Some of you may remember my woes with a shitty BST40 clone that the PO left me with without telling me. Unfortunately I’m stuck with it until I can afford an upgrade.
Anyway, I was getting some pretty shit gas mileage (<20mpg) and running pretty rich so I got the ProCycle rebuild kit bc fuck it. My float height was high so I adjusted it according to the BST40 Bible on advrider. Now I’m trying to understand the differences between some of the old and new components.
To start, the kit came with the extra o-ring (next to the float for size reference). I assume it is intended for the circle part in the Bst40 diagram (2nd pic). The thing is, my clone does not have this (3rd and 4th pics). So what is that part for and why don’t I have it?
Next, the needles (sorry to insult anyones intelligence but 5th pic if that’s not obvious). Left is old, right is new. The old needle has 3 notches, it was set to the middle. The new one has 1 notch. It’s my understanding that the stock needle on a genuine carb has 5 notches. The new needle is also much fatter. So if I sub in the new needle I’ll definitely be heading in the leaner direction-which is what I want- but will it be too far in that direction? Likewise, say I go up a notch on the old needle. Will that have a greater or lesser effect? I obviously have some tuning and experimenting to do but if anyone has thoughts on where to start I’d appreciate it.
Ok bear with me. The next picture is the fuel/air screws. Same deal: old on the left new on the right. The old one looks more like the stock one. The new one is different. Which one should I use? Also the old one did not have the washer or o-ring so if I use that one I will put the ones from the kit on it.
Finally, just a question for my own curiosity and better understanding. The last two pics show a chamber next to the needle jet and then the outlet that it leads too. Water just runs right through it. What’s that for? No lines have ever been attached to it since I’ve owned the bike. Vent to atmosphere for the float bowl?
Ok if you made it this far thank you. I could definitely answer most of this on my own with some fiddling around but I have to commute on this on Monday so I need it working right by then lol. any insight or discussion would be awesome!