The only thing I could keep was the variator, flywheel, stator and the cylinder head. The rest went into the bin.
I don't think the 125cc engine cases are built for 183cc with high compression, 30mm intake valve 26 mm exhaust valve heads, fuel injection, a really good exhaust system, tuned for 180 cc. But it was a fast scooter til it died.
For the next engine I will try to get my hands on a B-case. Those are hard to find here in Sweden.
Speaking of exhaust, I developed a really good exhaust with Akunar in Thailand, they even namned the exhaust after my nickname "Wilds" GY6 Wilds Edition
Here's a picture of it when it's mounted on the scoot:
Wilds sorry to hear your trouble , I see what you post you seem to give more help then ask for it , I would question what and why the crank failed . I can not see pictures this morning , I can not see your pictures .
Well the reson I don't tend to ask so much for help is that I know quite a bit about engines... I used to play with V8s a lot when I was "young", a GY6 engine is much easier to work with but a lot harder to tune than a V8. The tune effects shows a lot better on a V8...
I would suspect that reson for the crank to brake down was some kind of material defects. It snapped right off at the red mark.
I was doing about 68 mph when it broke down. Luckily nothing else happened, I just rolled to a complete stop and pushed it off the road. After work I rented a trailer and got it back home and saw the damage.
I would show it to the vendor , and ask they forward that to where thy got it . This is a first on a stoker crank I have seen . I would hope that is not a common defect . If a part fails and is isolated to just that part being damaged , you can work with that . The crank seems to caused damage to other parts . You can't blame it on being lean or binding .
Yup, looks like you've overburdened the engine; seems like the overhead on those engines is lower than 33%; that's about correct with what we learned in mechanics class, 1/3rd overhead will create products that have a reasonable lifetime. Industrial products have higher % overhead.