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has anyone Bored out a 85 honda spree?
Posted: Sat Aug 09, 2008 6:12 pm
by eddeblecourt
My cilinder is jacked and the only way to fix it is to bore it out 2 over. Has anyone done this before? Where would i find a piston? My local dealer said honda is out of stock. would i also have to rejet the carb?
Posted: Sat Aug 09, 2008 6:39 pm
by keithw
I just bored one to 3mm over. Found the piston on ebay. A 2mm piston is also available. Are you sure you need to bore it that far? Or is it the second overbore? That would be .5mm or .020". There is a Honda .5mm piston from another bike that works. The differance seems to be that it has a wider top ring so you need to make sure and get the correct rings.
The .5 piston is:
13103-GS7-305
The rings are:
13013-GS7-305
Once you have the cylinder off to do the rebore is the time to do a little exhaust port work. Raising the exhaust port about a rings width and opening it up between the port and the exhaust flange works wonders. I understand some bike shops will do this for a very reasonable cost.
If you burned up the cylinder you quite likely needed to rejet before. With a fresh cylinder you want to run it a little rich for a while to get it broken in.
keithw
Posted: Sun Aug 10, 2008 1:44 pm
by eddeblecourt
The clip that holds the wrist pin fell off so the pin has gouged the cylinder wall very deep. it is the first bore. how fast does you spree go after you bore? would a 43mm piston be the size for 2 over?
Posted: Sun Aug 10, 2008 10:07 pm
by keithw
Sounds like you need to start boring and see where it cleans up. Two mm over would be a 43mm piston.
The limit to how fast is goes is how fast the engine turns around. Mine pulled 11,000+ before boring and I don't expect it to go any higher and stay in one piece. With the overbore and porting the cylinder I hope to pick up some power so I can fiddle with the drive ratio and raise the speed.
A really handy tool for doing performance stuff is a clip on tachometer. The one I have can either clip over the spark plug wire or the wire going to the ignition coil. I made an extension for the coil low tension wire and velcroed the tach up by the speedo. The approach so far has been to derestrict till I got the engine to turn 11,000 then raise the drive ratio to push the speed up and the engine speed down.
I'm still breaking in the new piston so I haven't wound it up all the way yet.
keithw