HONDA VF750F

Jim Lind­say with part three!

Classic Motorcycle Mechanics - - CONTENTS -

With the forks sorted, the first task this month was to get rid of the old chain. The en­gine sprocket nut re­sisted the com­bined at­tempt of my wife stand­ing on the rear brake lever and me lean­ing on my long­est breaker bar. I fixed its hash with my elec­tric im­pact wrench, a rarely used but very handy tool to have around the place. Some­day I’m go­ing to treat my­self to a chain break­ing tool but for now I used an emery wheel in the Dremel to grind the riv­ets and split the chain. As usual, I draped a weld­ing blan­ket round the sur­round­ing area to kill the sparks and catch the metal fil­ings. With the back wheel out, I whipped the rear sprocket off its car­rier and sent it to join the other oc­cu­pants of the scrap bin. The chain and sprock­ets could have done an­other thou­sand or so miles, but it seems daft not to re­place them while I’ve got ev­ery­thing in bits. The cush drive rub­bers were in ex­cel­lent con­di­tion and there was no slop in the wheel bear­ings. The only thing I had to do was wash out the bear­ing in the sprocket car­rier and repack it with grease. The bike came to me with Pirelli Sport Demons fit­ted. They were the wrong width and the wrong as­pect ra­tio for the bike. They made it look weird and, what with their age and all, would have made the han­dling iffy. I popped the wheels over to my favoured lo­cal bike fix­ers to have a new pair of Bridge­stone BT45S put on. These were the orig­i­nal fit­ment back in 1985 and (as a bonus) cleaned up the looks mas­sively. Next I gave the wheels a clean. My mate Paul had left what looked like the bot­tom half of an old host­ess trol­ley in the yard we share. Its canapé bear­ing days may be over, but it made an ex­cel­lent wheel holder while I set about the gold Com­stars with clean­ing fluid and pres­sure washer. Last month, based on a quick run down the lane, I said the brake calipers seemed in good nick: a fool­ish claim!

Closer in­spec­tion showed that the rear caliper had met with an idiot armed with mole grips. The pis­tons were butchered be­yond re­pair. Us­ing the proper tool to re­move them re­vealed sim­i­larly scarred bores. Only the pads were sal­vage­able. They were Galfers, a brand I trust, so I set them aside, chucked the old caliper and pis­tons in the scrap box then, armed with hope and a head torch, headed off to the lock-up to rum­mage through the pile of bits from the spare bike. It turns out that I had a ser­vice­able re­place­ment. The front pair were in okay con­di­tion but I de­cided that it was bet­ter to over­haul the lot. First stop was the ex­cel­lently set-out David Sil­ver Spares web­site. Re­build kits for front and rear were in stock. They come with all the boots to pro­tect the slid­ing pins and bushes too, and although many pat­tern parts are great, I like to see that “Gen­uine Honda Part” stamp. A few years ago I was blow­ing com­pressed air into a caliper to eject the pis­ton without first wrap­ping a rag round the part. My garage at the time had a cor­ru­gated as­bestos roof. The pis­ton shot out of the caliper, punched a hole in the roof and hid it­self in the sur­round­ing mass of weeds. By the time I found the thing and fixed the hole in the roof, I had dou­bled the re­build time. I’ve been more care­ful since then, although in this case I need not have both­ered. Squirt­ing air down the holes made the pis­tons twitch a bit and no more. Lack­ing the ben­e­fit of a con­ve­nient idiot and his grips, I used my Laser pis­ton re­moval tool to ease the pis­tons out. I bought it sev­eral years ago for about £120. It has al­ways done the job. For firmly stuck pis­tons it has a slide ham­mer at­tach­ment. The price has gone up since then to £185 but it’s still worth ev­ery penny. It beats me why peo­ple use cop­per grease on mov­ing parts. Cop­per grease is for stop­ping stuff from seiz­ing, most com­monly nuts and bolts. It is not for lu­bri­ca­tion. It con­tains cop­per par­ti­cles. On mov­ing parts it acts like a grind­ing paste. The slid­ing pins and bushes on all the calipers were cov­ered with the stuff. Bet­ter than noth­ing, I sup­pose, but not much bet­ter. Or­di­nary grease used in con­junc­tion with the proper seals is what you need here. Any­way, still grum­bling to my­self, I re­moved the fluid and dust seals, put the dis­man­tled calipers in the clean­ing tank and left them un­der a paraf­fin jet

while I went off and made a cup of tea. Tea break over I set about clean­ing the seal grooves. I use a brass fil­a­ment brush in the Dremel for this task. It doesn’t re­move the corrosion as quickly and it wears out quicker than a wire brush, but it is kinder to the al­loy. Loads of brake cleaner cou­pled with many litres of com­pressed air fin­ished the job. It’s al­ways ad­vis­able to use rub­ber grease on the new seals be­fore you fit them and a smear on the pis­tons them­selves helps too. The pre­vi­ous span­ner­man had used O-rings in­stead of the cor­rect boots be­tween the slid­ing bushes and their hous­ing in the calipers, com­pound­ing the sin of cop­per grease. The boots are fid­dly to fit but do a proper job of keep­ing corrosion away. Gen­eral pur­pose grease on the bushes and pins is a must for smooth op­er­a­tion (not cop­per grease – have I made my point suf­fi­ciently, do you think?). The bike had some after­mar­ket brake lines when I got it. In­stead of ban­jos, these use adapters screwed into the caliper bod­ies with swivel­ing con­necters sealed by means of male and fe­male ta­pers. Fancy. I de­cided to keep them de­spite the gar­ish blue and red­dish-pur­ple an­o­dis­ing (why do they do that?). The front pads were Galfers – same as the rear – and had plenty of life in them. I gave the whole lot a work­ing over with a clean wire brush, a good soak­ing in brake cleaner and a dose of com­pressed air. I treated the backs of the pads and their re­tain­ing pins to a smear of cop­per grease. Fit­ting the front wheel on the VF750F is a bit tricky. You need to mess around with the forks to get the clear­ance be­tween the caliper mounts and the discs cor­rect. If you hear a grind­ing noise, you’ve done it wrong. Honda rec­om­mends mov­ing the fork legs in or out (with a large lever) if the clear­ances are wrong. At the first at­tempt, I got the grind­ing noises. I un­bolted the hefty fork brace, tweaked the fork legs and got it right on the third try. Back wheel in, calipers back in place at ei­ther end and out with the vac­uum pump. The rear brake bled okay but I pumped about half a litre through the front brakes be­fore I got them work­ing prop­erly. Not sure why but I was re­warded in the end by a fizzy stream of bub­bles and, at last, a de­cent feel at the lever. I re­newed the clutch fluid while I was at it. The last act for this month was to fit the new chain and sprock­ets then spin the bike up the lane to see how it all felt: so far, so good. The forks need a bit of air as does the rear shock, but the brakes work well and the en­gine feels re­spon­sive. There are still valve clear­ances to set and an oil leak from the front cylin­der head that needs to be fixed. I’ll be do­ing a few other small jobs as well. Af­ter that, it’s or­deal by MOT and, I hope, some en­joy­able miles out on the road. Yup, this project is al­most fin­ished. See you soon for the third and fi­nal in­stall­ment.

WORDS AND PHO­TOS: JIM LIND­SAY

Good heav­ens, it’s be­gin­ning to look like a mo­tor­cy­cle again.

The en­gine sprocket nut needed the bru­tal at­ten­tion of an im­pact wrench.

It’s high time that Lind­say bought a chain breaker, but at least he takes sen­si­ble pre­cau­tions be­fore grind­ing out a link.

Shar­ing a yard with a house clear­ance jockey yields use­ful finds like the host­ess trol­ley/wheel wash­ing sta­tion.

Old seals are best ex­tracted with a pick or the an­gled end of a scriber.

Dremel tool/brass fil­a­ment brush is the best way to clean hous­ings.

The proper way to do it: the Laser tool ex­tracts pis­tons without butch­ery.

This is when you cross an idiot, mole grips and jammed brake pis­tons!

New sprocket in place. Note orig­i­nal yel­low marker paint from the fac­tory!

New chain and rear sprocket by JT and Izumi re­spec­tively.

One of the re­built calipers in place. After­mar­ket fluid union is tech­ni­cally neat but the colours are hurt­ful to the eye.

Left, O-ring used by the pre­vi­ous owner. Right, the cor­rect one. Hard to fit but pro­tects the bush and pin prop­erly.

Clear­ance be­tween the disc and the caliper mount took three at­tempts!

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