Post by ausjock on Jul 23, 2020 9:07:47 GMT -5
I rescued one of these beasts from a scrapyard in mid 1980s. The engine turned over and had good compression so I thought there may not be all that much wrong with it The only missing parts were the oil cooler and barrel off the ignition switch, the key was in the tank cap.
Got it home and eventually started, it sounded like a cement mixer! stripped the engine down and found it had run the left crankpin bearing (big end) damaging the journal and the connecting rod. Had the journal metalsprayed and reground and the rod resized. Finding cranking bearings was a challenge, eventually we found that bearings from a renault 4 were the same size and with a bit of modification were pressed into service.
There was no internet in those days and I did not have any manuals so it was a case of put it all back the way it came apart.
Dragged it out of the shed now and then and took it for a run but the vibration was always pretty bad and it was a pig to start as the electric leg only made a rattling noise and I don't have a lot of body weight to turn it over.
Pulled it out again recently after a few more years gathering dust, cleaned the carbs and got it going, found this site on the web and perused the technical notices from Yamaha including the pictures of the adjustable balancer chain, "I think I've seen that lock washer under the gear shifter", sure enough I have an adjustable balance chain and I never new it!.
Adjusted the chain and much of the vibration disappeared
Also solved the starter problem (my post in the engine section), works great starts on the button, so I may use it a bit more now. cheapest and easiest mod. ever.
Got it home and eventually started, it sounded like a cement mixer! stripped the engine down and found it had run the left crankpin bearing (big end) damaging the journal and the connecting rod. Had the journal metalsprayed and reground and the rod resized. Finding cranking bearings was a challenge, eventually we found that bearings from a renault 4 were the same size and with a bit of modification were pressed into service.
There was no internet in those days and I did not have any manuals so it was a case of put it all back the way it came apart.
Dragged it out of the shed now and then and took it for a run but the vibration was always pretty bad and it was a pig to start as the electric leg only made a rattling noise and I don't have a lot of body weight to turn it over.
Pulled it out again recently after a few more years gathering dust, cleaned the carbs and got it going, found this site on the web and perused the technical notices from Yamaha including the pictures of the adjustable balancer chain, "I think I've seen that lock washer under the gear shifter", sure enough I have an adjustable balance chain and I never new it!.
Adjusted the chain and much of the vibration disappeared
Also solved the starter problem (my post in the engine section), works great starts on the button, so I may use it a bit more now. cheapest and easiest mod. ever.