DIY Diagnostics

Hey gang,

So I was late for rehearsal. So I jumped on my beauty.
I thought I would save time and not fill up.
Big mistake.
Bike ran out of fuel. So I have been experiencing frequent carb-clogging lately due to a gastank-sealant experiment with por 15 gone wrong, and I thought that is why the carbs will start sputtering. It often means a clean is nigh, but it's also frightfully similar to what happens when you run out of fuel. And then you run lean for a bit, yark on the throttle, and the vacuum sometimes dislodges the particles and all is well for a (usually) lot longer.
So when I yarked on the throttle, i pulled the dregs of the float bowls' capacity up into the channel of vacuum through the carb, which ended up being far too litle, until i limped the block back home and shut her off.
And now my valves are a lot louder. The whole bike seems louder. AND it hard starts a lot more.
Here's what I think I'll find:
A bunch of valves that are not sealing properly due to either residue, or a burning. I don't know how pitted a valve can get, but I've seen some horrific pictures. It would explain why it's louder as it's not seating properly because the shape is changed. AND it would explain the struggle it has before it warms up AND, it would explain the other point that i missed, which is that the bike takes a lot longer to get warmed up, because usually i have to give it a little choke because something is out of whack with something and the bike has a tough time starting cold. THIS would be explained by the valves possibly needing more time to expand because of the fact that they're a little more worn. OR that could be the piston rings having the same issue, more expansion is needed to keep pressure in the cylinder because the rings got about 25,000 kms of wear in a coulpe of the cylinders which had enough of a fuel level to chug my bike back to my house.

That's what I think.

Let me know if I'm on the right track.

tl, dr: bike leaned out on a few cylinders because of running out of gas and yanking the throttle like a moron. This led to hard starting, longer warming and louder sounds coming from valves because of leaned-out pitting of the valves decreasing compression, or piston rings getting fried because of the lean mixture wearing on the whole cylinder chamber and beating on those rings. Am I right in assuming all this? Is this what I will find when I open up the bike with my sweet new socket set which I saved all month for?

Please share your wisdom,
Thanks

 

i rather doubt running out of gas killed your bike. Now that Por15 might have done your carbs, petcock and tank in but valves don't burn in the time it takes to run out of gas. The Sound is your imagination because we all know you check your valve clearance regularly. Right?

 

+1 It actually takes running very lean for quite a while to burn a valve.

Pull the carbs. Clean them.
Get some MEK to clean the bad POR-15 job out (you didn't prep the tank thoroughly enough or you would not be having problems with the liner).
Check your valve clearances, then do a compression check (more to ease your mind than anything).
Install an inline fuel filter so you dont' keep getting crud into the carbs.

 

You guys rule, I thought about it a bunch and it must've been my imagination (sorry, I'm literally out and about 24/7 and I have had no time to work on the bike)
The sounds are louder, but it's an old bike, so I'm not really surprised.
What is concerning me is the fact that it'll start up fine, then all of a sudden as it warms up, I'll get to a red light, and slowly the revs start to fall, until it'll get to the edge of life and I'll have to pll the throttle open a touch to get it going. I don't imagine fuel levels in the bowls would change over time, so it shouldn't be that. I WILL be getting new throttle shaft seals as a precautionary measure in any case, but I'm really not sure why she won't hold revs anymore. I JUST cleaned the carbs, fully, every passage, polished the pistons, but I think i may have a hole in one of my pod filters, so I'll go over those right now.
Thanks for your continued wisdom, gentlemen.

 

Is the petcock allowing good fuel flow at idle - the vacuum would be lower. (Now I'm speculating...not an expert).

 

That is either overheating (unlikely), or fuel delivery.
DO NOT ASSUME that things are correct in the carbs, INCLUDING the fuel levels. Double check your work, and verify that things really are set up correctly.
I used to be a service tech (industrial machinery) and if a machine started acting up following maintainance of a system (problem within that system; i.e. failure in a gearbox that had just been serviced) the first thing that I was taught to suspect was the work that had just been done (even if it were my work). Most of the time that was the cause of the trouble; some little thing that had been missed, or a clue to an underlying problem that had been overlooked the first go-around (everyone makes errors).

 

Ooooh... okay so Petcock. I have an in-line fuel filter which I plugged in when I was tired of constantly cleaning carbs because of a rusty tank. It's see-through, looks fine, but could be the problem. Expecially since after the POR-15 incident it has been worse.

It piques my curiosity because as a beginner (as if I'm not still a beginner) the bike would sometimes die at reds. This could've been a combination of problems, but the only thing I knew to do at the time was the only thing within my reach when I was commuting somewhere on a schedule: Turn it to "prime". It would only start again after a certain amount of time sitting and priming. I assumed, like k-moe has said, that by disassembling the petcock and cleaning it, reassembling it carefully and determining it was sufficiently normal-looking that everything was done well.

I really respect that advice, by the way, K-moe. The most important lessons restoring and renewing this old motorcycle has taught me have been patience and humility. And I can admit when I'm wrong, and I must, because my mistake may either kill me or take my fun on two wheels away. There's no denying it when a piece of piston ring breaks and falls into the crankcase when you're putting jugs back on. So it's not that I have a naive confidence that my work was flawless, what I wanted to do from the beginning was see if I can diagnose the issue from a bit of a distance, therefore saving time and valuable resource. It was in no way a hope to short cuts. I know I'm far from a mechanic yet.
Though my carb cleaning is becoming ever more rapid and efficient (and of course, thorough).
Thanks again, Y'all