.
Stroke 54 x 54.5
Compression ratio dropped to 15:1 (15.5:1 on the Replica).
Balancer shaft (not present on the Rotax 127).
Dell’Orto PHBH 28 RD oval-section carburettor.
Rave 2 pneumatic power valve
New airbox with dynamic air intake mounted on the right side of the bike.
Maximum power output of 28.66hp at 10,500 rpm

A, B and C versions
In early production the fuel cap is located on the right hand side of the fuel tank and without the breather hose, with the vent integrated in to the fuel cap. These early models can be identified by the codes "A" and "B" which are visible on a decal on the seat subframe.

All subsequent production bikes have identification code "C," on this version the fuel cap moved to the left side with an additional external vent on the right.

Left side, AB fuel tank, right side C fuel tank

Colours

Black, purple, white and red

Dark blue, aquamarine, white and red

Replica

There is a forth colour that appeared in a bike listings catalogue which I am not 100% clear if this was a pre-production colour that got dropped for another option, a low production colour (I have not seen another one?)or even a colour mishap in the print process!

Black, green, white and red

Road Test; 1988 Sintesi Replica 125

 Motorcycle News road test from October 4th 1989 featuring the AF1 Sintesi Replica (type EH)