Jeff Ware strips the square four mo­tor. What does he find?

Classic Motorcycle Mechanics - - CONTENTS -

G’day! There have been a few is­sues since my last up­date. Hope­fully you en­joyed my story about the Aprilia RS250 restora­tion and sadly, in­evitable sale, such is life… The RG500 is be­com­ing a bit more of a task than I had hoped for but I’m try­ing not to get too fussy. I want it ready to ride for spring over here so I only have a few months. It’s too cold now, be­ing win­ter and only 15C most days (well it’s cold for us Aussies). I’ve also just re­stored a 1985 GSX-R750F from scratch, which just needs to be dressed now, so that has kept me busy. The RG500 car­bu­ret­tors were really grubby. Of all things not drained or pre­pared for 17 years’ stor­age, it had to be the car­bu­ret­tors. The fuel tank was empty but the carbs not drained. I’m not sure why. Any­way, the re­sult was se­vere clog­ging up and crys­talli­sa­tion as fuel evap­o­rated or turned to syrup over the many years the RG stood still on its stands. One car­bu­ret­tor had a bro­ken float pin post – it had clean snapped off, so re­pair­ing that was tricky. I drilled out the pin and the carb body and tapped a stain­less pin into it and joined them to­gether again with some liq­uid steel. It worked a treat. I also fit­ted a new float to that carb as the orig­i­nal one was dam­aged. With the carbs fully stripped I popped them in the ul­tra­sonic cleaner and got them all mint again, back to as new. You can’t beat ul­tra­sonic clean­ers in my opin­ion. The one I used be­longs to a mate, so I just headed over to his shed, beers in hand, popped them in, had a beer, re­turned the fol­low­ing arvo for a few more am­ber re­fresh­ments and gave the trick lit­tle flat slides a rinse and blow out, then stum­bled my way home. We have no foot­paths here, so I was pretty an­noyed when I tripped and dropped my im­mac­u­late, clean car­bu­ret­tors in the dirt. Bug­ger! I as­sem­bled the fan­tas­tic four with brand new jets and sat them aside ready to pop back on once the new ro­tary discs and O-rings ar­rive, which should be by the time you read this. Once they are fit­ted I can re­fit the carbs and bal­ance the slides.

The next job to tackle was to in­spect the clutch and gear­box, just make sure ev­ery­thing in­side the bike was in good or­der and that no nasty sur­prises were go­ing to be had once I hit the open road on my dream bike. I’m happy to re­port that all was fine in­side the bike and noth­ing at all needed re­plac­ing, not even a clutch plate or spring. I’m amazed at the con­di­tion of the gear­box and clutch con­sid­er­ing the mileage of the bike. It says a lot for reg­u­lar oil changes and treat­ing a bike with a lot of TLC through­out its life. I no­ticed in Hel­mut’s main­te­nance notes that he reg­u­larly added Nu­lon gear­box ad­di­tive to the gear­box each oil change. A bit like the Slick 50 myth, per­haps th­ese things ac­tu­ally do work! I reckon very few of us ever own any­thing long enough to in­spect and as­sess wear to find the truth… Well, this may be the answer! I was hop­ing to get the pipes off, de­coked and painted but have not had a chance and I need to paint the wheels, re­place the fork seals and re­build the brakes first as the bike is be­ing sup­ported by the pipes right now. Once I do get the pipes off, I can do my fi­nal en­gine in­spec­tions, in­clud­ing power valves, and then assem­ble it all and fire the bike up. I can’t wait… Chas­sis-wise I’ve got stain­less steel

brake lines by Ven­hill to fit to the bike, as I really do want good brakes. I haven’t de­cided on rub­ber yet but will most likely go for Pirellis and I want to re­place the shock but need to do more re­search, so any of you with any sug­ges­tions on RG500 shock re­place­ment, let us know – any advice ap­pre­ci­ated. I also bought a sin­gle seat cover as I really want that look as I think it really sets the bike off. Next is­sue the bike will be run­ning, with freshly painted pipes and ra­di­a­tor and a new lease of life. Hope­fully I will also have the wheels painted and wear­ing new hoops and might even have the brakes done.


11/ The car­bu­ret­tors be­ing stripped to go into the ul­tra­sonic cleaner. They are a really neat lit­tle car­bu­ret­tor and easy to strip.


52/ The re­paired float pivot post that was bro­ken off. I drilled it out and fit­ted a stain­less steel pin in­side, which worked fine and saved me a small for­tune. 3/ This is the jet kit I bought from Ja­pan. I have heard and read both good and bad re­ports about th­ese so will have to see for my­self once I get the bike on the dyno for tun­ing. The kit comes with ev­ery­thing needed and at the right price so I am more than happy to give it a go. I also have the orig­i­nal jets, although they are most likely worn. 4/ Got this float out of Sin­ga­pore of all places. It wasn’t easy to find a sin­gle OEM RG500 float! 5/ The car­bies were fully stripped and placed in an ul­tra­sonic cleaner for 24 hours. 6/ All like new, they came out really clean ready for new jets, new nee­dle and seats, gas­kets and O-rings.




10 10/Float heights set and mix­tures. Slides will be bal­anced later. 11/ The ex­haust pipes need a clean-out and re­paint so that will hap­pen as soon as I can get the bike sup­ported at each end, which will be af­ter I do the forks and source a shock, plus check the swingarm piv­ots. 12/ Bit of RG500 in­spi­ra­tion never goes astray in the shed!


8 7/ The car­bu­ret­tors came up mint, all ready to be re­fit­ted and bal­anced once the man­i­folds are back on, which de­pends on the ar­rival of the ro­tary discs and O-rings for the cov­ers. 8/ This is what each carb looked like af­ter stand­ing with fuel in them for 17 years!. 9/ The clutch and gear­box are all okay in my bike, thank­fully. Strip­ping and in­spect­ing was easy thanks to the cas­sette-style gear­box, very ahead of its time in 1985 for a prod­die bike. I gave it all a good clean-out and re­assem­bled it, torquing ev­ery­thing up to ex­act fac­tory spec­i­fi­ca­tions.




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