gs450 - still not running right

[bren]

yea, i will tomorrow when i take it back apart. i took video of it but my video cam refused to focus on it.

here's a video i made of todays carburetor adventure.

engine run starts at around 4 minutes. i ran it from pretty much stone cold until it was fully hot.

[bren]

Well I figured it out finally. I took the carbs back off to swap another piece. Only a couple things left to try - the bowls were gonna be next. But I just sat there for like an hour, looking through it with the bowls off and thinking about it. Following the passages. Spraying carb juice through it. And it was totally pristine in there. I couldn't think of a single reason why it shouldn't be working.

So I finally just stopped. And I thought, I have to be missing something. I already went back to step 1 and started over on cleaning the carbs, to no effect. So I went back even further to step zero.

I set the carbs on the table, went back inside, and started doing a bunch of research on how cv carbs work. Trying to understand them in detail, troubleshooting them, tuning them, etc. And slowly, a realization started to dawn on me...

The bike is already fixed. It's already working perfectly, doing exactly what it's supposed to do - given the inputs that I'm giving to it. It wasn't that something was wrong with the bike - it was actually that I was doing something wrong with it.

So this morning before work, I had just enough time to warm the bike up and tweak things a bit with my newly gained knowledge. I've had both mix screws set at 2.5 turns out, which I read on here was more or less standard practice, and just kind of accepted that uncritically. I took the carb that was running hot and turned the screw out some more, and it started running different. Kinda wonky - but different. So - one thing I learned last night is that if you close the mix screws, the bike should shut off. So I did that - and when it kept running - I realized what I'd done. The idle was set too high, because the pilot was set so lean that the butterflies had to hang open and pull fuel from inside the venturi to be able to idle. Now, closing the pilots made it immediately start getting super hot, so I quickly turned both mix screws out maybe 4 or 5 turns and dropped the idle screw much lower. Suddenly the idle sounded a ton better; strong, steady. the vac gauges also started pulling way more vaccuum. And finally when I blipped the throttle, it came right back down, just like it should. I couldn't believe it. Just like that. All this time, and I fixed it just like that.

So the bike was indeed running very lean - but it wasn't her fault, it was my own basic newbie mistake. I simply didn't understand how to set the mixture and idle screws, and didn't understand the carbs in enough detail to really troubleshoot properly.

my mind is really blown by this revelation. I thought it would be some kind of grand eureka moment when I figured out this problem, a moment of elation. But in reality, the truth kinda hurts. And machines don't lie.

While I feel very relieved to be finally past this issue, I also feel pretty sheepish about it. I've done so much tinkering and working on this bike, blood sweat and tears, trying different stuff, changing parts and what not, all on a perfectly running bike that was simply misconfigured. I mean, some of the stuff it's probably good that I changed it out, like the new carb boots that are nice and soft. I don't even regret upgrading the ignition, I've wanted to do that from the start anyway and just needed an excuse to pony up for it. But man. To think that three little screws are what kept me from riding, for months.

But what can you say. I guess it's just the cost of tuition. I can't be mad about it, I just gotta think that the knowledge gained is worth a few months and 500 bucks worth of fixing what ain't broke. That's half of the reason I bought a 40 year old bike in the first place. But now I can finally get started on the other half - actually riding it.

Anyway, the help on this thread has been appreciated.