Long road trip, how to prepare.

So in removing my carb to air box boots, I see that the bottom lip on the carb side has been working its way off. It's by no means loose, but it could be causing an air leak.

When I install the carbs, that bottom lip is always at an angle, and I have to really push it against the carbs as I tighten down the clamp. Is this a common experience?

Meanwhile, the clamp fastening screws on the carb to air box boots are bottoming out before they feel really tight. I may try using "normal" plumbing type hose clamps, even though I don't really like them. They seem not to put even pressure all the way 'round.

Do the carb to intake boots differ at all, or are they all the same? I may have gotten them mixed up, if so.

 

No, but they shrink after 32 years and no amount of boiling will make them the right size again.

When they get that shrunk (so much that they won't stay clamped any more) the only real solution is to replace them. Fortunately they're not horribly expensive. Check with Len.

 

I threw 'me in some boiling water and it seemed to help a lot. Before they had all sorts of bends and angles on the mating surface. Now they're almost all the same shape. Installed them with stainless plumbing clamps, and got creative with a dremel and washers to move the airbox assembly a bit closer and down a bit.

They fit a bit easier, and are now vertical. Hopefully the new clamps bite a bit more where it counts, even if it's just a temporary fix.

I removed the washers, and reassembled everything after blowing out all of the passages I could access with a few jets of carb cleaner.

One thing...The needles don't sit flat because of the little nub in the bottom of the diaphragm. This is normal right?

Waiting on the valve cover paint to dry, then I'm going to see how it runs.

 

Got it running again.

Compression test results warm:
#1: 150
#2:145
#3: 150
#4:150

Vacuum synced at 4K rpm
Color tuned to the "green" color right after blue, and took it about a hair past that. I'd rather be a bit rich after this whole experience.

Re-vacuum synced and colortuned one more round to the same spot.

It runs and idles well, but only a plug chop will tell if I'm still lean on the highway.

I'm going to ride to get some new plugs, They get a little overworked through the process.

One thing- #1 cylinder which has consistently given me the most problems idles with vacuum way less than the other three. It's only at the higher Roma that it levels out. Is this normal? The idle mixture screw is also about 4.5 turns out(fine thread).

I think I'll end up replacing the whole thing to see if it evens out with the others.

Got some shimming washers which should come on Tuesday, so if the plug chop still reads lean, I'm going to try throwing in a .008" shim.

Hopefully it doesn't turn into a mess like it did last time...

Thanks for all the help, everybody!

 

And some pics, because everyone like those...

Hand guards, not very pretty, but very effective at keeping you're hands toasty.


Tool and gas tubes


All hooked up

 

Also, anybody ever use a 90/100-19 front tire? I'm looking into one and they don't have 100/90-19's. If I recall correctly it's actually closer to spec...

 

All of my bikes call for 90/90/19 tires and I have 100-90-19's on every single one of them - my two XJ650's, XJ550, Virago 1100, and Virago 700. There is no problem with these tires, so feel free to use what fits!

 

Yeah, I suppose if the 90/90 fits, the 90/100 has to...just a taller tire.

Thanks!

 

Should be done at around 1050 RPM not 4K!

 

I've seen opinions both ways. If I'm going to be running at 4K for like 3 hours, I want it to be pulling equal vacuum at that rpm.

I could be wrong, so I'm up for suggestions.

When I sync at 1050, it never stays equal through the rev range.

 

It's not a matter of "opinion" Yamaha built the bikes and they said vac sync at 1050~1100rpm and then adjust the idle back to 1050. That's for idle. Once the butterflies are beyond about half open, that sync is no longer having an effect on anything.

Four grand is not quite in the "happy" range; you're going to be on trailing throttle a lot and the slides won't be fully open enough to get up onto the mains alone.

To be able to "trickle" along at low RPM and cruise at lower RPM (anything below 6K) not only does your vacuum sync (at 1050) need to be spot on, your float levels had better be uber-precise and your pilot mixtures dialed in, because they're going to still be called upon.

If you vac sync at 4K it ain't gonna idle for squat.

 

Thanks for chipping in, Fitz.

It's idling okay, but it still takes 2-3 blips of the starter to catch. Might be the reason.

This is a non-yics engine...would that make any difference?

The fluid displaced at the two rpm ranges is significantly different. Like cylinder pulls way harder at 4K, so when it returns to idle, it ends up well below the others.

I'll give it a try and see how she does. Waiting on shocks anyway so I might as well be tuning....