I would double check your compression tester, measure ring gap, whilst apart make sure you change the powervalve seals, and do a leak down test, nice bike btw, good luck👍
Oh yes … compression is rubbish, actually ordered a set of rings for my own curiosity to see what she has lost over the years …. And you go for ya feeler gauges and hay presto … not there …. Anyways fun and games in old bikes … thanks for the reply
@@joenielsen68 Hey Joe, Sounds like you have got it under control.😉 You are going to have a very nice YPVS when you are done. Good Luck with your project.
40 year plus RD owner here. Your bike looks like it has been running lean. Check the jetting and cleanliness of the carbs. Cylinder bores and pistons show no signs of seizure or piston rattling. Your compression is way too low. 125 psi or higher is your goal. Measure your pistons and measure your cylinders with a bore gauge. Fore and aft, as well as side to side 10mm up from the bottom, mid stroke, and 10mm down from the top. This will tell you how round your bores are. Depending on your measurements, you may get away cheap with a hone, or you may have to bore .25 over. If your measurements are good enough for just a hone, I'd spring for piston kits and small end bearings. I would not reuse those toasted pistons. Not worth the risk. Also, plan on doing a leak down test on your engine. It will give you a very clear idea of the health of your crank seals, head and base gaskets, and carb boots. You can put together a hardware store testing set up for about 12 to 15 pounds sterling. No need to spend crazy money. 6 to 8 psi for 15 minutes is your goal. Finally, replace the o rings and castle seals in the PV while you have the top end out. Last bit , Yamaha head gasket only! By the way, that is the cleanest 39 year old bike I have ever seen! You have a good base to build on, but 39 year old rubber parts need to be replaced. Good thing is the parts are available. Take your time, plan it out, and do it by the numbers. It'll come out great. You can do it.😊
That to everyone out there is the kind of advice everyone should read, if you don’t take it on board your silly but sound perfect advice , most of what has been done already , head honed with 15 seconds and perfectly round no uneven wear on the cylinder with measured rings old and new , unfortunately for the test I’m running before complete rebuild I am using old pistons but only for a start up and tests then strip rebuild on bearings seals etc, also testing 2 stroke consumption,cylinder has new seals and rings for this test …. But thank you so much for your time and reply it is the likes of you that help everyone out there Videos to follow will show my results
Ahhh and one more thing , after reading your comment I nearly forgot the leak test pressure….. low psi not sure why I forgot that …. Complete rebuilt is the way as even if it holds pressure the runners and seals are old as this motor has never been split
