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

Magazine, International motorcycle catalogue 1988-1989

 The 'International Motorcycle Catalogue' was a model listing directory published annually. I had several from period and I am missing the 1990 one with the Futura generation in, if I find it I'll update. Here are all the listings for the AF1 series.

My bike, wheels 2

I picked up my wheels from the powder coaters today, I got to say they have done a great job as usual and most importantly got rid of all the corrosion and given it a finish that should last another 30 years!

I will have to do a little prep on them as there is an area on the rear wheel that should not be painted, so i'll be super careful and remove this myself.

The conundrum now is do I fit the old tyres, which look good but ate 5 and 7 years old, or fit new tyres? What would you do???

My bike, wheels, mudguard, loom, footpegs

This week I needed to progress with the final big jobs, firstly the wheels were looking worse the more i looked at them, I found a local dealer (to me) in Waterlooville called Bike Shed who could remove my tyres while I waited. They are a little local motorcycle workshop run by a couple who had been there for 19 years, super nice people, very chatty, very old school in a good way, I be using them again!

Ive now removed the front disc and the front wheel bearings and dropped them round to Plasticoat Powder coaters who I have used before

I fitted the rear inner mud guard, routed the zip tied the loom, fitted the rear foot pegs and generally replaced and bolts and nuts with stainless items.

Saddle

I had previously ordered a pair of seat covers from a company in Italy called Volcano Industry I got say these are amazing, fit, finish, colour all spot on. The covers are tailored to the original shape with an elastic strap sewn on the inside with you can pull about and staple down. I actually run out of staples so the job his half finished until more turn up this week. I will post again the finished articles.

Brochure: AF1 Sintesi 1989

 AF1 Sintesi 1989 brochure - unfortunately its not original copy but I am working on getting a high-res update. :-)

my bike, swing arm rebuild

After getting the swing arm powder coated I wanted to get it back on to the bike could get back on its wheels and I could have a shuffle about.

First thing was to get the main bearings (4) back in to the pivot, these are super snug so lots of grease is needed. TIP, place the bearings (4) in a freezer for 10 minutes then install them in to the swing arm. The cold will make the bearing contract a little and make installing them a little easier. Fit the O-rings (7) to each side of the roller bearing and grease liberally. At this point I put the pins also (5) in the freezer to shrink a little while the roller bearings expanded to their normal size. Next I just slid the pins (5) in the bearings (4), easy!
Next I installed the bearing shields (3) to each end, again with grease so they wouldn't easily drop off.

The next stage was to offer up the swing arm to the main frame and slide the main pivot axle (2) in to hold it there.

The next stage was to get the rear shock and the shock linkage fitted. The shock can go in via the top or bottom but you will have to raise and lower the swig arm at points to get every bolt it. Again grease all bearings, and plenty of it.

I re-fitted the rear hub then re-fitted the wheel to be able to move the bike around but it will need to come off again for power coating.

Note, the wheel has a boss (1) on it which mates to a cut out on the rear wheel, make sure you do this.

Lastly I fitted the chain slider.

Torque values. 

The workshop manual states torque values in daN.m- Dekanewton, where the more common values now are in Nm - Newton, the conversion is just one decimal point or x 10 for ease, I have included both.

Shock linkage bolts including the top shock mount (fig 88 + 89) = 5 daN.m or 50Nm

Main pivot = see fig.92 follow correct procedure:

• Complete unscrew the adjustment boss on the right hand side (3)
  
• Insert the pivot axle and screw it in a few turns
• Screw the adjustment boss (3) and torque to 1 daN.m or 10Nm
• Tighten the retaining lock nut (1) in using the notched Aprilia tool to 2.5 daN.m or 25Nm
• Tighten the main pivot axle to 8 daN.m or 80Nm

Wheel nuts = 8 daN.m = 80Nm

Main axle shaft nut (fig91, part 4) = 8 daN.m or 80Nm

this nut is torque to 80Nm, which may require an extension bar... 

main pivot requires a procedure to correctly tighten.

My bike, parts pull down and paint prep

In order to move this project on I have taken the nuclear option and applied to take the AF1 to Stafford in October as there is nothing like a deadline to create motivation!

First thing was to get the rear subframe and swingarm off and get them to the powder coaters. I hit a small hurdle in the fact I don't have the swing arm main pivot lock ring tool, but a screwdriver and hammer moved that. I removed the rear hub, rear shock then main swing arm pivot and then finally the swing arm.

With the swingarm off the chain sliders were removed and the lower one has broken, so replacements will need to be sourced, and the bearings removed for painting. 

Taking the back end off and seeing the wheels also confirmed I need to look at getting these painted also.

Other progress: I ordered the decal kit of e-bay and started to clean a lot of the loose parts.

a few chips on the rim, meaning these need paining 

rear subframe ready for painting

swingarm ready for painting

cleaning up the rear of the engine case and frame mount

rear shock and alloy rocker cleaned

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