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Manual for a bst40 carb11/19/2022 Skudd:- Perhaps she just thinks you are a window licker and is being nice just in case she becomes another Jill Dando. If you want to save the world, you have to push a few old ladies down the stairs. Sort the main jet, then the needle position then go from there. There is NO point fiddling with the mixture until you have the main jet correct. Get the idle mixture right before you try and sort out what is going on elsewhere, otherwise you will be going around in circles. The sooty plug may be the result of a far too large idle jet/idle mixture screw setting. The signs are pointing to trying a main of up to 150, but that seems enormous! Worth the few quid it'll cost though. The BST bible is a brilliant write up, that's where I got the float setting from! It appears to be the same for the DR650 though. The plug is quite sooty, but it's new and it's barely run off a rough idle, so I'm not reading too much into it yet. Sorry for the big post, any tips gratefully received. I've been playing with the pilot jet and mixture screw to get the idle reliable enough to start with, but I'm getting nowhere. The main and pilot jets are new and from a reputable source. The needle and needle jet are in good shape, not ovalised or worn. The float height seems to be OK, but the only guide I can find is for a KTM. It makes enough power to ride to 40-50mph or so, but needs coaxing to not cut out. I'm not sure what to make of this, as even quite lean or quite rich, with no load I'd expect to be able to rev it out. However, any fast throttle opening sees it cut out when cold, but with care when warm and about 25% throttle it'll slowly rev to 5000 or so, then seemingly hit a wall. I'm not sure about this as I'd think without the airbox the depression across the butterfly would be greater, and as such, more air should be passing through the pilot circuit.? I suspect it's rich, as it starts more easily with no choke, even when cold. It starts and idles badly, but just about manages it with persistence. However, I can't start with the main as it simply will not rev past 5000 or so, or use more than about 35% throttle angle. As standard it runs a 125 main and a 42.5 pilot jet. I've done some very light carb tweaking in the past, and it seems to be recommended to start with getting the main jet right, and working my way down to the pilot jet and mixture screw.įor reference it's a Mikuni BST-40 as used on the DR650, and KTM LC4 engines. I've removed the airbox, and fitted a Ramair sock filter, and now I'm trying to get it to run. I rebuilt it all, and got it rolling properly again, and now because I must, I started to tweak it. It was practically a non runner at the point of purchase, water had got into the tank, rusted it and the carb was full of muck. I have a Suzuki Goose 350 which I'm fixing up, modifying and playing with. Hello, first post, new member, and in need of assistance from someone with more experience.
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