Jerry Thurston recom­mis­sions a Honda Cub!

Classic Motorcycle Mechanics - - CONTENTS - WORDS AND PHOTOS: JERRY THURSTON

So, this fea­ture is all about the most com­mon mo­tor­cy­cle of all time, one of the 87 mil­lion Honda cubs built be­tween 1958 and to­day (well, 2014 ac­cord­ing to Wikipedia!). This Honda Cub is a 1969 50cc vari­ant that had gen­uinely been in a barn for years and al­though it is pri­mar­ily to be used as pad­dock trans­port at his­toric race meet­ings as it will be on the road at some point the work has been done to MOT stan­dard. If you’ve been lucky enough to find a mo­tor­cy­cle that’s been in the prover­bial (or real) barn for decades it al­ways looks like it could be up and run­ning with­out too much dif­fi­culty. But rather than just slosh­ing some fuel in and giv­ing it a kick let’s look at what’s in­volved in a care­ful recom­mis­sion­ing of some­thing that’s been stand­ing for ages. Here’s how I did it and what it cost! The first job is al­ways sim­ple: give the whole ma­chine a good clean and de­grease. It is go­ing to be far eas­ier to see what you are do­ing and when you re­move com­po­nents you won’t have muck get­ting into the mo­tor. I al­ways drain the old oil overnight and if the ma­chine has any sort of oil pan, pull this off – there is of­ten a con­sid­er­able layer of muck sit­ting in the bot­tom ready to be sucked up by the oil pump! Then fresh oil and re­place any fil­ters be­fore you kick it over. The Honda has no fil­ter, re­ly­ing in­stead on a cen­trifu­gal fil­tra­tion sys­tem fed via a gauze strainer. What Honda rec­om­mend is drain­ing the old oil, re­mov­ing the right-hand side cover and clean­ing the gauze (the gas­ket is £9.50). Given that it holds a scant 0.7 of a litre (2L semi syn­thetic 10/40 £10) I went fur­ther and once it was run­ning changed the oil twice in quick suc­ces­sion, but I’m slightly ahead here, we need to get a spark first! I needed to con­nect a good bat­tery: this one is 6V but later Cubs are 12V. I man­aged to get a good qual­ity 6V 4 amp bat­tery for £18, not for­get­ting to put the neg­a­tive to the blue wire, pos­i­tive via an 8 amp fuse to the red. Be­ware though, If you find a ‘faded’ red wire and con­nec­tor, ig­nore it, it’s not faded it’s meant to be pink and it’s a spare. The pos­i­tive needs to go to the bright red dou­ble con­nec­tor that comes from the flasher unit. I al­ways do a quick test for power when the ig­ni­tion switch is switched on by press the rear brake lever or try­ing the horn, if you get light or a peep, it’s all good to go. To check for a spark, I push a spark-plug into the cap and rest it on the cylin­der head, ig­ni­tion on and kick. OID school: but I find I have no spark, so it’s time to change the plug and check again. Still noth­ing so I need to go deeper. The Ig­ni­tion/ gen­er­a­tor sys­tem on these ear­lier ma­chines is pretty ro­bust, so I fig­ure that a sim­ple clean of the points through the fly­wheel might work. I’m still get­ting noth­ing so it’s fly­wheel off to in­ves­ti­gate fur­ther; the cor­rect left-hand thread 27mm puller is about £8 so it’s not worth risk­ing dam­age us­ing any­thing else.

With the points out a sim­ple con­ti­nu­ity test proved that they didn’t pass cur­rent but a re­ally care­ful clean with the blade of a knife sorted this out (gen­uine re­place­ments cost £16). If the points are good and there is still no spark, you can check the con­denser, set a multi-me­ter to ohms, place the pos­i­tive ter­mi­nal on the cen­tre con­nec­tors the other to the body and hold for a few sec­onds, this should charge the con­denser slightly, change to the volts set­ting and do the same again and if it’s good you’ll see the read­ing fall as it dis­charges, (by the way, a gen­uine con­denser is £16). At this point I had spark but if you are strug­gling, check all the wires, look­ing for dirty con­nec­tors or a break some­where pay­ing par­tic­u­lar at­ten­tion to any pinch points. Even if you have a spark it’s worth do­ing this, I found two trapped and dam­aged wires in the rest of the loom which needed at­ten­tion. With a spark I was now on my way, but it’s not time to try a start yet. I de­cided to check the fuel sys­tem first. Top tip, the fuel tap is on the carb not the tank on these early Cubs so have a con­tainer ready for when you pull the lines off! Once the tank is empty look into the fuel tank with a torch; hope­fully it’ll be clean and bright, but any flakes of rust are go­ing to clog things up. A hand­ful of small nuts and bolts care­fully rat­tled around will scurf most of the rust de­bris, fol­lowed by a de­grease then tank rust re­mover. Be­ware though, as this will search out any pin holes es­pe­cially in the seams. If you de­cide that you are merely go­ing to live with it, a £2 dis­pos­able fuel fil­ter in the line/s (the Cub has two, one main the other re­serve) will save much angst later. A thor­ough clean of the re­main­ing fuel sys­tem is al­ways pru­dent and I re­placed any hard­ened or rot­ted lines and I also gave the carb and the jets a once over with car­bu­ret­tor clean­ing fluid and com­pressed air. Time to give the ca­bles and con­trols some at­ten­tion too! The Honda’s throt­tle was sticky, which I fig­ured was dan­ger­ous even on a 50! The twist-grip was stripped and re-greased and the ca­bles were checked for dam­age and when passed fit it was re-lubri­cated. The dif­fer­ence this made to the con­trols was a rev­e­la­tion and it’s al­ways worth do­ing on a recom­mis­sion. I don’t trust brakes un­til I have checked the shoes, but be cau­tious, old brakes may

still con­tain as­bestos lin­ings, never blow them out with com­pressed air. I tackle un­known brakes while wear­ing an air-fed mask and even then I squirt lots of pen­e­trat­ing oil into them while they are still on the bike to damp them down, then re­move and wash ev­ery­thing in old two-stroke oil which doesn’t dry out. Only when they are sur­gi­cally clean do I use brake cleaner to re­move the oil residue. I sup­pose I should say that this is what I do, not a rec­om­men­da­tion of any safe tech­nique! Mine on the Cub had a com­plete strip-down, cop­per grease on the piv­ots and new shoes (gen­uine, £10 for all!). While I was there, I re­alised that the cush drive rub­bers of­ten suf­fer over time and mileage, so I checked and mine were shot but were easy to re­place while the wheels are out to check the brakes and a gen­uine set came in from ebay at just £18.85. I had the wheels out so I checked the spokes. As a min­i­mum, I check for any bro­ken or loose spokes and give the wheel a spin to check that it is rea­son­ably true. Both of mine were, which was a re­lief as I would have had to bud­get for a wheel­re­build oth­er­wise! Decades-old tyres and tubes will un­doubt­edly be past their best, so I re­placed them. I bought Miche­lin Street Pi­lot, one size up at 2.50 x 17 for £37 pair and the tubes were £15 pair. The ex­haust is where I went to town. On any old four-stroke this is likely to be rot­ten, a pat­tern re­place­ment is £36 but be­cause this ma­chine is go­ing to be used as pad­dock trans­port I took the op­por­tu­nity to fit the only non­stan­dard part on the ma­chine: a stain­less steel Kep­speed race pipe which was a ‘whop­ping’ £89.95! With the ’69 Cub MOT ready I had a to­tal recom­mis­sion­ing bill of £297.02, al­though this did in­clude a few ex­tras that weren’t strictly nec­es­sary, such as a new seat cover (£35) and footrest rub­bers (£10 pair), the chain was mar­ginal so was re­placed too, with­out these and the ex­haust up­grade my costs would have been £109 less, but I’m happy! cmm

She cer­tainly needed a good recom­mis­sion!

Jerry went through the bike me­thod­i­cally.

ABOVE: She’s go­ing to be used, so it’s not a nut and bolt resto.

BELOW: Work was needed on the mini-mo­tor.

Cleaner, safer and bet­ter than be­fore: if not im­mac­u­late.

Nor­mally an area for rot!

Forks and spokes need to be A-OK.

Yeah, best re­place that.

Newspapers in English

Newspapers from UK

© PressReader. All rights reserved.