rebuilding engine

[mechanickid]

so after a ton of trouble shooting and not getting anywhere i decided to rebuild the engine. ( see Head gasket questions tread )

any thing i should do while i have the engine apart?

 

[Bikeguy Joe]

Look at the inside of the cylinder for scoring, scratches, or burn marks. Same for the piston.

If you don't find anything, about all you can do to "re-build" one of these is buy a set of rings/piston, and/or a new cylinder too.

You can't bore them, you may hone one if you are exceedingly careful.

Exceedingly.

 

[stuartracing]

I just did a top end, if thats what tyou are considering a re build....Alittlec tough to get the rings in the cyl.`s, just take your time...Clean it spotless...OIL the needle bearing around the wrist pin.Port match anything while your in there...,intake port to piston,gasket`s, exh. and intake.....JMO....
Paul...

 

[mechanickid]

thanks guys.

im a bit new to engine mechanics and the language, where is the "needle bearing around the wrist pin"? what is port matching?

 

[mechanickid]

btw the piston was a little brown below the rings, what does that mean?

 

[stuartracing]

If you take the piston off the rod, you`ll see the needle bearins/in a cage...Just oil it up good...If you put the gaskets on their surfaces you`ll see they aren`t a perfect match to each surface....Just match up with a dremil...
Brown around the bottom of the rings is good oiling I beleive...

 

[mechanickid]

ah! thanks a lot, im going to go put it back together right now.

btw, when i went to robins auto part so get a ngk b5hs spark plug that they said they had in stock, but didn't, so they gave me a bosch equivalent. i asked them if it would burn hotter and they said it may a little. is that bad?

 

[Bikeguy Joe]

If it the "equivalent" it should burn the same or very close.
Brown below the rings can be blow by, which could mean the rings are shot.
Some engines don't have needle bearings up top where the rod connects to the piston, some have a bronze bushing.

 

[stuartracing]

If it the "equivalent" it should burn the same or very close.
Brown below the rings can be blow by, which could mean the rings are shot.
Some engines don't have needle bearings up top where the rod connects to the piston, some have a bronze bushing.

Aaah, learn sumpin every day,lol....

 

[mechanickid]

there was only a tiny bit of brown, and the rings were sealing very well.

it was nice to see that mine did have needle bearings.

btw, before i take EVERYTHING apart, do you have to remove the reduction gears to open the case?

 

[Dave31]

there was only a tiny bit of brown, and the rings were sealing very well.

it was nice to see that mine did have needle bearings.

btw, before i take EVERYTHING apart, do you have to remove the reduction gears to open the case?

http://motorbicycling.com/f30/bicycle-engine-total-tear-down-391.html

 

[fm2200]

I never heard of anyone getting away with puttting a new piston into a old bore, because the more miles you have on the engine the piston & cylinder wallls becomes egged and it's no longer round. And I guess it will run, but probably not last very long, BikeGuy-Joe says you can't rebore which is probably true. But what I do know, you must rebore to put a new piston in any engine. good luck with that fm2200

 

[stuartracing]

Who did that???

 

[Bikeguy Joe]

You can't bore a nikasil liner type bore.

 

[Bikeguy Joe]

You can re-ring an engine without boring. Just make sure you end gap the ring(s).

 

[Bikeguy Joe]

It's not the best way to go, but better than nothing if you can't afford a new jug.

 

[stuartracing]

It's not the best way to go, but better than nothing if you can't afford a new jug.

Not like it`s gonna start smoking or something

 

[mechanickid]

honing is quite necessary if you change the rings

 

[Bikeguy Joe]

Good luck honing a nikasil type jug. You may or may not get away with it.

 

[Bikeguy Joe]

Not like it`s gonna start smoking or something

Now THAT was funny.