1995 yamaha blaster
the problem: the engine makes a clear metal gringing sound when tring to turn it over. i thought it may be the piston but it looks ok to me(novice) when i pulled the jug both rings where in properly. i didnt see one out of its groove and ring gap was at the pin on the piston. on the jug i noticed a very small scratch but cant feel it to the touch. the scratch is on the carb side when engine is assembled. i checked the piston and rings where the contact point would be and cant see or feel any abrasions. i rebuilt topend 3 seasons ago. but about a month in rideing running good the rear bearings went so the bike sat for a few years. i fixed bearings and then tried to start it and suprisingly it started after just a few kicks. good gas and all before starting for first time. ohh i did mix my gas differernt this time. i ushally mix 32:1 but i mixed at 36:1 this time. slightly less oil. it was running rich before lots of smoke and seemed to hesitate a little. it seemed to start alot easier and i think it was because of the different mixture. so after starting so well i left the bike running for about 10 minutes. it idled very smooth and nice. before id have to rev it a bit to keep it idleing. then i got on and did a few circles in the lawn and it seemed to run well. lots of power compared to before if you gave it alot of throttle at once. so the next day i figured id take it somewhere to ride/work on it. got there and started it up on second kick. and let it idle for about 20 minutes. Again never ran this well and i think the new mixture is the difference. the idle did seem to hang so i started adjusting the air/fuel screw. out is more air in is less air. stock is 1 and 1/2 turns out from lightly seated. from stock setting i slowly started turning it out but only got worse so i turned it back to stock then started turning it in. i got it close to where i thought it should be. idle seemed to be jsut a little better. so i got on and rode it down the field and then i could tell it was starting to lose power and run different. i could hear a sound from the motor that sound like piston or rings was sticking or something. so i let it idle back most of the way back. but it was getting worse so i shut off the bike. it was a long push back. i got on it and with no intention to start it slowly pushed the kickstarter through it motion and can feel and hear so clear metal contact. so i read about all the things it could be but figured i wont know anything until i rip it apart. the only problem i see is the tiny scratch on the carb side of the jug. i know the scratch shouldnt be there but i dont see what caused it and what is creating the sound im hearing. today i took it all apart hoping to find out what the problem could be but the piston and rings look good and the clylinder looks good other then the tiny scratch. the rings gap isnt close enough to create the scratch. i was thinking maybe the rings came out somehow and created the scratch and the noise but they where in the gooves on the piston and appeared to be in the right spot with the pins on the piston when i pulled it. im putting the cylinder back on with the rings in correctly again to see if it makes the sound still. if i reseat the rings properly and put the jug back on i should be able to recreate the issue. if not then i think it could hve been the rings somehow. i have a few pics but cant upload them. i will try and post pics somewhere then upload them from there to here. i know i need to check the clearence between the piston and the cylinder wall and i know it should be less then 1mm. i dont have the tools to measure it.
the problem: the engine makes a clear metal gringing sound when tring to turn it over. i thought it may be the piston but it looks ok to me(novice) when i pulled the jug both rings where in properly. i didnt see one out of its groove and ring gap was at the pin on the piston. on the jug i noticed a very small scratch but cant feel it to the touch. the scratch is on the carb side when engine is assembled. i checked the piston and rings where the contact point would be and cant see or feel any abrasions. i rebuilt topend 3 seasons ago. but about a month in rideing running good the rear bearings went so the bike sat for a few years. i fixed bearings and then tried to start it and suprisingly it started after just a few kicks. good gas and all before starting for first time. ohh i did mix my gas differernt this time. i ushally mix 32:1 but i mixed at 36:1 this time. slightly less oil. it was running rich before lots of smoke and seemed to hesitate a little. it seemed to start alot easier and i think it was because of the different mixture. so after starting so well i left the bike running for about 10 minutes. it idled very smooth and nice. before id have to rev it a bit to keep it idleing. then i got on and did a few circles in the lawn and it seemed to run well. lots of power compared to before if you gave it alot of throttle at once. so the next day i figured id take it somewhere to ride/work on it. got there and started it up on second kick. and let it idle for about 20 minutes. Again never ran this well and i think the new mixture is the difference. the idle did seem to hang so i started adjusting the air/fuel screw. out is more air in is less air. stock is 1 and 1/2 turns out from lightly seated. from stock setting i slowly started turning it out but only got worse so i turned it back to stock then started turning it in. i got it close to where i thought it should be. idle seemed to be jsut a little better. so i got on and rode it down the field and then i could tell it was starting to lose power and run different. i could hear a sound from the motor that sound like piston or rings was sticking or something. so i let it idle back most of the way back. but it was getting worse so i shut off the bike. it was a long push back. i got on it and with no intention to start it slowly pushed the kickstarter through it motion and can feel and hear so clear metal contact. so i read about all the things it could be but figured i wont know anything until i rip it apart. the only problem i see is the tiny scratch on the carb side of the jug. i know the scratch shouldnt be there but i dont see what caused it and what is creating the sound im hearing. today i took it all apart hoping to find out what the problem could be but the piston and rings look good and the clylinder looks good other then the tiny scratch. the rings gap isnt close enough to create the scratch. i was thinking maybe the rings came out somehow and created the scratch and the noise but they where in the gooves on the piston and appeared to be in the right spot with the pins on the piston when i pulled it. im putting the cylinder back on with the rings in correctly again to see if it makes the sound still. if i reseat the rings properly and put the jug back on i should be able to recreate the issue. if not then i think it could hve been the rings somehow. i have a few pics but cant upload them. i will try and post pics somewhere then upload them from there to here. i know i need to check the clearence between the piston and the cylinder wall and i know it should be less then 1mm. i dont have the tools to measure it.
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