Proceedure after rebore?

[Paul_Dublin]

One of my YAM 60's was down oc compression on bottom (of 3) cylinders.<br />Stripped down and discovered ring must have broken and smashed around so I ordered 3 oversize pistons, gaskets etc and got engine machine shop to rebore block. This is the first time I've rebuilt a motor. (just like building a big fire, I feel very manly!!).<br />Happliy it started OK, but I'm not sure if I have to "run in" the pistons and rings at low revs before I put it under any power??<br />I ran it for about 5 mins at tickover and then removed sparks and noticed some (Very fine) metal filings. As I completely cleaned the parts and deburred the ports I hope they are just the rings getting the sharp edges off? <br />As a precaution, I poured a few spoonfulls of 2 stroke thorough the spart holes and restarted the next day. Sounds good, but I'm not sure if I need to do anything else before I run it in anger?<br />Anyone done a rebore with any suggestions?

 

[rodbolt]

Re: Proceedure after rebore?

what did you use to clean the block with after the rebore?<br /> metal filings are very very bad. the rings dont wear in. it all fits together or it dies.<br /> good luck and keep posting

 

[Ray Neudecker]

Re: Proceedure after rebore?

Its not the rings wearing in. Did you clean block itself thourghly before assembly? Not much you can do now unless you take it back down, hone out the scratches and reassemble. The good news is I have seen this happen and run fine for years. Pray the metal doesn't get into the bearings and Good Luck.

 

[Paul_Dublin]

Re: Proceedure after rebore?

Cheers guys..<br />Basically I cleaned the block with a Fire hose, then dried with compressed air, then cleaned down with paint thinners, then air again to dry. I finally coated wiped everything off with 2 stroke.<br />The motor seems to run smoothly and it ran ok at idle but . I tried it under power for a few munites it struggled a bit. I'm assuming that this is becuase I put a very rich mix of 2 stroke into the fuel can (about 10:1). I'll clean out the fuel lines and run with a fresh tank of fuel.<br />Is there any issue with timing?<br />Will I need to get it checked or is it ok as the flywheel is re-alined to the drive shaft as per original setting due the the keyway?<br />Anything else I should look out for while running?

 

[Ray Neudecker]

Re: Proceedure after rebore?

Even though the flywheel timing hasn't moved, if the timing stop was moved during disassembly, it could be off and should be checked. That is way too much oil and you may have fouled your plugs. Change the plugs, check the timing and try again with a 50/1 oil mixture.