Reader restoration: Honda MBX80
Restored for a purpose – a good one: Norwich-john O’groats-land’s End-norwich charity run. Made it too
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!”
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