Hello, im new to the forum. Ive been rebuilding a SUNL gokart its got a 4cly CHUOFENG engine that ive been told is 1000cc. i got the engine running the other day which is rad and am rewiring the gokart. The issue iam having is with the Transmission. there's a number printed on the trans BB200512A0109YH not sure if this is useful at all because i have looked high and low online to find any information about these transmissions and have come up short. all i have found is a couple sites that sell them for 1400 dollars which is insane to me. ok my issue if with the gear selector shaft and the mechanism which is housed under a cover beneath the trans. the trans works fine internally but when i shift the shaft gets stuck. i popped that cover off and everything in there just kind of fell out. I don't know exactly how its even supposed to go back together or if some part is missing causing it to no allow me to shift. iam provinding pics below. iam hunting for any information on these trannys. a model number? a parts diagram? a manual with instructions anything. or even a place that might sell them used or refurb for cheaper? its the last piece of the puzzle to getting this kart up and running again. any help would be much appreciated

Your engine and transmission is based off the Suzuki F series power train. All the SOHC engines in 650, 800, 1000cc use the same transmission, but some use a cable while others use a hard link for shifting. You will also find some use hydraulic while others use cable clutch engagement. The base transmission is the same on all these but there is some variation in gearing which I have never been able to decipher.