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Little Brother

by Mark Daniels

Motobécane’s AV88 was a model primarily created for sales into ‘restricted performance’ markets, particularly France and America and, despite being listed over a 10-year period in the UK, proved a less popular model since it was largely eclipsed by its more powerful and faster ‘Big Brother' AV89.  While the AV89 is fitted with a big-port cylinder, 9:1 compression ratio head, H14mm carburettor, and is rated at 2.7bhp, our ‘Little Brother’ appears positively weedy by comparison with a split-fin standard-port cylinder, a miserable 6.5:1 compression ratio head (which was carried over from the old AV78), a frugal AR10mm carburettor, and rated at … about 1.5bhp we guess?

The cylinder head disc shows serial number 2803184 and, since the bike was UK-registered in October 1961, we would probably have been expecting a continuous-fin 1.4bhp cylinder to be fitted, but this split-fin 1.7bhp cylinder carries the same engine number, so these certainly look like the original components.  (Raleigh first notified dealers about the ‘new’ 1.7bhp split-fin engine in Raleigh Service Memoranda No.7 dated 1st April 1963.)  This low power engine is then fitted into the same frame as the AV89, with the same swing-arm rear suspension, but telescopic forks instead of Big Brother’s leading-link front fork at the time … yes, this could represent a fair bit of metalwork for such a low power motor to be dragging around, so there’s immediately some apprehension that the AV88 is likely to be a pretty poor performer.

Mobylette AV88 With our feature machine dated at 1961, the first thing to do is look at further differences beyond just the motor specification.  There have to be a number of these to account for the selling price comparison at the time: AV88 = £76–19s–6d, AV89 = £85–19s–6d.  The seat is pretty obvious, AV89 had a dual-seat, where AV88 has just a single saddle, but look closer for another associated subtle difference … AV88 has no rear footrests, which would normally be mounted off the rear suspension unit shrouds, so AV88 wears a different set of ‘economy’ rear shocks with no footrest fittings.  Instead of the pillion seat the rear frame is topped with a pressed steel carrier, which in the case of our example carries a wicker basket.  Notice the early style of ‘arched’ rear mudguard; the AV89 had already replaced that with a ‘squared-valance’ guard even while it still had the band-suspended leading-link fork set.

AV88 certainly wears a big rear sprocket!  Count the teeth on that shark!  54!  AV89 has a standard 48T rear sprocket to give a high drive ratio to match its higher power output for a greater speed.  AV88 is running a 12.5% lower drive ratio, which is quite a lot of gearing down!  The larger rear sprocket also means that it would be too big to fit into AV89’s fully enclosed chain case so, basically, there isn’t one, just a half-length chain case backplane to function as a splash guard, preventing water being thrown directly onto the chain runs by the wheel.  This gives a lightness and cost economy necessitated by the larger rear sprocket.

88 has the same alloy, full width 8-rib × 100mm Prior hubs as 89, but the front brake plate is the leading-link type ‘cross pattern’ alloy brake plate, and we’ve never before seen this fitted to a telescopic fork set.  This means the brake lever faces forward instead of back, and the cable routing is completely different.  The rear brake plate is also changed, just a conventional, old style, 100mm plain alloy disc type instead of AV89’s special cast brake plate to suit the fully enclosed chain guard set.  The difference makes sense, but it’s almost as if the AV88 was built using up cheap old leftover parts?

OK, we think that’s pretty much it with the differences, so what we basically have with the AV88 is a low powered motor in a relatively heavy frame, but geared down to compensate for the loss of power.  Weights for the dual-seat AV89 were given around 90lb and the AV88 about 86lb, but one may doubt those figures since Raleigh quoted the RM5 (AV89 equivalent) at 112lb, and even the lightweight RM11 Super Tourist weighed in at 102lb.  Though some of the cycle fittings are cheaper on 88, and maybe it is actually a few pounds lighter than the 89, any small weight difference of a few pounds is unlikely to have any performance effect worthy of consideration.

Mobylette AV88 Starting is the familiar old Moby procedure, fuel tap pushed down for on.  We opt for a flying start on this occasion since the centre stand has ‘settled’ too much to ‘kick-start’ on the stand; so twistgrip forward to decompress, thumb the trigger choke under the left-hand bar, pedal away.  The motor spins, twist back the throttle … and 88 fires right away, a couple of coughs as it seems indecisive whether it wants choke or not, then clears its lungs and we’re away.  The initial acceleration quite takes us by surprise!  We weren’t expecting it to pull that well from a start!  It’s immediately obvious what a difference that larger rear sprocket makes, though we’re also expecting 88 to run right out of breath as the speed picks up, but it doesn’t seem to do that within the urban area, snapping readily up to an indicated 25, then on to 30 … hold on, this doesn’t feel like 30?  A wave summons our pace rider to attendance for a comparative check, and sure enough, our 60mph Huret is already reading over 5mph fast, so that speedometer is probably going to be about as accurate as a wind sock!  Our outbound readings, struggling against a light headwind with a cold motor, were all bettered by the return-leg readings with a light tailwind and hot motor.  Best on flat (paced readings since our Huret speedometer indications were far too fictional) 30mph outbound, 32mph inbound.  Downhill run (long shallow slope), pace 38 (indicated 48/49), following uphill climb (short/steep ascent) dropped to 15mph over the crest.  Second downhill run (short/steep descent), wow: indicated 50mph!  (Only to be crushed by our pacer confirming this was actually only 40), following uphill climb (long shallow slope) dropped to 18mph over the crest.

Mobylette AV88 Overall the AV88 performed surprisingly better than we might ever have imagined.  As a result of the variator transmission and low overall drive ratio, acceleration is fairly capable up 25mph, so 88 makes a reasonably effective ’ped for urban use.  The general ride, handling and brakes proved more effective than many other period economy commuter mopeds we ride, and from a starting point of expecting to be slating the 88 by the end of our run–we’re surprised to report, it did go quite well!  The low power motor expectedly fades pace on hills, but it confidently got up every ascent without calling for any pedal assistance, so we’ve got to fairly report that it capably did the job.

The Huret speedometer was a joke; a 25% indication error at just 40mph was not the kind of ‘misread’ you could account for in anything pertaining to call itself an ‘instrument’.  You’d get more accurate readings off a kiddie’s plastic watch from a Jamboree bag!

The lights were … well … dull and inadequate by today’s standards, but typical of the time and adequate to be seen by, so would probably be considered fair for their day back in 1961.

Mobylette AV88 The AV88 Mobymatic (Mk2) was priced £76–19s–6d from its initial UK listing in November 1960.  (The Mk2 aspect related back to the older ‘plunger’ AV78 model, which originally introduced the ‘Mobymatic’ name, hence the 88 technically became its ‘Mk2’ replacement.  Comparatively the AV89 Luxamatic at this time was priced at £85–19s–6d.

The AV88 listed through 1961, though was not represented in the UK line-up for 1962, seemingly replaced by a single-seat AV89 Luxamatic at £85–19s–6d, while the dual-seat AV89 rose to £89–19s–6d.  AV88 appeared to return again for 1963, now as the Mobymatic De Luxe priced at £84–19s–6d with the single-seat AV89 still at just £1 more.

1964 now found an AV88D Duomatic model (for dual-seat) priced £87–19s–6d, while the single-seat AV89 was now £94–19s–6d.  The AV88 was listed right up to the ‘B-Duomatic’ model in 1970, and then quietly fell off the radar.  It was only ever an ‘also-ran’ model in the UK, and is rarely encountered, which goes as some indication that not so many were sold into the British market.

Of recent times however, more AV88s appear to be turning up as people seem to be bringing back cheap ‘grey imports’ from France, as the French no longer seem to have so much interest in old mopeds that now require registration and are subject to standardised regulative European demands.

Next—We feature quite a rare machine with a foreign sounding name, which was sold under a British branded badge from a sporting car background, that was also used to promote its sales … (though the bike actually happened to be a German import anyway).

An interesting story of ‘Racing Heritage’ lies behind this bike, and we’re pretty sure the detailed research behind this next presentation will instantly establish itself as the reference article for this obscure moped.

This article appeared in the July 2015 Iceni CAM Magazine.
[Text & photographs © 2015 M Daniels.]

Making Little Brother

Our Mobylette AV88 was another moped that came from the Derek Scott collection, which was purchased in its entirety by the workshops as a commercial project, who returned the bikes to operational and registered status for selling on, but presenting an opportunity to IceniCAM with the pick of any vehicles wanted for road test as they became completed.  The AV88 was road tested & photo shot in July 2014, then subsequently sold on.

AV88s are basically AV89s fitted with a low power motor, but you can usually spot a proper AV88 by the 54-tooth rear sprocket, which lowers the drive ratio.  Any AV89s with the ‘wrong engine’ are never done properly, and invariably still run a 48-tooth rear sprocket with the wrong chain-case.  Sometimes you see hybrids with the low power 1.7bhp cylinder but fitted with the H14 Gurtner carb and 9:1 head, which can make them go a little better, but they’re still short of the AV89 mark.

Our AV88 was a particularly interesting and very early example, still with its original engine, and while still falling short of the full-blown AV89 2.7bhp specification, performed rather better than we might have expected.

Being registered in October 1961 meant our machine was less than a year old from introduction of the model in November 1960, and Motor Imports probably wouldn’t have begun selling many until the commencement of the next season around March or April 1961.  Our example was almost certainly produced to the original UK market specification and hadn’t been messed about, so made an ideal feature machine for the article.

Sponsored by EACC member Russell Newsome, Cleveland, with a modest donation to IceniCAM in appreciation for lots of assistance in restoration and registration of his Mobylette AV42, saying any Mobylette feature would do.


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