With the bike in top gear and the rear wheel off the ground remove the spark plug and place a drinking straw in the hole to help you confirm TDC. The easier way is to take advantage of the sight glass on the stator side of the engine. Rotate the rear wheel-still in top gear until you see a plainly visible notch in the flywheel as you shine a bright flashlight into the site glass. Dirty
It was definitely TDC with spark plug out etc. I had to move it slightly off of the notch to get the valves to go slack. So WTF. Damn
That's pretty extreme. Yep, the BST is notorious for needle/jet/slide/slide-guide wear, but if all those parts are new it should stay good for a lot longer than 5-6 thousand miles. Mine has had only the needle jet replaced at 40,000km (should have been 30) and now has 50,000km and runs sweet as. I will probably replace all the aforementioned parts at 60,000km. This seems fairly typical; a far cry from replacement every 8-10,000km as you suggest. My slide and guide appeared "scuffed" but not "grooved"; that is, nothing you can catch a fingernail on. If you are getting that kind of wear, then perhaps start looking for dust ingress.
My bike ran great at 26,000 miles, but the parts showed wear, so I rebuilt the carb with new slide/guide/emulsion tube/needle. Those parts may have been replaced before I bought the bike, but they had been in there for at least 12,000 miles. My bike isn't a dog, either, and it gets around 50 mpg. . . running a significantly larger main jet than most on here, apparently (now I can't remember what it is, I think it's a 162.5). Works for me, so I'm not changing it.
Not that much dust, you may be right, I often ride alone, and 50/50 street/dirt. Derek, the Motolab guy who is a BST guru, reports that carbs with the slide holes drilled out larger will wear much faster- not sure if your carb has that. Asking these questions in the big BST-40 thread may get some more views/opinions.
FYI all. I have some 04 625 SXC parts over on Flea Market... I want to thank all the LC4 people who have helped me with my SXC over the past couple of years. You guys in this thread have been invaluable and so helpful. Unfortunately, my SXC was totalled and I am not riding anymore. maybe we'll cross paths some day in the future. It's time for me to learn how to surf...
Sorry to hear your bike was totaled. I have two that I couldn't replace with new if they were crashed, the LC4 and SD.
My cam roller bearing just failed, need a new one of those and a new cam. Still got me home, or at least to where my buddy picked me up.
no idea? I don't recall other people having this issue, but if you run into anything weird doing a valve check then have a look at this. I haven't had anyone else pop up to make more comments yet either.
Does anyone know how many needle bearings are in a cam roller? We've found 14 so far and don't want to miss any before putting it all back together, does it make sense to replace both of them while the motor is open?
As reliable as my LC4 has been, from what I hear and see sometimes I wonder if my bike isn't just biding it's time and waiting to strand me far from home. My bike has been incredibly trouble free so far, and great to ride. Should this I worry about this? Trade for a BMW, so I know that only the final drive will fail? Or just figure that everything with moving parts wears out eventually and keep riding?
:huh Cam follower roller bearing failure (usually the inlet IIRC) is one of the most common major issues with the LC4 mill. The water pump would be the other. Keep on top of these 2 & I would guess most well looked after LC4's would make it north of 80K km with little other work. My first set did 50K km before the inlet was worn out, (got lucky & caught it at a valve check) the 2nd set were ok after another 45K km but got replaced anyway during a big rebuild. The current ones will be replaced after 40K km to be sure. I have heard of others failing at less but not too many. The water pump needs doing at about the same mileage & the main cam bearings are so cheap that you may as well throw in a new set of those too while you're in there. Cheers Clint