I am really glad that I watched this video I have a kx125 and I just tore it apart,you can watch my video that I just put out. I was going to replace the crankshaft because I thought that much play wasn't normal, turns out my in-and-out play is 0, so it's perfect all I have to do is clean it and reassemble your awsome.
I have a gauge attached to the engine. I'm going to try to rebuild the engine. I've never done it before but I have the Clymer's manual. Love your video. Helps a lot. thanks!
Why do You think the bottom end side to side play is excessive ? It's absolutely fine in my opinion. I think it's even better to suck some extra oil from sides. once it's rolling fast it sets on the middle anyway.
well my crank went about 2 week ago that was not fun but today i just got a new hot rods crank, and the old one like the bearing basically doesnt exist
I bought an rm125 and put a brand new crank rod and bearing into it. Put it back together and rode it an hour. New top end too btw. After one hour I popped everything off again just to look and make sure the cylinder head was ok because there was some blow up chunks from before I bought it. Noticed there was quite of bit of loose play in the crank rod after ONE HOUR OF RIDING. I put it back together. I've put about ten hours on it since. Still rides great but I'm gonna go ahead and get a new bearing ordered.
ok... i am facing a strange vibration and sound at very low rpm (idle nd below idle). The sound nd vib vanishes when the engine is revved..my engine is Yamaha meke 4 stroke Sohc single cylinder. have done 26000kms. Any idea what might have happened? i am suspecting a worn connecting rod bearing. Thank you.
I have a 1978 cb750F SOHC4. I found metal shavings in the oil pan and they stuck to a magnet. Someone told me that it might be from the damaged bearing. I'm also experiencing loss of oil pressure at idle when warmed up. So much drop in oil pressure that it dies at red lights. I had a tow truck bring it back home and have not run it since. Any help would be appreciated.
I just purchased a 2000 Rm 250 for 450.00 and the guy I bought it from was concerned about the crank rod because it has a little play from side to side but up and down it moves a lot so I figured it would be better to just go ahead and replace the crank rod and bearings because I don’t want to ruin the brand new piston and rings
Question the crankshaft is in middle on one side is clutch and on other side is the thing that generates electricity and so crankshaft is in middle of there?
Actually i am hearing a grinding/rubbing noise from my bike's engine at idle and low rpms ... the sound increases with drop in RPM. The engine is YAMAHA make 4 stroke single cylinder SOHC engine. Any ideas about the symptoms ?
Hi JG, I had a partial seizure of my bike it was like the breaks had been slammed on for a brief second. The bike then freed it self and I was able to limp home via the back roads. The seizure was caused by low oil and after striping the top end down. Found that the piston and cylinder were badly scored on the exhaust port side. My concern is that I have done some damage to the big end bearings is there any way I can check for wear while the cylinder is of and the crank exposed as in your video.
Hello i have a Question for you, if the rod is not freely spinning on the crank, does this mean the crank is bad? If you check the video on my channel, you can see a better example
if the bearing is bad as shown in the video, is it ok to change just the bearing rather than the rod, pin & etc? and how to check the piston pin bearing? and how does the knocking sound like?
some two cycle have crank case oil like some is lubricated with gas/oil mix these KX YZ RM CR are all lube by gas/oil only 100% no crank case oil, but Yes some 2 stroke have crank case oil both right.
Nope they all have to use the premix oil .. no 2 stroke has ever used crank case oil because it will foul out plugs and make the bike run horrible and not to mention it will eat up all the transmission fluid or oil very quick
hi I have a 1994 Suzuki rm 80 im changing the whole top end on it... I can move the rod side to side and there is about 5-8mm travel on the roller bearing ... think I can reuse the bottom end that way? there is absolutely no play up and down... please answer me
@@jenniesgarage definitely not true bro I know you said this 5 years ago but side to side play can and will eventually let the crank needle bearings slide out past the thrust washers and there's your top end I have installed many cranks and ever time the crank go side to side play they would throw the needle bearings in the rod it self and a damage my cyclinders ....
old comment but to fix rod bearings you have to buy a whole new crank and split ur cases and press the old crank out and put the new one in. big pain in ass
Ok the side to side to play is at. .018 to .025. When you get a crank back a new rod. Any up and down play you should have a new rod put on. All the oil that I saw in the crank case tells me that he has a crank seal out also.
I bought an old two cylinder two stroke. The side to side in both rods is about as it is in this video. There is no up and down play so I should be good?
mike hawk no it will not eventually you'll get a rotational whining noise that increases and decreases with rpm.....then like he said catastrophic failure.....if you have a knock......you need to pull it apart and find signs of heat and friction...blued metal is overheated dead metal
@@brokebikemtb4448 so your saying half my crank is overheated? Half is blue and half is almost a polished finish.. what does it mean? Bought the bike a month ago, noticed a knock that is getting worse, pulled the head, scoring on piston and minor scores in the cylinder from an improperly installed air filter (no probs.. big bore), the bike was oil injected however the previous owners were still running premix with the oil pump connected and working. Any ideas?
Yee Thirty play between piston and cylinder, otherwise known as piston slap. Need to see if bore is still in spec(probably not)... fix it before it shatters the piston skirts. Check big and little end clearances while y0u are in there...
Lavert Powers Nope, unless you have the world's tiniest hands and can get the world's tiniest socket wrench in there. You're gonna have to pull the case apart for it.
Tell ya what...ill watch u guys...just ran into a shit load of tools strickly for go karts and bikes and ect. Aint nothing but time...trust me..I got three motors here....one will become one...lol
AWFUL description--- END PLAY is how close the crank halves are to conrod journal. RADIAL END PLAY is how much the rod ROCKS like a clock pendulum SIDE TO SIDE.---- YOU PULLING is only going to show anything when conrod has over 5 thou WEAR. and will be NOISY before you ever feel it.
My 80 is fucked, tippity tapping and by quickly turning the flywheel back and forth you can hear that terrible noise, fuuuuuuck i hate balancing cranks
clearly wrong about what is right and wrong. what is and what is not acceptable. use service limit and prove your case. FEELER GAUGES. sorry but that is the way it is.
my aprilia RS125 conrod has massive side to side movement and no up and down. This tells me the thrust is out badly, then its time for a rebuild. more left than right movement puts strain and excessive movement on the top end boring more damages both to cylinder piston and rings. Hence not totally right. I found out the hard way using your method. If you're going to do it right, then do it right first time. again sorry but that's the way i'm built, had my hands burnt too many times, maybe I should also quit cooking. :P but nice for you to reply, thank you bud. However, I would like your input about specing the engine rebuilds and maybe covering a topic or 2 with a before and after built of a running engine - along with parts used. Be a good way to put this to bed I guess.
Imo he made the video not about side to sise play, but up and down.... he said no play should be noticed up and down. he was talking about All BIKES, he probaly don't want to look up every motorcycles side to side play and list it..
You can tell it’s toast by looking at it with the human eye, heat marks the rod looks twisted too. Please don’t make “how to” videos when you clearly don’t know nothing. Good day.
