47000k, never adjusted valve clearances

[Agebot]

Hey guys,

This is entirely hypothetical, so save any judgements for your hypothetical bike abuser and definitely not me.

Lets say you'd bought a bike new more than a decade ago and had done everything but tire changes and a new chain yourself. Had followed all the scheduled maintenance in the Haynes book, bar one minor detail.

You'd never taken the valve cover off and adjusted the valve clearances.

Your hypothetical bike abuser is in a lockdown and may finally have time to measure shims and and order replacements before the commuter bike is needed again. Had also been hearing a slight metallic tick with each turn of the engine for the last couple of thousand k's, particularly at low revs after warming up. And the bike was a little bit gutless, the exhaust had started reeking like an old Datsun, but was coming out clear.

To minimise down time and order as many needed parts as possible, what problems would you expect to run into when taking the valve cover off?

I'm expecting the gasket to have hardened to the point of needing to scrape it off by now, but what other problems would our hypothetical bike abuser be likely to encounter?

Age

[mr72]

The gasket is rubber. You should probably get a new one anyway due to age alone, but it is not going to require scraping off. It fits in a channel.

I suspect you will find no gross problem with the valve clearances. If they had tightened enough to have an effect, you'd have a burnt valve by now.

[The Buddha]

A valve going tight to the point of needing adjustment would start up fine but within 5 seconds of startup want to stall and wont run unless you revved it till it got fully hot.
A valve that's out of spec loose will make a lot of noise and not neccessarily cause any problems.

If you had the first and ignored it for a long time, you'd essentially lose that cyl whenever you shut the throttle.

I'd say if you're not having these symptoms you could likely just measure them and not have to buy shims etc to adjust.

Cool.
Buddha.

[Agebot]

Still waiting on a replacement gasket and o-rings before taking the valve cover off.

Made the mistake of thinking it'd be a one day job to re-jet the carbs.

Got one screw off with vice pliers.

Torn the rest to shreds with easy outs and chipped a flathead trying to unscrew one I'd slotted.

Thinking it's time I bought a car.

... And the wrong carb rebuild kit.

[mr72]

what screw could you possibly be having trouble with getting the carbs off? I mean, there's hose clamps on rubber boots on both ends of the carbs. I hope you are not talking about destroying the float bowl screws or the diaphragm cover.

[Agebot]

This bike has lived outside for 12 years, but most of that time I was living in a fairly dry area. The last two in a wetter climate have just massively accelerated corrosion and I hadn't really noticed it on anything other than the chrome parts until now. I put gaiters on my forks when changing the seals and called it a day, but this is the first time in three years I've taken the tank off.

The carbs are now fairly well dusted with white corrosion, and every single screw is stuck.

So... yes. I am absolutely talking about destroying all eight float bowl screws, three of the four diaphragm cover screws and even one of the two screws that mount the vacuum solenoid to the bottom of the right carb.

I have a precise little heat gun for SMD soldering that's normally great for removing stuck screws with WD40 and some easy outs. No such luck this time.

I had read on gstwins that these screws could be problematic when I bought the jets a few years back and got a full set of stainless steel socket headed replacement bolts at the same time. I've slowly used about half of them in random projects over the last few years, but I was not expecting literally every single bolt to be jammed. I'm going to have to drill the caps off and hope I don't do any damage. Any more damage than I did f%$king around with vice pliers and a little slotting hack saw. Should be easy enough to remove the remaining studs with vice grips.

I was hoping I could get away with a fairly minimal disassembly. At this point... I feel like the whole assembly needs to be soaked in vinegar and scrubbed before I even try taking it apart.

And with everything out of the way I can see that my valve cover looks just manky as hell. I'm assuming it's aluminium with a zinc paint as there is corrosion that's coming up underneath the 'paint' or galv, whatever it is, on the valve cover. If you scratch away the blistered coating there is the same rough calky corrosion under it as on the external surface of the carbs. Crankcase breather tube also seemed to be clogged with some kind of petroleum wax and water, and the breather assembly on top of the valve cover is even more corroded.

This isn't looking like a quick weekend tune up anymore.

[mr72]

Well sounds like you are well along the process here but for future reference, reverse drill bits work wonders at pulling out these types of screws. Usually they are not really stuck because of corrosion, they're just stuck because of different expansion rates of the aluminum part and the steel screw which causes it to have a ton of clamping force holding the screw head. This can go very badly if you use the wrong type of screwdriver, which BTW I have done a thousand times without a second thought, but on my recently acquired Yamaha Vino, the brand spanking new carb cap screws will absolutely not budge and a standard Phillips screwdriver is going to ruin the screw heads if I try to remove them with it. Everyone complains that "Suzuki" used soft screw material but this is Mikuni's fault. Indeed they are somewhat soft, but also the problem is you can't put enough downward pressure on it to keep the Phillips screwdriver from slipping and the Phillips screwdriver is likely to slip in a JIS screw anyway. So sometimes that JIS screwdriver is warranted. Sometimes a reverse drill bit is the only way. Makes me really glad for my Triumph's abundant use of Torx screws.

The corrosion under the paint is just regular aluminum oxidation, which I have noticed is prevalent when exposed to ethanol in gasoline. Even my custom-made aluminum foot peg brackets are corroded like this due to a tiny fuel leak above one of them from the petcock. This is probably not what's causing those fasteners to stick, though.

I always try to soak stuff in PB Blaster overnight before removing corroded looking fasteners and that works about 10% of the time IME. Rest of the time I wind up using the reverse drill when it's a screw or bolt head, or using a cut off wheel when it's a nut. Careful what you do around the top cap because it can melt the rubber diaphragm if you get too aggressive.

[Agebot]

I don't have reverse drill bits, but I figure the easy outs serve the same purpose. I was using JIS bits as well. No idea what caused them to bind so much, but once I'd drilled the heads off of the screws and pulled the covers/floats off I could easily turn the shafts by hand. Instead of switching to socket head screws I replaced them with screws stainless steel screws that explicitly have the JIS dot on them, and a split washer.

That's for the carbs anyway.

My valve cover gasket was apparently sent to the wrong address and sent back, so still waiting, but I have a feeling I'm going the tear the breather gasket judging by the state of corrosion.

[The Buddha]

We replace those JIS crap wit allen stainless bolts (which is easy for me to say, I bought a few 1000 years ago to pack in with my jet kit).
Cool.
Buddha.