Yamaha XT350 Rebuild - Bottom End

[JohnRaven.exe]

Hey all... Before I started this "little" project, the engine was knocking, making bad noises ect... The bike was ran on low oil for too long. I have ordered a new piston, rings, and head gaskets from the local Yamaha dealer. The piston was worn and scratched pretty bad.... and the rings were worn out. Now that I have all of the Top End apart... I was able to inspect the Bottom End a little bit. I was told by the dealer, that when this certain bike is ran on low oil... Its the bearings that usually go on them. The arm that attaches to the piston... There is slop in it from side to side. Is this the knocking noise I was hearing ???? or was it just the worm out piston??

BTW... I'm probably going to have the cylinder sleeve honed out by a professional... Its not nearly as bad looking as the piston was...

I just want to make sure I know what the problem is before I have to take the bottom end apart, which I am NOT looking forward to.

One more thing... this is my first bike, and my first rebuild. ( 1986 Yamaha XT350) Any tips and advice is appreciated!!!

 

[rerfurt]

I don't know anything specific about your bike, but in general you should get a service and repair manual, asap. This will tell you the acceptable side clearence of your rod ('arm'), along with everything else you need to know.

When you bring your cylinder in for honing, you might find that it needs one or two sizes bigger piston (The machinist will tell you), thus make sure you can trade your piston in for a bigger one, somehow.

If it was my engine that was run low on oil for any period of time, I would split the cases and inspect/renew the bearings, rather than having them fail regularly during the next couple of seasons.

 

[j32]

there should be a little side to side movement,but not up or down!!!!
hold the crank (flyweight),or out put gear-and pull the rod up and down,there should be no movment between it and the pin
you need a manual
?? do you need a extra seat,and rear fender??- i have one. let me know

 

[SRAD]

Hey all... Before I started this "little" project, the engine was knocking, making bad noises ect... The bike was ran on low oil for too long. I have ordered a new piston, rings, and head gaskets from the local Yamaha dealer. The piston was worn and scratched pretty bad.... and the rings were worn out. Now that I have all of the Top End apart... I was able to inspect the Bottom End a little bit. I was told by the dealer, that when this certain bike is ran on low oil... Its the bearings that usually go on them. The arm that attaches to the piston... There is slop in it from side to side. Is this the knocking noise I was hearing ???? or was it just the worm out piston??

BTW... I'm probably going to have the cylinder sleeve honed out by a professional... Its not nearly as bad looking as the piston was...

I just want to make sure I know what the problem is before I have to take the bottom end apart, which I am NOT looking forward to.

One more thing... this is my first bike, and my first rebuild. ( 1986 Yamaha XT350) Any tips and advice is appreciated!!!

Hi, check your plastick oil pump gear it can be damaged easly on XT 350 models.