littlebasher Posted January 25, 2014 Share Posted January 25, 2014 When I was 17 I bought a RS125, after one week the alloy gearbox casing was punctured after the clutch exploded. The casing price was astronomical at the time. I had to order the clutch parts from Italy which took several weeks to arrive. I had the casing alloy welded and then spent hours sanding it down on some sheet glass so it was level. Rebuilt and sold a few weeks later. This was the 'original' rotax engine. I had a c50 and fitted a c90 barrel and head and the thing flew! At the time my mate had a brand spanking italjet dragster 50cc and it used to show him up all the time on the hills :-) Just remember that most 50cc are 2 strokes and they've probably been thrashed within a inch of its life! Make sure it's got some service history (probably very rare) and if you buy private, you'll probably bd able to judge the character of the seller. IIRC only the C70 barrel and was a straight swap with the C50 as they shared the same crank. C90 used a different one. Link to comment Share on other sites More sharing options...
GRUSS Posted January 25, 2014 Share Posted January 25, 2014 IIRC only the C70 barrel and was a straight swap with the C50 as they shared the same crank. C90 used a different one. You are correct my friend, I found this out when I put it back together and tried to kick it over! It locked solid after the valves fouled the piston! The older blokes at work had an idea though! They 'carefully' ground pockets into the top of the piston and shaved the crown to allow the valves to open. I was 16 at the time (31) now so it's a little vague. I also seem to remember having to fit a c90 exhaust as the exhaust port was a lot bigger. No idea of the compression ratio but on the original c50's twist and go gearing it was a bit if a animal! Link to comment Share on other sites More sharing options...
littlebasher Posted January 26, 2014 Share Posted January 26, 2014 You are correct my friend, I found this out when I put it back together and tried to kick it over! It locked solid after the valves fouled the piston! The older blokes at work had an idea though! They 'carefully' ground pockets into the top of the piston and shaved the crown to allow the valves to open. I was 16 at the time (31) now so it's a little vague. I also seem to remember having to fit a c90 exhaust as the exhaust port was a lot bigger. No idea of the compression ratio but on the original c50's twist and go gearing it was a bit if a animal! I went the other way and stuck the reg plate, front badge and stickers from a C50 onto a C90! Earlier attempts to shoehorn the larger C90 engine into a small C50 frame were not very successful! Link to comment Share on other sites More sharing options...
pocket Posted January 26, 2014 Share Posted January 26, 2014 How about a Honda monkey bike great little bike I still ride one can't go wrong lol Link to comment Share on other sites More sharing options...
GRUSS Posted January 26, 2014 Share Posted January 26, 2014 How about a Honda monkey bike great little bike I still ride one can't go wrong lol Had a couple of monkeys a few years back. I put a 150cc in one and the 1 fell off the barrel ;-) Link to comment Share on other sites More sharing options...
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