just picked up a new in the box 4mm marine crank and 5 new stk rod length custom je 3mm stroker pistons, also ape hd head studs. all for $600 from my friend cooper performance. my gen 2 engine, head has just had a cnc vj and freshened up.it wrapped up/assembled ready to drop on. my first stroker ten, but not my first from scratch stroker build. head off, one bolt holding engine in frame, so strip engine/boring/plating soon in december.i will be doing build, have tuner.
my base is 193/87 ft lb torque with stk pistons, race int., stk ex. cam. using same dyno/tuner different fuel.deciding on cam selection now. head fitted with stk 30mm int,, larger int being considered also.think the hp will be there, really more concerned with torque band.
Dyno, shmyno.... that thing is going to be an absolute monster from about 7K to 12K, I'd put money on it right now. Better start shopping for smaller rear sprockets now.
true that. been screaming this stk piston combo with 15/42 in the 1/4. rev limit at 14k, reason looking for big torque to keep rpm's down to liveable level. starting with 17/43.
top case at millenium being bored/plated now, been there 2 weeks, quoted me three to finish. rods headed to kim at carolina cycle with new bolts/nuts to install and to be checked for roundness/resizing.bought a pristine used set of cases im using, old cases had a cylinder head bolt hole stripped. just finished yesterday inspecting/ transferring all bottom case internals into new bottom case. so top case back, gap the rings, measure main/rod bearings, button cases up. basic engine ready this month.
recieved my pistons and bored/replated top case back yesterday. wrist pins moved up 2mm on piston to allow stk rod length, and short skirt design. stk 76mm piston weight with rings/wristpin is 235.2 grams, new 79mm je pistons complete at 245 grams. je pistons also gas ported to help with ring seal. finished gapping top rings at .013, 2nd ring at .017. also using carpenter 397 lift intake cam. soon as rods back, rod/main bearings selected and cases assembled.
Nice, JE have a second compression ring on a -2mm piston?? What code are the pistons i thought they only did a single ring on a -2mm piston?? This is good news for me.
michael the pistons are etched 643820 on the wristpin boss. use std 17mm wristpin with 3 ring pack. searched je, googled part number with no results. came from jerry at cooper performance, he said custom made. has a lot of pistons/cams made to his specs.
only two things left on build, had new rod bolts/nuts installed and rods resized to be perfectley round, now have to measure main/rod bearings to use, also head having 31mm int valves installed at cooper perf now on his cnc machine. single blade ceramic cutter goes in cuts a 70 degree cut to the port seat match opening out the throat, finishes the custom top angles.choose to stay with 25 mm ex for torque, not building a high rpm engine as last one . combustion chamber not stk, previousley milled to the max. cc'ing the head 31 valves installed, may have too much compression, also have a ton of work on other bikes progressing along with. plan to make the mancup race early may.
no the stk gen 2 seat inserts are fine for 31 valves.been busy with other builds not taking much in right now, planning on finishing engine in march, tuning on dynol 832 for fuel.
the .45mm/.018 head gasket alone usually sets the pth .026-.28 and is easy to do. piston deck height stk on these motors -.008-.010. some run a little tighter, this is safe and pistons almost kissing head at highrpm as carbon on head deck stays clean on inspection. i also mill these heads .015-.020 street/.025-.032 race. tight pth always on these motors makes power.
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