Ragh! Adjust Pilot Fuel Screw when on the bike (VM22SS / '79 550)

[roeme]

Alright, time for an update.

I have since taken off/put back on the carbs one more time, replacing the clamps with some nice stainless worm-gear type ones from the local craftsman (? not sure if translated correctly) store.
Reason the carbs came off one more was as mentioned earlier, #3 carb's bowl gasket shrunk and scraped the floats like #4 earlier, resulting in intermittent overflow.

Still, I seem to have a vacuum leak somewhere: When hot, the RPM's like to stay high. I was able to reproduce the issue reliably by SLOWLY turning the throttle a bit from idle - bike went up to 3K on its own.

Giving the throttle a quick blip, i.e. twitching once (and I mean really twitch, like supercharged parkinson), the RPM's fall down to idle with a reasonable speed (not slow as one would expect under vacuum leak condition).

Inlet boots seem ok, I couldn't see a tear from a cursory glance, and I had replaced the O-Rings earlier.

But given the gasket scraping floats, I'm not sure how much I can trust my earlier float measurement. Could a level too low cause the mixture to go lean? (Remember, VM22SS)

Next I will try the starter fluid spraying, still trying to figure out how to do that without setting my bike on fire. Can't really get the can close to the inlet boots, might need attach a hose or something.
Also have to jury-rig some auxiliary tank thingy.

The hunt is still on...

[chuck hahn]

Maybe a cable is dry or the grip itself is hanging up inside the switch housing. The grip also should get a little swipe of LIGHT grease as well.

[roeme]

Intermediate question: Could an airleak on the airbox side of the carbs cause a lean condition as well? I haven't yet bothered to check there as thoroughly as the inlet boots, reasoning that a leak there surely couldn't cause a much havoc as on the inlet boot side of the carbs.

Finally have the time to do the leak tests tomorrow.

[Nessism]

Air leaks on the back side of the carbs will mess up the mixture. My old 1000 wouldn't run for crap with the back side of the air box disconnected.

[roeme]

Update:
I have just checked there, and sure enough, #2 and #4 are leaky on the air box side. Could confirm with spray fluid. Reseated and tightened them up as much as I could - the clamps have definitively stretched.

Intake boots are fine and have hefty new clamps.

Going to put new clamps on the air box side as well.

[roeme]

Alright, finally some time for a proper update post. Pictures are clickable for full-size

TL;DR: At this point it's fair to say that my airbox boots #2 and #3 are shot.

I have put on new clamps, but the issue did persist.

Here's a shot of #4 carb after buttoning up. I forgot to take a picture of the other ones, unfortunately.


As one can see, the clamps are screw-style stainless steel ones, and they're a bit wider than stock. By using a hex screw, they allow for serious tension. So I tightened them up really good. Still, no dice

For fear of completely breaking either the carb inlet/outlet this way or the the boots, I didn't tighten as much as my hands would allow. Didn't want to leave the bike in the workshop for numerous weeks until replacement parts arrive, and the current state of affairs allows for short jaunts in my region. And my current gear won't allow me to ride in these conditions (-2°C / 29°F) for more than twenty minutes anyway.

Here's a vid of the issue for the interested reader, highlighting what I tried to put into text earlier on:

Unfortunately, I forgot to take a video how the RPM's change when spraying starter fluid on the airbox boots #2 / #3.

Also, when I was referring to the "throttle shaft seal", I meant this:


(It probably has a different name. But the parts schematics are just that tiny bit too far away right now ).

Just for posterity some additional pictures of the process:

Jury-rigged external fuel tank:


New clamps on the intake boots before putting the carbs back on (picture taken a few days ago, and not at the same place)



Now on to order replacement parts.

[chuck hahn]

The end caps are basically dust covers. As are the top cover gaskets. Nothing to worry about there.

[roeme]

After I've found the reason for, and solved the hanging idle over in this other thread, I was again confronted with a high idle.

This time however the reason was rather embarrassing; it was my jury-rigged vacuum line plug that failed.

Plugged properly, synced, and I'm now a happy camper.

[Efordman]

I messed up the original intake boots with clamps like those... They tend to want to pull the rubber away from the inner metal that's bolted to the head... New ones can be found and any vacuum leak no matter how small will make the bike act up ...I would suggest finding new clamps to replace the wide ones but that's only my opinion

[roeme]

I messed up the original intake boots with clamps like those... They tend to want to pull the rubber away from the inner metal that's bolted to the head... New ones can be found and any vacuum leak no matter how small will make the bike act up ...I would suggest finding new clamps to replace the wide ones but that's only my opinion

It's working fine for a few hundred kms now. The clamps sit snugly around the carb outlets, and do not exert any clamping force on the rubber part between head and carbs. Furthermore, there is a slight push from the airbox towards the head, so there should be no pulling forces on the vulcanized parts.

I've been told the rubber is vulcanized on the metal part, I can't quite imagine how those clamps could pull it off, other than ripping through wrong positioning.