Topic: Tell me the secrets to cylinder boring

[geoluv]

My valve seal is leaking slowly on cylinder 3 of my '74 cb550k0.  Everyone is saying ignore it 'till it NEEDS a rebuild.  I am not fond of how it's fouling my plug.  I want to bore it because I've never over bored an engine before.  I ordered the cruisinimage 61.5mm pistons.  What do I need to tell the machinest?  Bore out to 61.5mm, hone, then deck?   Is decking nessisary with the 61.5 pistons if my cylinder faces are within spec? 

The softness of the jugs worries me.  Hondaman said he made a big ridged plate that he sandwiches the cylinders between to make sure they aren't getting warped when clamped.  I'm worried if I go to a machinest and tell them about the soft metal and the need for the plate to prevent warping they aren't gunna wanna do it. 

[geoluv]

Also if I don't have a ring grinder can I just very carefully use a dremel or thin file freehand or is that no dice?

[chewbacca5000]

For regular OEM style pistons I tell them I want a piston to bore clearance of .0012-.0015 and it works out great with my guy.  Make sure whoever you go to they have experience with motorcycles and small engines.  The tolerances for a MC engine is much tighter than a car engine.  If you just drop it off to a car only shop don't expect a good outcome.

[Jimray23]

My valve seal is leaking slowly on cylinder 3 of my '74 cb550k0.  Everyone is saying ignore it 'till it NEEDS a rebuild.  I am not fond of how it's fouling my plug.  I want to bore it because I've never over bored an engine before.  I ordered the cruisinimage 61.5mm pistons.  What do I need to tell the machinest?  Bore out to 61.5mm, hone, then deck?   Is decking nessisary with the 61.5 pistons if my cylinder faces are within spec? 

The softness of the jugs worries me.  Hondaman said he made a big ridged plate that he sandwiches the cylinders between to make sure they aren't getting warped when clamped.  I'm worried if I go to a machinest and tell them about the soft metal and the need for the plate to prevent warping they aren't gunna wanna do it.

If the machinist don't want to do it, you should probably find a different machinist. If its done wrong the first time then you have to resleeve at best, when boring that far.

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Jim
1979 kz1000b ltd
    stage 3 cams
    pod air filters
    4-1 open exhaust(no muffler)
    full rewire
    dyna-s ignition
    dyna 3 ohm coils

[geoluv]

^ i know thats the thing, cruisinimage offers 59.5mm pistons to fit this bike, or 61.5mm, nothing in between.  I wish they offered 61mm so you have room to go bigger later if something happens.  I just wanted to spend $150 not $450 for wisecos.  I got a real good deal on a whole 550 top end for $80 shipped so I'm going to port the head and bore the spare jugs while i ride.  Then ill have spare jugs in case anything arises.  also maybe ill port and do some valve mods on the spare head over time

The cruisinimage 61.5mm pistons and a spare cylinder is still less than half the cost of the wise or dynoman pistons. 

looks like the clearance consensus seems to be 1.2 to 1.5 thousandths?  and they don't state what material the pistons are but they are probably cast and machined.