Reader restora­tion: Honda MBX80

Re­stored for a pur­pose – a good one: Nor­wich-john O’groats-land’s End-nor­wich char­ity run. Made it too

Practical Sportsbikes (UK) - - Contents - WORDS JIM MOORE PHO­TOG­RA­PHY JA­SON CRITCHELL

THERE AREN’T many peo­ple who’d ride 2000 miles in four days on an 80cc two-stroke. there are even fewer who’d strip and re­store a small stro­ker in just over two months to take on such a chal­lenge. But then Rob Bill­man isn’t your usual 40-some­thing

Ps-era bike fa­natic. In the last few years Rob’s bike life has rid­den full cir­cle. Gone from his garage are the big bikes, en­duro tools and ret­ros, and in their place now sit a grow­ing gag­gle of sub-125cc stro­kers – not what you might ex­pect of a 6ft-plus, 18 stone HGV driver.

“In 2013 I sold MYVFR800 be­cause I just wasn’t rid­ing it, and I used some of the money to buy anar50 for my wife, Donna. While I was get­ting herar ready for MOT I went out on it a few times and, de­spite its tiny size, I couldn’t be­lieve how much fun it was to ride. So from then on, and also be­cause I need my li­cence for my job, I’ve had only small bikes.”

When Rob says he’s “had only small bikes” he ac­tu­ally means he’s amassed 18 and count­ing (“I think it’s 18... I lose track…”). His garage and sheds are rammed with­ars, TSS, MBS, MBXS, YSRS an­daes in vary­ing states of com­ple­tion. It’s clear he takes his small bikes very se­ri­ously. Just like his restora­tions.

His MBX made its way into his col­lec­tion back in 2014. It just “turned up” af­ter his mate said he wanted to shift it on. It was com­plete, mi­nus the bikini fair­ing, but wear­ing 20 years of patina, hav­ing last been used and taxed in 1994.

“I hadn’t in­tended to buy it and al­though, amaz­ingly, it ran, it needed se­ri­ous at­ten­tion. My first re­ac­tion was, ‘what the hell am I go­ing to do with this? ’”the an­swer pre­sented it­self when Rob and his mates, Ja­son Cooper and Roger Par­rott, con­cocted a plan to ride from Nor­folk to John O’ Groats, to Land’s End and back to Nor­folk on small bikes to raise money for can­cer re­search.

“We’d done a pre­vi­ous char­ity ride on which I’d used myar80. My knees were shot af­ter that so I needed some­thing slightly big­ger for this run. I de­cided to use the MBX. That was the back end of 2015 and we’d planned the ride for June this year, giv­ing me six months to strip and build the bike.”

That was the the­ory; prac­tice proved some­what more dif­fi­cult. Rob’s job as an HGV driver keeps him out on the road from Mon­day to Fri­day, so shed-time was lim­ited. Given that progress on the MBX was glacially slow be­tween Newyear and Easter, Rob ended up do­ing 95 per cent of the build in a lit­tle over eight week­ends.that’s just 16 days, give or take.to com­pound mat­ters, this was the first MBX Rob had ever worked on. “Had it been anar I could have done it with my eyes closed…”

Un­de­terred and think­ing lat­er­ally for any small wins that would smooth progress, Rob hit upon a ge­nius idea.an­other of his mates had an MBX, so our man bor­rowed it as a ref­er­ence tool. “Hav­ing an­other bike to re­fer to re­ally helped, es­pe­cially with stuff like ca­ble rout­ing, wiring, and fit­ting the parts you can’t see be­hind the body­work.”

Nor­wich based pow­der­coaters Master­cote UK were given the frame, swingarm and as­sorted brack­etry to re­fresh while Rob delved deep in­side the mo­tor. Know­ing that the bike had to com­plete a 2000-mile around coun­try trip in­creased the pres­sure on Rob to get the thing right first time.

“David Sil­ver Spares were re­ally help­ful. They don’t list the MBX80 on their web­site, so you have to phone up for parts. Some stuff is no longer avail­able, such as gas­kets, con­rods, pis­tons and bear­ings, so we sourced OE where pos­si­ble and qual­ity pat­tern for ev­ery­thing else.

“The bar­rel was scored so BDK En­gi­neer­ing took it out to first over­size; it’s run­ning a twin-ring pis­ton that came in a KTM box. I’ve no idea what it’s sup­posed to be in but it works per­fectly in the MBX.WHAT was ob­vi­ous when I was build­ing the mo­tor was just how well en­gi­neered these lit­tle Hon­das are.the gear­box, for ex­am­ple, runs seven dif­fer­ent bear­ings; anar has only four. It’s pos­si­bly over-en­gi­neered, but for me, with the big trip ahead, that was per­fect. I didn’t even need to touch the clutch. It was all still within tol­er­ance, so went straight back in.

“I also dis­cov­ered that MBXS run one of three types of main bear­ing. Even David Sil­ver was un­sure as to why.they’re marked with a dif­fer­ent colour. If I’d known this be­fore I stripped the mo­tor I’d have taken note of the mark­ing on the old bear­ing. But be­cause I didn’t, and also didn’t have time to swap parts if I’d got the wrong one, I got Sil­vers to send all three and then worked it out from there.”

Rob treated the re­built mo­tor, and a new-old-stock Gianelli pipe, to sev­eral coats of Si­mo­niz en­gine enamel. It’s a ro­bust and

eye-catch­ing fin­ish.the Gianelli not only perks up the power de­liv­ery, it saves sev­eral ki­los in weight. “The stan­dard pipe weighs a ton,” con­firms Rob. “It’s still on the stan­dard main jet, but I’ve raised the nee­dle a touch and it runs per­fectly.”

In the in­ter­ests of re­li­a­bil­ity and us­abil­ity Rob stuck with the orig­i­nal air­box, but not be­fore clean­ing out the dusty, dis­in­te­grated rem­nants of the old foam fil­ter.

The bog-ba­sic Showa sus­pen­sion was only ever in­tended to cush­ion bumps un­der the svelte pres­sure of a sub-10 stone teenager, so Rob’s more gen­er­ous build was never go­ing to match up with the shock and fork’s ca­pa­bil­i­ties. “The orig­i­nal shock didn’t re­bound prop­erly; there was no give in it, plus I wanted the ride to be com­fort­able if I was rid­ing it from one end of the coun­try to the other.”

Rear damp­ing du­ties are now taken care of by a shock from anaprilia RS125. “It’s a per­fect fit,” says Rob. “The only mod I had to make was shav­ing a tiny bit off the width of the top bush. It’s longer than the MBX shock so when I first fit­ted it the rear ride height was quite a bit higher than stan­dard, so I’ve backed off the preload a touch.”

The forks were an eas­ier fet­tle. Rob sourced a NOS set of stan­chions from Spain, where the MBX was a pop­u­lar ma­chine and sold as a sleeved-down MBX75. “It worked out cheaper than hav­ing the orig­i­nals rechromed. Fresh oil, seals and a pol­ish had them ready for ac­tion. Honda Com­star wheels are no­to­ri­ously fickle to re­fur­bish. Many re­stor­ers say it’s a big no-no to dis­man­tle these pressed alu­minium ras­cals – they can ping out of true and the riv­ets used to hold them to­gether are un­ob­tain­able. Rob had the ad­di­tional is­sue of a buckle in his MBX’S front wheel. He found a re­place­ment pair;“i wanted a pair be­cause they had match­ing patina.” He sub­se­quently mir­ror-pol­ished them.the fin­ish is as near to fac­tory as you’ll see.tyres are Maxxis. Al­though the MBX al­ways suf­fered a ca­pac­ity deficit against 125s of the era, this

lit­tle 80 had a stand­out fea­ture even its big­ger ri­vals couldn’t match – twin front disc brakes. It’s a fea­ture spe­cific to UK mar­ket MBXS, and much sought af­ter by Euro­pean re­stor­ers of the model. Rob’s bike came to him with the added ad­van­tage of braided hoses (overkill on a bike that weighs 102 ki­los), so a caliper clean-up and new pads were all the stop­pers needed.

Amaz­ingly, and again per­haps tes­ta­ment to the bike’s build qual­ity, the loom was in de­cent nick. a clean up and re­wrap had it back to per­fect.the only mod made by Rob was an ex­ten­sion of the switchgear wiring to work with higher and wider Ren­thal ’bars. “I had to fit them be­cause the stan­dard ones gave me ‘dead’ hands af­ter 15 miles. there’s no way I would have made the char­ity ride with­out them.”

Un­der nor­mal cir­cum­stances Rob would have taken care of the body­work paint him­self, but with such a tight build win­dow he farmed the spray­ing out lo­cally, then fin­ished it off with new graph­ics. Had time been on his side he’d have no­ticed the slight ding in the tank filler neck. “On a full tank it leaks slightly and that’s marked the de­cals on the left side. It’s an­noy­ing, but I will fix it.”

There are other ar­eas on the bike that Rob wants to redo now the char­ity ride has been com­pleted. “I’m not happy with the seat and some of the de­tail­ing. Over win­ter I’ll have it apart and fin­ish it how it should have been done in the first place.”

And what about the ride? the very rea­son for the resto.

“You now what? the bike didn’t miss a beat. I did 500 miles on it be­fore the ride to run it in and fix any­thing that might need do­ing. I had a few has­sles with the head gas­ket, but once it set­tled down it hasn’t needed re­torque­ing.

“On the ride it got filthy, and other than an oil weep from the tacho drive – the lash­ing rain must have washed a lot of gunge from

the ca­ble, and stopped once it dried up – it was su­perb. I built it to be used and that’s ex­actly what’s hap­pened!”

The ride

I’M UN­DER STRICT in­struc­tion. “Don’t worry about tak­ing it to the red­line,” grins Rob. “It takes well to a good thrash­ing.” Good job, be­cause that’s the only way to ride a small two-stroke.

Back when they were new, these lit­tle 80s used to com­pete head-to-head with 125s for the hearts and wal­lets of im­pres­sion­able 17-year-olds. al­though down on ca­pac­ity, the 80s of­fered some­thing their big­ger ri­vals couldn’t (at least not in the eyes of the law, that re­stricted all learn­ers to a pal­try 12bhp). While the 125s had their power ar­ti­fi­cially pegged down to le­gal lev­els, 80s, like the MBX, made 11 or 12bhp as their full power fig­ure. So rather than the urge drop­ping away half­way through the range in a mas­sive anti-cli­max, these tid­dlers pos­i­tively thrived on be­ing thrashed all the way around the dial.

To­day is no dif­fer­ent. Ev­ery twist of the MBX’S throt­tle sees me pin it back to the stop, be­cause the 79.7cc mo­tor only re­ally gets in­ter­ested from 7000rpm. Claimed peak power is a grand later, but Rob’s Gianel­lip­iped Honda keeps pulling right through to 10,000rpm. He’s de­lib­er­ately geared his MBX down by a tooth on the front to aid ac­cel­er­a­tion, and it works.as we exit a junc­tion I leave Rob on his full-power TS125X for dead…

From there we’re rapidly up to 50mph, then 60 af­ter that. Flat on the tank in top I reckon it’s got an in­di­cated 70mph in it. On the roads around Rob’s North Nor­folk home, snaking be­tween the dykes, fields and hedgerows of a staunchly agri­cul­tural land­scape, the Honda eas­ily holds its own with the other traf­fic.a big bike on these roads would be wasted.

De­spite my 6ft and 15 stone, the MBX doesn’t feel as small as it looks.yes it’s light and flip-flops from side to side with barely the twitch of a mus­cle, but the up­right Ren­thals, deep seat and re­laxed rearsets give it a rid­ing po­si­tion on a par with many 125s. Even the af­ter­mar­ket mir­rors, pinched from one of Rob’sars, work well.

Twin front discs are never go­ing to be stressed on a ma­chine this light.a gen­tle squeeze of the lever brings about a rapid halt. Be­ing picky I’d like more feel; dif­fer­ent pads and a fluid bleed would see to that.

For such a small bike the MBX80 leaves a big im­pres­sion – and a huge grin. It’s the best en­gi­neered of all the Ja­panese sub-125s, bet­ter equipped than many mid­dleweights, and ca­pa­ble enough to eat up 2000 miles in all weath­ers and fours.that’s not only a credit to Honda’s de­sign, but Rob’s resto too.

Braided hoses were al­ready fit­ted “Wanna race?” The MBX leaves the TS125X for dead Ren­thal ’bars make dis­tance work eas­ier A ding in the tank neck is on Rob’s list to fix

Jim has to pinch him­self but misses quite badly Nice pipe rack – you can al­most feel the noise This lit­tle line-up or a VFR800? No con­test Wheel meet again, don’t know where...

Tid­dler trea­sure trove: MB8 un­der card­board box

Looks clean, revs crisply, what a lovely bit of kit

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