Good stuff mate, maybe just a few tips though. It looks like the hone on that cylinder isn't really a cross hatch pattern. this is important as it provides better lubrication to the piston. also when installing the piston, just install it onto the rod first, and then push the rings in with your fingers and slide it into the barrel. This is much easier. But working on a bike like this is great to learn on since it's not a pricey mistake if things get mucked up, and they're also piss easy no power valves or anything. oh also you have great video production as well. Keep up the great work!
Thank you so much for the feedback! The cross hatch pattern is there, but it is indeed minuscule due to the honing tool that was used. The reasoning behind the method used to install the piston into the jug was for optimal camera view. This method was only one of three ways a piston could have been installed into the head on this motorcycle and was the most straightforward. It's always a pleasure, and we love hearing what you (the viewers) think. Until next time, - The Garage R&R Team
Where did you get parts for this old bike. I have a 1981 yamaha mr50 that I want to get running again. It has good spark new carb but it don't want to start. It's compression is 65 psi. But no play left to right or no play on the piston in the barrel. What should the compression be? Compression ratio of it is 6.9 : 1if it helps. On the piston it shows 1.00 does it mean it's 1 oversized? 41mm piston. I measured today Thx. Any help or suggestions welcome. Thx
Hello, If the head of the piston has been stamped with any number, in your case 1.00, this means the cylinder bore and piston size have been increased 1.00 over stock bore giving it an oversized piston. A loss of compression can be due to incorrect piston ring seating, scored piston, like what was seen in this video and the previous, or a bad head gasket can lead to compression leakage. The equation (Compression ratio x 14.7 atmospheric pressure) / 1 [(6.9 x 14.7) / 1 = 101.43 PSI] shows us that the engine compression spec is ~100PSI. Since your compression test resulted in 65PSI there is a compression pressure loss of 44PSI. Yamaha recommends at least 95PSI as the minimum compression pressure required for fuel ignition on two stroke motorcycles. I was able to obtain parts for my engine from Wiseco.com and then found my lower barrel/cylinder gasket from Partszilla.com and for my head gasket I searched through Ebay. If Partszilla or Wiseco does not have the parts you need they can steer you in the right direction. You've got a nice-looking bike on your hands and with a little patience and some faith, I'm sure you'll be enjoying it on the road in no time. Thank you so much for reaching out to us, I hope we were able to help you on your restoration journey, - The Garage R&R Team.
Jesus we pray for wisdom,don't hone dry make sure your piston size matches you didn't install circlips with your wrist pin and when breaking in use premix because your oil injection may need to be adjusted and it takes time to prime again.16 pds may have been a good torque spec. Also a letter or number on your rings faces up on the piston.
You are correct on all accounts. The hone was done with Flex-Hone brand honing oil on a milling machine (as seen in video). The Piston size is 53.50mm because the engine had been bored over 1.50 by the previous owners years ago. The circle clips were installed to hold the wrist pin in place and both rings were installed with numbers, stamps, or letters facing up following standard engine rebuild procedures. The proper break in procedure was followed after the initial fire up and before the ride (not filmed for viewers pleasure because it can be monotious) Royal Purple brand break in oil was used during the process. The oil injection pump on this motorcycle has been disabled and requires a manual premix in a separate tank before it can be added to the tank mounted on the motorcycle. Thank you so much for commenting and sharing your knowledge. - The Garage R&R Team.
I didn't see any oil when honing that's a messy job that normally would not be done on a work bench.If you installed the circlips fantastico but you may want to include that in your video or at least give a audio summary for the viewer. I like what your trying to do stick with it you have good editing and music and you are young with a strong blue spark.
@coolmonkeymc8268 Hello, so long as there is a consistent lubrication supply, (and you clean up the mess afterward) the honing as seen in the short three second segment of the beginning of this video caused no damage to the cylinder and provided sufficient cross hatching on the cylinder wall. The method used in the short three second segment of the video was done in a way to provide a clear viewing of a honing procedure on a small engine. Thank you so much for your feedback on this video, we will do our best to improve our content. Have a nice day, - The Garage R&R Team.
You may want to try your next assembly a little different .The bottom of your jug is chamfered for when installing the piston and rings I could go on but you may want to look at some DIY. Don't use a pic save that for your teeth.
Hello there 👋, being careful and patient when assembling any engine is key. We all have been taught different procedures, and learning new ones is always welcomed.
Good stuff mate, maybe just a few tips though. It looks like the hone on that cylinder isn't really a cross hatch pattern. this is important as it provides better lubrication to the piston. also when installing the piston, just install it onto the rod first, and then push the rings in with your fingers and slide it into the barrel. This is much easier. But working on a bike like this is great to learn on since it's not a pricey mistake if things get mucked up, and they're also piss easy no power valves or anything. oh also you have great video production as well. Keep up the great work!
Thank you so much for the feedback! The cross hatch pattern is there, but it is indeed minuscule due to the honing tool that was used. The reasoning behind the method used to install the piston into the jug was for optimal camera view. This method was only one of three ways a piston could have been installed into the head on this motorcycle and was the most straightforward. It's always a pleasure, and we love hearing what you (the viewers) think.
Until next time,
- The Garage R&R Team
Where did you get parts for this old bike. I have a 1981 yamaha mr50 that I want to get running again. It has good spark new carb but it don't want to start. It's compression is 65 psi. But no play left to right or no play on the piston in the barrel. What should the compression be? Compression ratio of it is 6.9 : 1if it helps.
On the piston it shows 1.00 does it mean it's 1 oversized? 41mm piston. I measured today
Thx. Any help or suggestions welcome. Thx
Hello,
If the head of the piston has been stamped with any number, in your case 1.00, this means the cylinder bore and piston size have been increased 1.00 over stock bore giving it an oversized piston. A loss of compression can be due to incorrect piston ring seating, scored piston, like what was seen in this video and the previous, or a bad head gasket can lead to compression leakage. The equation (Compression ratio x 14.7 atmospheric pressure) / 1 [(6.9 x 14.7) / 1 = 101.43 PSI] shows us that the engine compression spec is ~100PSI. Since your compression test resulted in 65PSI there is a compression pressure loss of 44PSI. Yamaha recommends at least 95PSI as the minimum compression pressure required for fuel ignition on two stroke motorcycles. I was able to obtain parts for my engine from Wiseco.com and then found my lower barrel/cylinder gasket from Partszilla.com and for my head gasket I searched through Ebay. If Partszilla or Wiseco does not have the parts you need they can steer you in the right direction. You've got a nice-looking bike on your hands and with a little patience and some faith, I'm sure you'll be enjoying it on the road in no time.
Thank you so much for reaching out to us, I hope we were able to help you on your restoration journey,
- The Garage R&R Team.
@@TheGarageRR thank you so much for your reply. I learn something again now. Thx for compression ratio formula.
Jesus we pray for wisdom,don't hone dry make sure your piston size matches you didn't install circlips with your wrist pin and when breaking in use premix because your oil injection may need to be adjusted and it takes time to prime again.16 pds may have been a good torque spec. Also a letter or number on your rings faces up on the piston.
You are correct on all accounts. The hone was done with Flex-Hone brand honing oil on a milling machine (as seen in video). The Piston size is 53.50mm because the engine had been bored over 1.50 by the previous owners years ago. The circle clips were installed to hold the wrist pin in place and both rings were installed with numbers, stamps, or letters facing up following standard engine rebuild procedures. The proper break in procedure was followed after the initial fire up and before the ride (not filmed for viewers pleasure because it can be monotious) Royal Purple brand break in oil was used during the process. The oil injection pump on this motorcycle has been disabled and requires a manual premix in a separate tank before it can be added to the tank mounted on the motorcycle. Thank you so much for commenting and sharing your knowledge.
- The Garage R&R Team.
I didn't see any oil when honing that's a messy job that normally would not be done on a work bench.If you installed the circlips fantastico but you may want to include that in your video or at least give a audio summary for the viewer. I like what your trying to do stick with it you have good editing and music and you are young with a strong blue spark.
@coolmonkeymc8268 Hello, so long as there is a consistent lubrication supply, (and you clean up the mess afterward) the honing as seen in the short three second segment of the beginning of this video caused no damage to the cylinder and provided sufficient cross hatching on the cylinder wall. The method used in the short three second segment of the video was done in a way to provide a clear viewing of a honing procedure on a small engine. Thank you so much for your feedback on this video, we will do our best to improve our content.
Have a nice day,
- The Garage R&R Team.
You may want to try your next assembly a little different .The bottom of your jug is chamfered for when installing the piston and rings I could go on but you may want to look at some DIY. Don't use a pic save that for your teeth.
Hello there 👋, being careful and patient when assembling any engine is key. We all have been taught different procedures, and learning new ones is always welcomed.